diff --git a/.github/workflows/compatibility_test-windows.yml b/.github/workflows/compatibility_test-windows.yml
index bc6b1ef81..04445be08 100644
--- a/.github/workflows/compatibility_test-windows.yml
+++ b/.github/workflows/compatibility_test-windows.yml
@@ -6,7 +6,7 @@ jobs:
   build:
     strategy:
       matrix:
-        go-version: [1.18.x, 1.21.x, 1.25.x]
+        go-version: [1.18.x, 1.21.x, 1.25.x, '1.27.0-rc.1']
     runs-on: windows-latest
     steps:
       - uses: actions/checkout@v2
diff --git a/.github/workflows/compatibility_test.yml b/.github/workflows/compatibility_test.yml
index da19b7e05..1242886df 100644
--- a/.github/workflows/compatibility_test.yml
+++ b/.github/workflows/compatibility_test.yml
@@ -6,8 +6,8 @@ jobs:
   build:
     strategy:
       matrix:
-        go-version: [1.18.x, 1.19.x, 1.20.x, 1.21.x, 1.22.x, 1.23.x, 1.24.x, 1.25.x]
-        os: [ubuntu-latest, ubuntu-24.04-arm, macos-latest]
+        go-version: [1.18.x, 1.19.x, 1.20.x, 1.21.x, 1.22.x, 1.23.x, 1.24.x, 1.25.x, '1.27.0-rc.1']
+        os: [ubuntu-latest, ubuntu-24.04-arm, macos-15]
     runs-on: ${{ matrix.os }}
     steps:
       - name: Clear repository
diff --git a/.github/workflows/test-arm64.yml b/.github/workflows/test-arm64.yml
index 254f9e9b1..24cd0836f 100644
--- a/.github/workflows/test-arm64.yml
+++ b/.github/workflows/test-arm64.yml
@@ -11,7 +11,7 @@ jobs:
 
     strategy:
       matrix:
-        go-version: [1.20.x, 1.22.x, 1.25.x]
+        go-version: [1.20.x, 1.22.x, 1.25.x, '1.27.0-rc.1']
         runner_arch: [ubuntu-24.04-arm, macos-latest]
 
     runs-on: ${{ matrix.runner_arch }}
diff --git a/.github/workflows/test-x86.yml b/.github/workflows/test-x86.yml
index 7835bfd3b..b320ab5ca 100644
--- a/.github/workflows/test-x86.yml
+++ b/.github/workflows/test-x86.yml
@@ -11,7 +11,7 @@ jobs:
 
     strategy:
       matrix:
-        go-version: [1.18.x, 1.21.x, 1.25.x]
+        go-version: [1.18.x, 1.21.x, 1.25.x, '1.27.0-rc.1']
         runner_arch: [ubuntu-latest]
 
     runs-on: ${{ matrix.runner_arch }}
diff --git a/README.md b/README.md
index 56b6f5cfd..8ded7ca65 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ A blazingly fast JSON serializing & deserializing library, accelerated by JI
 
 ## Requirement
 
-- Go: 1.18~1.26
+- Go: 1.18~1.27
   - Notice: Go1.24.0 is not supported due to the [issue](https://github.com/golang/go/issues/71672); please use a higher Go version or pass the build flag `-ldflags="-checklinkname=0"`.
 - OS: Linux / MacOS / Windows
 - CPU: AMD64 / (ARM64, need go1.20 above)
diff --git a/README_ZH_CN.md b/README_ZH_CN.md
index 0fa1c7042..8ffbefd03 100644
--- a/README_ZH_CN.md
+++ b/README_ZH_CN.md
@@ -6,7 +6,7 @@
 
 ## 依赖
 
-- Go: 1.18~1.26
+- Go: 1.18~1.27
   - 注意：Go1.24.0 由于 [issue](https://github.com/golang/go/issues/71672) 不可用，请升级到更高 Go 版本，或添加编译选项 `--ldflags="-checklinkname=0"` 
 - OS: Linux / MacOS / Windows
 - CPU: AMD64 / (ARM64, 需要 Go1.20 以上）
diff --git a/ast/api.go b/ast/api.go
index e28815114..4d6de961b 100644
--- a/ast/api.go
+++ b/ast/api.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2022 ByteDance Inc.
diff --git a/ast/api_compat.go b/ast/api_compat.go
index e88591bd0..834c7d215 100644
--- a/ast/api_compat.go
+++ b/ast/api_compat.go
@@ -1,5 +1,5 @@
-//go:build (!amd64 && !arm64) || go1.27 || !go1.17 || (arm64 && !go1.20)
-// +build !amd64,!arm64 go1.27 !go1.17 arm64,!go1.20
+//go:build (!amd64 && !arm64) || go1.28 || !go1.17 || (arm64 && !go1.20)
+// +build !amd64,!arm64 go1.28 !go1.17 arm64,!go1.20
 
 /*
 * Copyright 2022 ByteDance Inc.
diff --git a/ast/api_native_test.go b/ast/api_native_test.go
index 193d7d0bc..c742396c0 100644
--- a/ast/api_native_test.go
+++ b/ast/api_native_test.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2022 ByteDance Inc.
diff --git a/compat.go b/compat.go
index dcf9ef4ea..83cc6c210 100644
--- a/compat.go
+++ b/compat.go
@@ -1,5 +1,5 @@
-//go:build (!amd64 && !arm64) || go1.27 || !go1.17 || (arm64 && !go1.20)
-// +build !amd64,!arm64 go1.27 !go1.17 arm64,!go1.20
+//go:build (!amd64 && !arm64) || go1.28 || !go1.17 || (arm64 && !go1.20)
+// +build !amd64,!arm64 go1.28 !go1.17 arm64,!go1.20
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/decode_test.go b/decode_test.go
index 08a1d6f99..d00fc2fd7 100644
--- a/decode_test.go
+++ b/decode_test.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/decoder/decoder_compat.go b/decoder/decoder_compat.go
index 12a7cede4..98b5ce620 100644
--- a/decoder/decoder_compat.go
+++ b/decoder/decoder_compat.go
@@ -1,5 +1,5 @@
-//go:build (!amd64 && !arm64) || go1.27 || !go1.17 || (arm64 && !go1.20)
-// +build !amd64,!arm64 go1.27 !go1.17 arm64,!go1.20
+//go:build (!amd64 && !arm64) || go1.28 || !go1.17 || (arm64 && !go1.20)
+// +build !amd64,!arm64 go1.28 !go1.17 arm64,!go1.20
 
 /*
 * Copyright 2023 ByteDance Inc.
diff --git a/decoder/decoder_native.go b/decoder/decoder_native.go
index 8b51623b6..d8010f9ad 100644
--- a/decoder/decoder_native.go
+++ b/decoder/decoder_native.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
 * Copyright 2023 ByteDance Inc.
diff --git a/decoder/decoder_native_test.go b/decoder/decoder_native_test.go
index 07ffb0cee..58a9177d1 100644
--- a/decoder/decoder_native_test.go
+++ b/decoder/decoder_native_test.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/docs/json-v2-alignment.md b/docs/json-v2-alignment.md
new file mode 100644
index 000000000..87cab4fb8
--- /dev/null
+++ b/docs/json-v2-alignment.md
@@ -0,0 +1,80 @@
+# Sonic and `encoding/json` v2 (Go 1.27+)
+
+## Background
+
+Starting with **Go 1.27**, the standard library `encoding/json` v1 package is
+implemented on top of the new **json v2** implementation (`encoding/json/v2` +
+`encoding/json/jsontext`) with v1 compatibility options. The v1 API remains
+supported, but some edge cases still produce different errors or values when the
+json v2 backend is active. Builds can temporarily opt out with
+`GOEXPERIMENT=nojsonv2` (this opt-out is expected to be removed in a future Go
+release).
+
+Sonic is a drop-in replacement for `encoding/json` and currently implements
+**v1 semantics**. On Go 1.27 with the default json v2 backend, a small set of
+legacy parity tests still diverge between `sonic` and the standard library. This
+document tracks those divergences.
+
+> Sonic still **builds and runs correctly** on Go 1.27 (native JIT path). These
+> are *semantic* differences against the new std reference, not crashes or
+> miscompilations in sonic.
+
+## How tests handle this
+
+`issue_test` contains cases that assert byte-for-byte parity or exact error/value
+parity against the *live* `encoding/json`. Those cases are gated on a
+build-tag-derived constant:
+
+- `issue_test/jsonv2_compat_test.go` (`//go:build goexperiment.jsonv2`) → `stdUsesJSONV2 = true`
+- `issue_test/jsonv1_compat_test.go` (`//go:build !goexperiment.jsonv2`) → `stdUsesJSONV2 = false`
+
+The `goexperiment.jsonv2` tag is set automatically when the json v2 backend is
+active (default on Go 1.27+, unset under `GOEXPERIMENT=nojsonv2` and on Go ≤1.26).
+Tests keep Sonic-only assertions where they have stable expected values and skip
+only the std parity check or whole parity-only test when `stdUsesJSONV2` is true,
+so:
+
+- Go ≤ 1.26, or Go 1.27 with `GOEXPERIMENT=nojsonv2`: full parity coverage runs.
+- Go 1.27 default (v2): the divergent std parity assertions are skipped.
+
+## Known divergences (surfaced by issue_test)
+
+| Test | Area | sonic / legacy behavior | Go 1.27 std jsonv2-backend behavior |
+|------|------|---------------------|---------------------------|
+| Issue460 | number → float32/float64 overflow | returns error, leaves dest at 0 | saturates dest to `±Inf` (still returns error) |
+| Issue491 | marshal/unmarshal unsupported types | `map[*T]*T`, `[]chan T`, etc. error as unsupported | some pointer-keyed maps now marshal successfully; unsupported unmarshal error handling differs |
+| Issue747 | map key float32/float64 | v1 parsing | v2 number/key parsing differs |
+| Issue144 | `,string` option on pointer/number fields | v1 string-option semantics | v2 string-option semantics |
+| Issue379 | unmarshal into `MyPtr`/`**T` with Unmarshaler | v1 pointer-allocation/Unmarshaler dispatch | v2 dispatch differs |
+| Issue670 | custom `UnmarshalJSON` error cases | v1 error/typing | v2 error/typing |
+| Issue758 | self-referential `interface{}` (`v = &v`) | sonic handles it | **v2 std recurses to stack overflow** (sonic is fine) |
+| Issue772 | skipping iface-typed fields (non-ptr / nil) | v1 skip behavior | v2 skip behavior differs |
+| Issue824 (`TestFloatMap`) | marshal `map[float64]string` | **errors** (`json: unsupported type: map[float64]string`) | **marshals successfully** (`{"1":""}`) |
+| Issue827 | `TextMarshaler` types (e.g. `string3`) | v1 TextMarshaler handling | v2 TextMarshaler handling differs |
+
+Additional documented json v2 behavior changes are likely to affect parity if
+Sonic later chooses to expose a v2-compatible mode (not all currently covered by
+a dedicated test):
+
+- **Stricter UTF-8**: invalid UTF-8 bytes in JSON strings are rejected.
+- **Duplicate object keys**: objects with duplicate member names are rejected.
+- Error message text differs (sonic already differs here, generally tolerated).
+
+## Decision / status
+
+- **Supporting Go 1.27 (build + run): done.** Native path validated; full test
+  suite green under `GOEXPERIMENT=nojsonv2` and with the v2 parity gates above.
+- **Aligning Sonic to json v2 behavior: not started — separate workstream.**
+  This is a larger design question (whether/when Sonic offers a v2-compatible
+  API). Track here as the list of behaviors to reconcile if/when that work is
+  scheduled.
+
+## Reproducing locally
+
+```sh
+# v2 default (skips parity tests)
+env -u GOROOT GOTOOLCHAIN=local /path/to/go1.27/bin/go test ./issue_test/...
+
+# force v1 semantics (full parity coverage)
+env -u GOROOT GOEXPERIMENT=nojsonv2 GOTOOLCHAIN=local /path/to/go1.27/bin/go test ./issue_test/...
+```
diff --git a/encode_test.go b/encode_test.go
index fb39c68e9..8a4ff4da8 100644
--- a/encode_test.go
+++ b/encode_test.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/encoder/encoder_compat.go b/encoder/encoder_compat.go
index ae4a76e54..3fd8468d1 100644
--- a/encoder/encoder_compat.go
+++ b/encoder/encoder_compat.go
@@ -1,5 +1,5 @@
-//go:build (!amd64 && !arm64) || go1.27 || !go1.17 || (arm64 && !go1.20)
-// +build !amd64,!arm64 go1.27 !go1.17 arm64,!go1.20
+//go:build (!amd64 && !arm64) || go1.28 || !go1.17 || (arm64 && !go1.20)
+// +build !amd64,!arm64 go1.28 !go1.17 arm64,!go1.20
 
 /*
 * Copyright 2023 ByteDance Inc.
diff --git a/encoder/encoder_native.go b/encoder/encoder_native.go
index d62fb37d4..acbfaaf49 100644
--- a/encoder/encoder_native.go
+++ b/encoder/encoder_native.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2023 ByteDance Inc.
diff --git a/encoder/encoder_native_test.go b/encoder/encoder_native_test.go
index c891a2cca..63d4218c0 100644
--- a/encoder/encoder_native_test.go
+++ b/encoder/encoder_native_test.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/internal/compat/warn.go b/internal/compat/warn.go
index 7b2ecb0b9..67c023a34 100644
--- a/internal/compat/warn.go
+++ b/internal/compat/warn.go
@@ -1,12 +1,13 @@
-// +build !amd64,!arm64 go1.27 !go1.17 arm64,!go1.20
+//go:build (!amd64 && !arm64) || go1.28 || !go1.17 || (arm64 && !go1.20)
+// +build !amd64,!arm64 go1.28 !go1.17 arm64,!go1.20
 
 package compat
 
 import (
-    "fmt"
-    "os"
+	"fmt"
+	"os"
 )
 
 func Warn(prefix string) {
-    fmt.Fprintf(os.Stderr, "WARNING: %s only supports (go1.17~1.26 and amd64 CPU) or (go1.20~1.26 and arm64 CPU), but your environment is not suitable and will fallback to encoding/json\n", prefix)
+	fmt.Fprintf(os.Stderr, "WARNING: %s only supports (go1.17~1.27 and amd64 CPU) or (go1.20~1.27 and arm64 CPU), but your environment is not suitable and will fallback to encoding/json\n", prefix)
 }
diff --git a/internal/decoder/api/decoder_amd64.go b/internal/decoder/api/decoder_amd64.go
index aea6bfc46..b5161a121 100644
--- a/internal/decoder/api/decoder_amd64.go
+++ b/internal/decoder/api/decoder_amd64.go
@@ -1,5 +1,5 @@
-//go:build go1.17 && !go1.27
-// +build go1.17,!go1.27
+//go:build go1.17 && !go1.28
+// +build go1.17,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/internal/decoder/api/decoder_arm64.go b/internal/decoder/api/decoder_arm64.go
index 42f6d68d8..b1e751005 100644
--- a/internal/decoder/api/decoder_arm64.go
+++ b/internal/decoder/api/decoder_arm64.go
@@ -1,5 +1,5 @@
-//go:build go1.17 && !go1.27
-// +build go1.17,!go1.27
+//go:build go1.17 && !go1.28
+// +build go1.17,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/internal/decoder/jitdec/asm_stubs_amd64_go121.go b/internal/decoder/jitdec/asm_stubs_amd64_go121.go
index 7908c1d6d..38a04b53f 100644
--- a/internal/decoder/jitdec/asm_stubs_amd64_go121.go
+++ b/internal/decoder/jitdec/asm_stubs_amd64_go121.go
@@ -1,5 +1,5 @@
-//go:build go1.21 && !go1.27
-// +build go1.21,!go1.27
+//go:build go1.21 && !go1.28
+// +build go1.21,!go1.28
 
 // Copyright 2023 CloudWeGo Authors
 //
diff --git a/internal/decoder/jitdec/assembler_regabi_amd64.go b/internal/decoder/jitdec/assembler_regabi_amd64.go
index 366e8beb4..4c6bdcfb3 100644
--- a/internal/decoder/jitdec/assembler_regabi_amd64.go
+++ b/internal/decoder/jitdec/assembler_regabi_amd64.go
@@ -1,5 +1,5 @@
-//go:build go1.17 && !go1.27
-// +build go1.17,!go1.27
+//go:build go1.17 && !go1.28
+// +build go1.17,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/internal/decoder/jitdec/generic_regabi_amd64.go b/internal/decoder/jitdec/generic_regabi_amd64.go
index 7ddf631d6..1ebc8afbe 100644
--- a/internal/decoder/jitdec/generic_regabi_amd64.go
+++ b/internal/decoder/jitdec/generic_regabi_amd64.go
@@ -1,5 +1,5 @@
-//go:build go1.17 && !go1.27
-// +build go1.17,!go1.27
+//go:build go1.17 && !go1.28
+// +build go1.17,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/internal/encoder/alg/spec.go b/internal/encoder/alg/spec.go
index 3a3241c11..f58ca0ca4 100644
--- a/internal/encoder/alg/spec.go
+++ b/internal/encoder/alg/spec.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.16 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.16,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.16 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.16,!go1.28 arm64,go1.20,!go1.28
 
 /**
  * Copyright 2024 ByteDance Inc.
diff --git a/internal/encoder/alg/spec_compat.go b/internal/encoder/alg/spec_compat.go
index b25308228..9f2bbf51a 100644
--- a/internal/encoder/alg/spec_compat.go
+++ b/internal/encoder/alg/spec_compat.go
@@ -1,5 +1,5 @@
-//go:build (!amd64 && !arm64) || go1.27 || !go1.16 || (arm64 && !go1.20)
-// +build !amd64,!arm64 go1.27 !go1.16 arm64,!go1.20
+//go:build (!amd64 && !arm64) || go1.28 || !go1.16 || (arm64 && !go1.20)
+// +build !amd64,!arm64 go1.28 !go1.16 arm64,!go1.20
 
 /**
  * Copyright 2024 ByteDance Inc.
diff --git a/internal/encoder/x86/asm_stubs_amd64_go121.go b/internal/encoder/x86/asm_stubs_amd64_go121.go
index 818e98307..4748a6385 100644
--- a/internal/encoder/x86/asm_stubs_amd64_go121.go
+++ b/internal/encoder/x86/asm_stubs_amd64_go121.go
@@ -1,5 +1,5 @@
-//go:build go1.21 && !go1.27
-// +build go1.21,!go1.27
+//go:build go1.21 && !go1.28
+// +build go1.21,!go1.28
 
 // Copyright 2023 CloudWeGo Authors
 //
diff --git a/internal/encoder/x86/assembler_export_amd64.go b/internal/encoder/x86/assembler_export_amd64.go
index 6df604286..69d81f3de 100644
--- a/internal/encoder/x86/assembler_export_amd64.go
+++ b/internal/encoder/x86/assembler_export_amd64.go
@@ -1,5 +1,5 @@
-//go:build go1.17 && !go1.27
-// +build go1.17,!go1.27
+//go:build go1.17 && !go1.28
+// +build go1.17,!go1.28
 
 package x86
 
diff --git a/internal/encoder/x86/assembler_regabi_amd64.go b/internal/encoder/x86/assembler_regabi_amd64.go
index a62579b7c..b1c84eb10 100644
--- a/internal/encoder/x86/assembler_regabi_amd64.go
+++ b/internal/encoder/x86/assembler_regabi_amd64.go
@@ -1,5 +1,5 @@
-//go:build go1.17 && !go1.27
-// +build go1.17,!go1.27
+//go:build go1.17 && !go1.28
+// +build go1.17,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/internal/encoder/x86/debug_go117.go b/internal/encoder/x86/debug_go117.go
index 79a86f423..aa4a599bf 100644
--- a/internal/encoder/x86/debug_go117.go
+++ b/internal/encoder/x86/debug_go117.go
@@ -1,5 +1,5 @@
-//go:build go1.17 && !go1.27
-// +build go1.17,!go1.27
+//go:build go1.17 && !go1.28
+// +build go1.17,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/internal/rt/base64_amd64.go b/internal/rt/base64_amd64.go
index f2f1ad8fb..59ab11ce8 100644
--- a/internal/rt/base64_amd64.go
+++ b/internal/rt/base64_amd64.go
@@ -1,5 +1,5 @@
-//go:build amd64 && go1.17 && !go1.27
-// +build amd64,go1.17,!go1.27
+//go:build amd64 && go1.17 && !go1.28
+// +build amd64,go1.17,!go1.28
 
 package rt
 
diff --git a/internal/rt/base64_compat.go b/internal/rt/base64_compat.go
index 88e28ca3a..4e23722da 100644
--- a/internal/rt/base64_compat.go
+++ b/internal/rt/base64_compat.go
@@ -1,5 +1,5 @@
-//go:build !amd64 || !go1.17 || go1.27
-// +build !amd64 !go1.17 go1.27
+//go:build !amd64 || !go1.17 || go1.28
+// +build !amd64 !go1.17 go1.28
 
 package rt
 
diff --git a/internal/rt/gcwb.go b/internal/rt/gcwb.go
index fb7e1cc37..eafef90a0 100644
--- a/internal/rt/gcwb.go
+++ b/internal/rt/gcwb.go
@@ -1,5 +1,5 @@
-//go:build go1.21 && !go1.27
-// +build go1.21,!go1.27
+//go:build go1.21 && !go1.28
+// +build go1.21,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/internal/rt/map.go b/internal/rt/map.go
index 61a99dfec..7f2c6cba6 100644
--- a/internal/rt/map.go
+++ b/internal/rt/map.go
@@ -22,4 +22,6 @@ type GoMapIterator struct {
 	I           uint8
 	Bucket      uintptr
 	CheckBucket uintptr
+	// different from go1.23, noswissmap
+	ClearSeq uint64
 }
diff --git a/issue_test/issue144_test.go b/issue_test/issue144_test.go
index 398ba8e33..8c7b67608 100644
--- a/issue_test/issue144_test.go
+++ b/issue_test/issue144_test.go
@@ -12,33 +12,36 @@
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
-*/
+ */
 
 package issue_test
 
 import (
-    `encoding/json`
-    `testing`
+	"encoding/json"
+	"testing"
 
-    `github.com/stretchr/testify/require`
-    `github.com/davecgh/go-spew/spew`
-    `github.com/bytedance/sonic`
+	"github.com/bytedance/sonic"
+	"github.com/davecgh/go-spew/spew"
+	"github.com/stretchr/testify/require"
 )
 
 type Issue144_StringOption struct {
-    S1 *string      `json:"s1,string"`
-    S2 *string      `json:"s2,string"`
-    S3 string       `json:"s3,string"`
-    J1 json.Number  `json:"j1,string"`
-    J2 *json.Number `json:"j2,string"`
-    J3 *json.Number `json:"j3,string"`
-    I1 int          `json:"i1,string"`
-    I2 *int         `json:"i2,string"`
-    I3 *int         `json:"i3,string"`
+	S1 *string      `json:"s1,string"`
+	S2 *string      `json:"s2,string"`
+	S3 string       `json:"s3,string"`
+	J1 json.Number  `json:"j1,string"`
+	J2 *json.Number `json:"j2,string"`
+	J3 *json.Number `json:"j3,string"`
+	I1 int          `json:"i1,string"`
+	I2 *int         `json:"i2,string"`
+	I3 *int         `json:"i3,string"`
 }
 
 func TestIssue144_StringOption(t *testing.T) {
-    data := []byte(`{
+	if stdUsesJSONV2 {
+		t.Skip("std encoding/json jsonv2 backend differs for this legacy parity case; see docs/json-v2-alignment.md")
+	}
+	data := []byte(`{
         "s1":"\"null\"",
         "s2":"null",
         "s3":"null",
@@ -50,23 +53,23 @@ func TestIssue144_StringOption(t *testing.T) {
         "i3":"-123"
     }`)
 
-    var v1, v2 Issue144_StringOption
-    e1 := json.Unmarshal(data, &v1)
-    e2 := sonic.Unmarshal(data, &v2)
-    require.NoError(t, e1)
-    require.NoError(t, e2)
-    require.Equal(t, v1, v2)
-    spew.Dump(v1)
+	var v1, v2 Issue144_StringOption
+	e1 := json.Unmarshal(data, &v1)
+	e2 := sonic.Unmarshal(data, &v2)
+	require.NoError(t, e1)
+	require.NoError(t, e2)
+	require.Equal(t, v1, v2)
+	spew.Dump(v1)
 
-    i, j, s := int(1), json.Number("1"), "null"
-    v1.I2, v2.I2 = &i, &i
-    v1.J2, v2.J2 = &j, &j
-    v1.S2, v2.S2 = &s, &s
+	i, j, s := int(1), json.Number("1"), "null"
+	v1.I2, v2.I2 = &i, &i
+	v1.J2, v2.J2 = &j, &j
+	v1.S2, v2.S2 = &s, &s
 
-    e1 = json.Unmarshal(data, &v1)
-    e2 = sonic.Unmarshal(data, &v2)
-    require.NoError(t, e1)
-    require.NoError(t, e2)
-    require.Equal(t, v1, v2)
-    spew.Dump(v1)
-}
\ No newline at end of file
+	e1 = json.Unmarshal(data, &v1)
+	e2 = sonic.Unmarshal(data, &v2)
+	require.NoError(t, e1)
+	require.NoError(t, e2)
+	require.Equal(t, v1, v2)
+	spew.Dump(v1)
+}
diff --git a/issue_test/issue379_test.go b/issue_test/issue379_test.go
index 109e26cbc..5d2ab67bf 100644
--- a/issue_test/issue379_test.go
+++ b/issue_test/issue379_test.go
@@ -26,97 +26,100 @@ import (
 )
 
 type Foo struct {
-    Name string
+	Name string
 }
 
 func (f *Foo) UnmarshalJSON(data []byte) error {
-    println("UnmarshalJSON called!!!")
-    f.Name = "Unmarshaler"
-    return nil
+	println("UnmarshalJSON called!!!")
+	f.Name = "Unmarshaler"
+	return nil
 }
 
 type MyPtr *Foo
 
 func TestIssue379(t *testing.T) {
-    tests := []struct{
-        data  string
-        newf  func() interface{} 
-        equal func(exp, act interface{}) bool 
-    } {
-        {
-            data: `{"Name":"MyPtr"}`,
-            newf:  func() interface{} { return &Foo{} },
-        },
-        {
-            data: `{"Name":"MyPtr"}`,
-            newf:  func() interface{} { ptr := &Foo{}; return &ptr },
-        },
-        {
-            data: `{"Name":"MyPtr"}`,
-            newf:  func() interface{} { return MyPtr(&Foo{}) },
-        },
-        {
-            data: `{"Name":"MyPtr"}`,
-            newf:  func() interface{} { ptr := MyPtr(&Foo{}); return &ptr },
-        },
+	if stdUsesJSONV2 {
+		t.Skip("std encoding/json jsonv2 backend differs for this legacy parity case; see docs/json-v2-alignment.md")
+	}
+	tests := []struct {
+		data  string
+		newf  func() interface{}
+		equal func(exp, act interface{}) bool
+	}{
+		{
+			data: `{"Name":"MyPtr"}`,
+			newf: func() interface{} { return &Foo{} },
+		},
+		{
+			data: `{"Name":"MyPtr"}`,
+			newf: func() interface{} { ptr := &Foo{}; return &ptr },
+		},
+		{
+			data: `{"Name":"MyPtr"}`,
+			newf: func() interface{} { return MyPtr(&Foo{}) },
+		},
+		{
+			data: `{"Name":"MyPtr"}`,
+			newf: func() interface{} { ptr := MyPtr(&Foo{}); return &ptr },
+		},
 
-        // TODO: fix jit tests
-        // {
-        //     data: `null`,
-        //     newf:  func() interface{} { return MyPtr(&Foo{}) },
-        // },
-        // {
-        //     data: `null`,
-        //     newf:  func() interface{} { ptr := MyPtr(&Foo{}); return &ptr },
-        // },
-        // {
-        //     data: `null`,
-        //     newf:  func() interface{} { 
-        //         x :=  &Foo{Name: "mock"}
-        //         return x },
-        // },
-        // {
-        //     data: `null`,
-        //     newf:  func() interface{} { ptr := &Foo{}; return &ptr },
-        // },
-        {
-            data: `{"map":{"Name":"MyPtr"}}`,
-            newf:  func() interface{} { return new(map[string]MyPtr) },
-        },
-        {
-            data: `{"map":{"Name":"MyPtr"}}`,
-            newf:  func() interface{} { return new(map[string]*Foo) },
-        },
-        {
-            data: `{"map":{"Name":"MyPtr"}}`,
-            newf:  func() interface{} { return new(map[string]*MyPtr) },
-        },
-        {
-            data: `[{"Name":"MyPtr"}]`,
-            newf:  func() interface{} { return new([]MyPtr) },
-        },
-        {
-            data: `[{"Name":"MyPtr"}]`,
-            newf:  func() interface{} { return new([]*MyPtr) },
-        },
-        {
-            data: `[{"Name":"MyPtr"}]`,
-            newf:  func() interface{} { return new([]*Foo) },
-        },
-    }
+		// TODO: fix jit tests
+		// {
+		//     data: `null`,
+		//     newf:  func() interface{} { return MyPtr(&Foo{}) },
+		// },
+		// {
+		//     data: `null`,
+		//     newf:  func() interface{} { ptr := MyPtr(&Foo{}); return &ptr },
+		// },
+		// {
+		//     data: `null`,
+		//     newf:  func() interface{} {
+		//         x :=  &Foo{Name: "mock"}
+		//         return x },
+		// },
+		// {
+		//     data: `null`,
+		//     newf:  func() interface{} { ptr := &Foo{}; return &ptr },
+		// },
+		{
+			data: `{"map":{"Name":"MyPtr"}}`,
+			newf: func() interface{} { return new(map[string]MyPtr) },
+		},
+		{
+			data: `{"map":{"Name":"MyPtr"}}`,
+			newf: func() interface{} { return new(map[string]*Foo) },
+		},
+		{
+			data: `{"map":{"Name":"MyPtr"}}`,
+			newf: func() interface{} { return new(map[string]*MyPtr) },
+		},
+		{
+			data: `[{"Name":"MyPtr"}]`,
+			newf: func() interface{} { return new([]MyPtr) },
+		},
+		{
+			data: `[{"Name":"MyPtr"}]`,
+			newf: func() interface{} { return new([]*MyPtr) },
+		},
+		{
+			data: `[{"Name":"MyPtr"}]`,
+			newf: func() interface{} { return new([]*Foo) },
+		},
+	}
 
-    for i, tt := range tests {
-        println(i)
-        jv, sv := tt.newf(), tt.newf()
-        jerr := json.Unmarshal([]byte(tt.data), jv)
-        serr := sonic.Unmarshal([]byte(tt.data), sv)
-        require.Equal(t, jv, sv)
-        require.Equal(t, jerr, serr)
+	for i, tt := range tests {
+		println(i)
+		jv, sv := tt.newf(), tt.newf()
+		jerr := json.Unmarshal([]byte(tt.data), jv)
+		serr := sonic.Unmarshal([]byte(tt.data), sv)
+		require.Equal(t, jv, sv)
+		require.Equal(t, jerr, serr)
 
-        jv, sv = tt.newf(), tt.newf()
-        jerr = json.Unmarshal([]byte(tt.data), &jv)
-        serr = sonic.Unmarshal([]byte(tt.data), &sv)
-        require.Equal(t, jv, sv, spew.Sdump(jv, sv))
-        require.Equal(t, jerr, serr)
-    }
+		jv, sv = tt.newf(), tt.newf()
+		jerr = json.Unmarshal([]byte(tt.data), &jv)
+		serr = sonic.Unmarshal([]byte(tt.data), &sv)
+		require.Equal(t, jv, sv, spew.Sdump(jv, sv))
+		require.Equal(t, jerr, serr)
+	}
 }
diff --git a/issue_test/issue460_test.go b/issue_test/issue460_test.go
index d76a69d8d..dba23b3f4 100644
--- a/issue_test/issue460_test.go
+++ b/issue_test/issue460_test.go
@@ -12,54 +12,59 @@
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
-*/
+ */
 package issue_test
+
 import (
-    `encoding/json`
-    `testing`
-    `github.com/bytedance/sonic`
-    `github.com/stretchr/testify/require`
+	"encoding/json"
+	"testing"
+
+	"github.com/bytedance/sonic"
+	"github.com/stretchr/testify/require"
 )
 
 // TODO: fix float32
 func TestIssue460_UnmarshalMaxFloat32(t *testing.T) {
-    tests := []string {
-        // max.MaxFloat32
-        "3.40282346638528859811704183484516925440e+38",
+	if stdUsesJSONV2 {
+		t.Skip("std encoding/json jsonv2 backend differs for this legacy parity case; see docs/json-v2-alignment.md")
+	}
+	tests := []string{
+		// max.MaxFloat32
+		"3.40282346638528859811704183484516925440e+38",
 
-        // round up to max.MaxFloat32
-        // "3.402823469e+38",
-        "3.40282346e+38",
-        // "3.40282347e+38",
-        // "3.40282348e+38",
-        // "3.4028235e+38",
-        // TODO: fix this case
-        // "3.4028235677973366e+38",  // Bits: 1000111111011111111111111111111111_10000000000000000000000000000
+		// round up to max.MaxFloat32
+		// "3.402823469e+38",
+		"3.40282346e+38",
+		// "3.40282347e+38",
+		// "3.40282348e+38",
+		// "3.4028235e+38",
+		// TODO: fix this case
+		// "3.4028235677973366e+38",  // Bits: 1000111111011111111111111111111111_10000000000000000000000000000
 
-        // overflow for float32, round up to max.MaxFloat32 + 1
-        "3.402823567797337e+38", // Bits: 1000111111011111111111111111111111_10000000000000000000000000001
-        "3.402823567797338e+38",
-        // "3.4028236e+38",
-    }
+		// overflow for float32, round up to max.MaxFloat32 + 1
+		"3.402823567797337e+38", // Bits: 1000111111011111111111111111111111_10000000000000000000000000001
+		"3.402823567797338e+38",
+		// "3.4028236e+38",
+	}
 
-    t.Run("max float32", func(t *testing.T) {
-        for _, data := range(tests) {
-            var f1, f2  float32
-            se := sonic.UnmarshalString(data, &f1)
-            je := json.Unmarshal([]byte(data), &f2)
-            require.Equal(t, se != nil, je != nil, data, se, je)
-            require.Equal(t, f2, f1, data)
-        }
-    })
+	t.Run("max float32", func(t *testing.T) {
+		for _, data := range tests {
+			var f1, f2 float32
+			se := sonic.UnmarshalString(data, &f1)
+			je := json.Unmarshal([]byte(data), &f2)
+			require.Equal(t, se != nil, je != nil, data, se, je)
+			require.Equal(t, f2, f1, data)
+		}
+	})
 
-    t.Run("min float32", func(t *testing.T) {
-        for _, data := range(tests) {
-            data = string("-") + data
-            var f1, f2  float32
-            se := sonic.UnmarshalString(data, &f1)
-            je := json.Unmarshal([]byte(data), &f2)
-            require.Equal(t, se != nil, je != nil, data, se, je)
-            require.Equal(t, f2, f1, data)
-        }
-    })
+	t.Run("min float32", func(t *testing.T) {
+		for _, data := range tests {
+			data = string("-") + data
+			var f1, f2 float32
+			se := sonic.UnmarshalString(data, &f1)
+			je := json.Unmarshal([]byte(data), &f2)
+			require.Equal(t, se != nil, je != nil, data, se, je)
+			require.Equal(t, f2, f1, data)
+		}
+	})
 }
diff --git a/issue_test/issue491_test.go b/issue_test/issue491_test.go
index 3d1fb65ac..8d9ec2564 100644
--- a/issue_test/issue491_test.go
+++ b/issue_test/issue491_test.go
@@ -13,8 +13,8 @@ type Unsupported struct {
 }
 
 type StructWithUnsupported struct {
-	Foo *Unsupported	`json:"foo"`
-	Bar *Unsupported	`json:"bar,omitempty"`
+	Foo *Unsupported `json:"foo"`
+	Bar *Unsupported `json:"bar,omitempty"`
 }
 
 type Foo2 struct {
@@ -27,8 +27,11 @@ type MockContext struct {
 }
 
 func TestIssue491_MarshalUnsupportedType(t *testing.T) {
+	if stdUsesJSONV2 {
+		t.Skip("std encoding/json jsonv2 backend differs for this legacy parity case; see docs/json-v2-alignment.md")
+	}
 	// Wrapper a unbale serde type
-	tests := []interface{} {
+	tests := []interface{}{
 		map[string]*Function{},
 		map[*Function]*Function{},
 		map[string]Function{},
@@ -43,32 +46,36 @@ func TestIssue491_MarshalUnsupportedType(t *testing.T) {
 		chan int(nil),
 		new(MockContext),
 	}
-	for _, v := range(tests) {
+	for _, v := range tests {
 		assertMarshal(t, sonic.ConfigDefault, v)
 	}
 }
 
- func TestIssue491_UnmarshalUnsupported(t *testing.T) {
+func TestIssue491_UnmarshalUnsupported(t *testing.T) {
+	if stdUsesJSONV2 {
+		t.Skip("std encoding/json jsonv2 backend differs for this legacy parity case; see docs/json-v2-alignment.md")
+	}
+
 	type Test struct {
-		data string
+		data  string
 		value interface{}
 	}
 
 	tests := []unmTestCase{
 		{
-			name: "unsupported type slice",
-			data: []byte("null"),
-			newfn: func() interface{} { return new([]Function)},
+			name:  "unsupported type slice",
+			data:  []byte("null"),
+			newfn: func() interface{} { return new([]Function) },
 		},
-		{ 
-			name: "unsupported type",
-			data: []byte("[null, null]"),
+		{
+			name:  "unsupported type",
+			data:  []byte("[null, null]"),
 			newfn: func() interface{} { return new([]chan int) },
 		},
 		{
 			name: "unsupported type in struct",
 			data: []byte("{\"foo\": null}"),
-			newfn: func() interface{} {  
+			newfn: func() interface{} {
 				return new(struct {
 					Foo Function
 				})
@@ -77,13 +84,12 @@ func TestIssue491_MarshalUnsupportedType(t *testing.T) {
 		{
 			name: "unsupported type in map key should be error",
 			data: []byte("null"),
-			newfn: func() interface{} {  
+			newfn: func() interface{} {
 				return map[chan int]Function{}
 			},
 		},
 	}
-	for _, v := range(tests) {
+	for _, v := range tests {
 		assertUnmarshal(t, sonic.ConfigDefault, v)
 	}
- }
- 
\ No newline at end of file
+}
diff --git a/issue_test/issue670_test.go b/issue_test/issue670_test.go
index 15f554994..9e3d9fbd3 100644
--- a/issue_test/issue670_test.go
+++ b/issue_test/issue670_test.go
@@ -26,13 +26,16 @@ import (
 )
 
 func TestIssue670_JSONMarshaler(t *testing.T) {
-	var obj = Issue670JSONMarshaler{ D: Date(time.Now().Unix()) }
+	var obj = Issue670JSONMarshaler{D: Date(time.Now().Unix())}
 	so, _ := sonic.MarshalString(obj)
 	eo, _ := json.Marshal(obj)
 	assert.Equal(t, string(eo), so)
 }
 
 func TestIssue670_JSONUnmarshaler(t *testing.T) {
+	if stdUsesJSONV2 {
+		t.Skip("std encoding/json jsonv2 backend differs for this legacy parity case; see docs/json-v2-alignment.md")
+	}
 	// match
 	eo := []byte(`{"D":"2021-08-26","E":1}`)
 	et := reflect.TypeOf(Issue670JSONMarshaler{})
@@ -52,7 +55,7 @@ func testUnmarshal(t *testing.T, eo []byte, rt reflect.Type, checkobj bool) {
 	es := sonic.Unmarshal(eo, obj)
 	obj2 := reflect.New(rt).Interface()
 	ee := json.Unmarshal(eo, obj2)
-	assert.Equal(t, ee ==nil, es == nil, es)
+	assert.Equal(t, ee == nil, es == nil, es)
 	if checkobj {
 		assert.Equal(t, obj2, obj)
 	}
@@ -61,7 +64,7 @@ func testUnmarshal(t *testing.T, eo []byte, rt reflect.Type, checkobj bool) {
 }
 
 func TestIssue670_TextMarshaler(t *testing.T) {
-	var obj = Issue670TextMarshaler{ D: int(time.Now().Unix()) }
+	var obj = Issue670TextMarshaler{D: int(time.Now().Unix())}
 	so, _ := sonic.MarshalString(obj)
 	eo, _ := json.Marshal(obj)
 	assert.Equal(t, string(eo), so)
@@ -84,8 +87,8 @@ func TestIssue670_TextUnmarshaler(t *testing.T) {
 }
 
 type Issue670JSONMarshaler struct {
-	D      Date                 `form:"D" json:"D,string" query:"D"`
-	E      int
+	D Date `form:"D" json:"D,string" query:"D"`
+	E int
 }
 
 type Date int64
@@ -102,7 +105,7 @@ func (d *Date) UnmarshalJSON(in []byte) error {
 		*d = 0
 		return nil
 	}
-	
+
 	t, err := time.Parse("2006-01-02", string(in))
 	if err != nil {
 		return err
@@ -112,11 +115,10 @@ func (d *Date) UnmarshalJSON(in []byte) error {
 }
 
 type Issue670TextMarshaler struct {
-	D      int                 `form:"D" json:"D,string" query:"D"`
-	E      int
+	D int `form:"D" json:"D,string" query:"D"`
+	E int
 }
 
-
 type Date2 int64
 
 func (d Date2) MarshalText() ([]byte, error) {
@@ -137,4 +139,4 @@ func (d *Date2) UnmarshalText(in []byte) error {
 	}
 	*d = Date2(t.Unix())
 	return nil
-}
\ No newline at end of file
+}
diff --git a/issue_test/issue747_test.go b/issue_test/issue747_test.go
index 9f45a5d2f..62111bdca 100644
--- a/issue_test/issue747_test.go
+++ b/issue_test/issue747_test.go
@@ -24,24 +24,24 @@ import (
 
 func TestIssue747(t *testing.T) {
 	tests := []struct {
-		name           string
-		input         string
+		name     string
+		input    string
 		expected interface{}
-		newfn func() interface{}
+		newfn    func() interface{}
 	}{
 		{
-			name:   "unmarshal map key float64",
+			name:  "unmarshal map key float64",
 			input: `{"1.2":1.8}`,
 			expected: &map[float64]float64{
-				1.2:  1.8,
+				1.2: 1.8,
 			},
 			newfn: func() interface{} { return new(map[float64]float64) },
 		},
 		{
-			name:    "unmarshal map key float32",
+			name:  "unmarshal map key float32",
 			input: `{"1.2":1.8}`,
 			expected: &map[float32]float32{
-				1.2:  1.8,
+				1.2: 1.8,
 			},
 			newfn: func() interface{} { return new(map[float32]float32) },
 		},
@@ -54,7 +54,11 @@ func TestIssue747(t *testing.T) {
 			assert.Equal(t, tt.expected, sv)
 			assert.NoError(t, serr)
 
-			// Note: it is different from encoding/json 
+			if stdUsesJSONV2 {
+				return
+			}
+
+			// Note: it is different from legacy encoding/json.
 			jerr := json.Unmarshal([]byte(tt.input), &jv)
 			assert.NotEqual(t, jerr == nil, serr == nil)
 			assert.NotEqual(t, jv, sv)
diff --git a/issue_test/issue758_test.go b/issue_test/issue758_test.go
index f753c9329..0db7fce27 100644
--- a/issue_test/issue758_test.go
+++ b/issue_test/issue758_test.go
@@ -6,9 +6,15 @@ import (
 	"github.com/bytedance/sonic"
 )
 
-
 func TestIssue758_UnmarshalIntoAnyPointer(t *testing.T) {
-	for _, cas := range []unmTestCase {
+	// The "recursive" self-referential eface cases make the std encoding/json
+	// jsonv2 backend recurse until stack overflow, which aborts the whole test
+	// binary. Sonic handles them, but the test compares against the live std
+	// reference, so skip under v2. See docs/json-v2-alignment.md.
+	if stdUsesJSONV2 {
+		t.Skip("std encoding/json jsonv2 backend stack-overflows on self-referential eface; sonic follows v1")
+	}
+	for _, cas := range []unmTestCase{
 		{
 			name: "non-nil typed pointer",
 			data: []byte(`["one","2"]`),
@@ -52,10 +58,10 @@ func TestIssue758_UnmarshalIntoAnyPointer(t *testing.T) {
 			name: "non-nil eface pointer",
 			data: []byte(`{"a": "b"}`),
 			newfn: func() interface{} {
-				var v1 interface{} = & struct {
+				var v1 interface{} = &struct {
 					A string `json:"a"`
 					B string `json:"b"`
-				} {
+				}{
 					A: "c",
 					B: "d",
 				}
@@ -113,8 +119,7 @@ func TestIssue758_UnmarshalIntoAnyPointer(t *testing.T) {
 			name: "non-nil iface type as struct field",
 			data: []byte(`{"id": {"id": "2"},"name": "name"}`),
 			newfn: func() interface{} {
-				obj := WrapperEface {
-				}
+				obj := WrapperEface{}
 				foo := fooEface{}
 				obj.Id = &foo
 				return &obj
@@ -124,8 +129,7 @@ func TestIssue758_UnmarshalIntoAnyPointer(t *testing.T) {
 			name: "non-nil iface type as struct field",
 			data: []byte(`{"name": "name", "id": null}`),
 			newfn: func() interface{} {
-				obj := WrapperEface {
-				}
+				obj := WrapperEface{}
 				a := "123"
 				foo := fooEface{
 					Id: &a,
@@ -142,8 +146,8 @@ func TestIssue758_UnmarshalIntoAnyPointer(t *testing.T) {
 }
 
 type WrapperEface struct {
-	Name string `json:"name"`
-	Id MockEface `json:"id"`
+	Name string    `json:"name"`
+	Id   MockEface `json:"id"`
 }
 
 type MockEface interface {
@@ -165,5 +169,3 @@ type fooEface3 struct {
 func (self fooEface3) MyMock() {
 
 }
-
-
diff --git a/issue_test/issue772_test.go b/issue_test/issue772_test.go
index 43a1f6441..d71662826 100644
--- a/issue_test/issue772_test.go
+++ b/issue_test/issue772_test.go
@@ -1,4 +1,3 @@
-
 package issue_test
 
 import (
@@ -8,13 +7,15 @@ import (
 )
 
 func TestIssue772_SkipIfaceType(t *testing.T) {
-	for _, cas := range []unmTestCase {
+	if stdUsesJSONV2 {
+		t.Skip("std encoding/json jsonv2 backend differs for this legacy parity case; see docs/json-v2-alignment.md")
+	}
+	for _, cas := range []unmTestCase{
 		{
 			name: "should skip non-ptr iface type",
 			data: []byte(`{"id": {"id": "2"},"name": "name"}`),
 			newfn: func() interface{} {
-				obj := WrapperEface {
-				}
+				obj := WrapperEface{}
 				obj.Id = fooEface3{}
 				return &obj
 			},
@@ -23,8 +24,7 @@ func TestIssue772_SkipIfaceType(t *testing.T) {
 			name: "should skip nil iface type",
 			data: []byte(`{"id": {"id": "2"},"name": "name"}`),
 			newfn: func() interface{} {
-				obj := WrapperEface {
-				}
+				obj := WrapperEface{}
 				obj.Id = (*fooEface)(nil)
 				return &obj
 			},
@@ -35,6 +35,3 @@ func TestIssue772_SkipIfaceType(t *testing.T) {
 		})
 	}
 }
-
-
-
diff --git a/issue_test/issue824_test.go b/issue_test/issue824_test.go
index 3b94778c5..55c5222c0 100644
--- a/issue_test/issue824_test.go
+++ b/issue_test/issue824_test.go
@@ -26,6 +26,12 @@ import (
 
 func TestFloatMap(t *testing.T) {
 	js, err := sonic.ConfigStd.Marshal(map[float64]string{1: ""})
+
+	if stdUsesJSONV2 {
+		require.Error(t, err)
+		return
+	}
+
 	js0, err0 := json.Marshal(map[float64]string{1: ""})
 	require.Equal(t, err0 == nil, err == nil)
 	require.Equal(t, string(js0), string(js))
diff --git a/issue_test/issue827_test.go b/issue_test/issue827_test.go
index bcb70766d..f54781a22 100644
--- a/issue_test/issue827_test.go
+++ b/issue_test/issue827_test.go
@@ -144,27 +144,35 @@ func TestIssue827_AllTextMarshalerTypes(t *testing.T) {
 		{"string3", map[Str2TM]int{s1: 1, s2: 2}},
 		{"custom", map[CustomTM]int{nil: 1, make(chan int): 2}},
 	}
-	
+
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			jsonData, err := json.Marshal(tc.data)
-			require.NoError(t, err)
-			expected := string(jsonData)
-			println(tc.name, "expected:", expected)
-			
 			sonicData, err := sonic.Marshal(tc.data)
 			require.NoError(t, err)
-			
+
 			sonicStdData, err := sonic.ConfigStd.Marshal(tc.data)
 			require.NoError(t, err)
-			require.Equal(t, expected, string(sonicStdData))
 
-			// compare the output of sonic.Marshal
-			var sonicMap, jsonMap map[string]int
+			var sonicMap, sonicStdMap map[string]int
 			require.NoError(t, json.Unmarshal(sonicData, &sonicMap))
+			require.NoError(t, json.Unmarshal(sonicStdData, &sonicStdMap))
+			require.Equal(t, sonicStdMap, sonicMap)
+
+			if stdUsesJSONV2 {
+				return
+			}
+
+			jsonData, err := json.Marshal(tc.data)
+			require.NoError(t, err)
+			expected := string(jsonData)
+			println(tc.name, "expected:", expected)
+
+			require.Equal(t, expected, string(sonicStdData))
+
+			var jsonMap map[string]int
 			require.NoError(t, json.Unmarshal(jsonData, &jsonMap))
 			require.Equal(t, jsonMap, sonicMap)
-			
+
 		})
 	}
 }
diff --git a/issue_test/jsonv1_compat_test.go b/issue_test/jsonv1_compat_test.go
new file mode 100644
index 000000000..1c51e8151
--- /dev/null
+++ b/issue_test/jsonv1_compat_test.go
@@ -0,0 +1,26 @@
+//go:build !goexperiment.jsonv2
+// +build !goexperiment.jsonv2
+
+/*
+ * Copyright 2021 ByteDance Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package issue_test
+
+// stdUsesJSONV2 reports whether the standard library encoding/json package is
+// using the json v2 backend. It is false here: either Go < 1.27, or the
+// experiment was disabled with GOEXPERIMENT=nojsonv2. See
+// docs/json-v2-alignment.md.
+const stdUsesJSONV2 = false
diff --git a/issue_test/jsonv2_compat_test.go b/issue_test/jsonv2_compat_test.go
new file mode 100644
index 000000000..a1cedec50
--- /dev/null
+++ b/issue_test/jsonv2_compat_test.go
@@ -0,0 +1,27 @@
+//go:build goexperiment.jsonv2
+// +build goexperiment.jsonv2
+
+/*
+ * Copyright 2021 ByteDance Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package issue_test
+
+// stdUsesJSONV2 reports whether the standard library encoding/json package is
+// using the json v2 backend. This is the default since Go 1.27 (opt out with
+// GOEXPERIMENT=nojsonv2). Sonic still implements v1 semantics, so tests that
+// assert exact std parity gate those assertions in this mode. See
+// docs/json-v2-alignment.md for the divergence list.
+const stdUsesJSONV2 = true
diff --git a/loader/funcdata_compat.go b/loader/funcdata_compat.go
index 68d50a663..a2764866e 100644
--- a/loader/funcdata_compat.go
+++ b/loader/funcdata_compat.go
@@ -1,5 +1,5 @@
-//go:build !go1.17 || go1.27
-// +build !go1.17 go1.27
+//go:build !go1.17 || go1.28
+// +build !go1.17 go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/loader/funcdata_go127.go b/loader/funcdata_go127.go
new file mode 100644
index 000000000..5fb6e8799
--- /dev/null
+++ b/loader/funcdata_go127.go
@@ -0,0 +1,129 @@
+//go:build go1.27 && !go1.28
+// +build go1.27,!go1.28
+
+/*
+ * Copyright 2021 ByteDance Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package loader
+
+import (
+	"github.com/bytedance/sonic/loader/internal/rt"
+	"unsafe"
+)
+
+const (
+	_Magic uint32 = 0xFFFFFFF1
+)
+
+// In Go 1.27 the moduledata layout changed (CL around the type/itab linker rework):
+//   - `types, etypes` gained a `typedesclen` field in between;
+//   - `itaboffset, itabsize` were added after etypes;
+//   - the `typelinks []int32` and `itablinks []*itab` slices were removed;
+//   - `typemap` was retyped from map[typeOff]*_type to map[*_type]*_type.
+//
+// See runtime/symtab.go in the go1.27 release branch.
+type moduledata struct {
+	pcHeader     *pcHeader
+	funcnametab  []byte
+	cutab        []uint32
+	filetab      []byte
+	pctab        []byte
+	pclntable    []byte
+	ftab         []funcTab
+	findfunctab  uintptr
+	minpc, maxpc uintptr // first func address, last func address + last func size
+
+	text, etext                uintptr // start/end of text, (etext-text) must be greater than MIN_FUNC
+	noptrdata, enoptrdata      uintptr
+	data, edata                uintptr
+	bss, ebss                  uintptr
+	noptrbss, enoptrbss        uintptr
+	covctrs, ecovctrs          uintptr
+	end, gcdata, gcbss         uintptr
+	types, typedesclen, etypes uintptr
+	itaboffset, itabsize       uintptr
+	rodata                     uintptr
+	gofunc                     uintptr // go.func.* is actual funcinfo object in image
+	epclntab                   uintptr
+
+	textsectmap []textSection // see runtime/symtab.go: textAddr()
+
+	ptab []ptabEntry
+
+	pluginpath string
+	pkghashes  []modulehash
+
+	// This slice records the initializing tasks that need to be
+	// done to start up the program. It is built by the linker.
+	inittasks []unsafe.Pointer
+
+	modulename   string
+	modulehashes []modulehash
+
+	hasmain uint8 // 1 if module contains the main function, 0 otherwise
+	bad     bool  // module failed to load and should be ignored
+
+	gcdatamask, gcbssmask bitVector
+
+	typemap map[*rt.GoType]*rt.GoType // *_type to use from previous module
+
+	next *moduledata
+}
+
+type _func struct {
+	entryOff uint32 // start pc, as offset from moduledata.text/pcHeader.textStart
+	nameOff  int32  // function name, as index into moduledata.funcnametab.
+
+	args        int32  // in/out args size
+	deferreturn uint32 // offset of start of a deferreturn call instruction from entry, if any.
+
+	pcsp      uint32
+	pcfile    uint32
+	pcln      uint32
+	npcdata   uint32
+	cuOffset  uint32 // runtime.cutab offset of this function's CU
+	startLine int32  // line number of start of function (func keyword/TEXT directive)
+	funcID    uint8  // set for certain special runtime functions
+	flag      uint8
+	_         [1]byte // pad
+	nfuncdata uint8   //
+
+	// The end of the struct is followed immediately by two variable-length
+	// arrays that reference the pcdata and funcdata locations for this
+	// function.
+
+	// pcdata contains the offset into moduledata.pctab for the start of
+	// that index's table. e.g.,
+	// &moduledata.pctab[_func.pcdata[_PCDATA_UnsafePoint]] is the start of
+	// the unsafe point table.
+	//
+	// An offset of 0 indicates that there is no table.
+	//
+	// pcdata [npcdata]uint32
+
+	// funcdata contains the offset past moduledata.gofunc which contains a
+	// pointer to that index's funcdata. e.g.,
+	// *(moduledata.gofunc +  _func.funcdata[_FUNCDATA_ArgsPointerMaps]) is
+	// the argument pointer map.
+	//
+	// An offset of ^uint32(0) indicates that there is no entry.
+	//
+	// funcdata [nfuncdata]uint32
+}
+
+func setEpclntab(mod *moduledata, val uintptr) {
+	mod.epclntab = val
+}
diff --git a/loader/moduledata.go b/loader/moduledata.go
index 7a22c04a3..98597eb51 100644
--- a/loader/moduledata.go
+++ b/loader/moduledata.go
@@ -1,5 +1,5 @@
-// go:build go1.18 && !go1.27
-// +build go1.18,!go1.27
+//go:build go1.18 && !go1.28
+// +build go1.18,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/rfc_test.go b/rfc_test.go
index 82cc704c0..0210fbbfe 100644
--- a/rfc_test.go
+++ b/rfc_test.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 package sonic_test
 
diff --git a/scripts/test_pcsp.py b/scripts/test_pcsp.py
index 04c2baa81..26fa38faf 100755
--- a/scripts/test_pcsp.py
+++ b/scripts/test_pcsp.py
@@ -63,7 +63,7 @@ def check_ge_go_1_23() -> bool:
     if ver is None:
         print("Cannot get go version")
         exit(1)
-    major, minor, _ = ver.split('.')
+    major, minor = ver.split('.')[:2]
     return int(major) > 1 or int(minor) >= 23
 
 def main():
diff --git a/search_test.go b/search_test.go
index c9248b917..3ad240d80 100644
--- a/search_test.go
+++ b/search_test.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/sonic.go b/sonic.go
index c6a825ab2..95a1c69c5 100644
--- a/sonic.go
+++ b/sonic.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/unquote/unquote.go b/unquote/unquote.go
index fa18b631e..644e793f4 100644
--- a/unquote/unquote.go
+++ b/unquote/unquote.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/unquote/unquote_fallback.go b/unquote/unquote_fallback.go
index 81a5bfca4..f9fcaf59b 100644
--- a/unquote/unquote_fallback.go
+++ b/unquote/unquote_fallback.go
@@ -1,5 +1,5 @@
-//go:build (!amd64 && !arm64) || go1.27 || !go1.17 || (arm64 && !go1.20)
-// +build !amd64,!arm64 go1.27 !go1.17 arm64,!go1.20
+//go:build (!amd64 && !arm64) || go1.28 || !go1.17 || (arm64 && !go1.20)
+// +build !amd64,!arm64 go1.28 !go1.17 arm64,!go1.20
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/utf8/utf8.go b/utf8/utf8.go
index 3ed307168..b48c5cb6e 100644
--- a/utf8/utf8.go
+++ b/utf8/utf8.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2022 ByteDance Inc.
diff --git a/utf8/utf8_fallback.go b/utf8/utf8_fallback.go
index b3d0ddee0..25c337e87 100644
--- a/utf8/utf8_fallback.go
+++ b/utf8/utf8_fallback.go
@@ -1,5 +1,5 @@
-//go:build (!amd64 && !arm64) || go1.27 || !go1.17 || (arm64 && !go1.20)
-// +build !amd64,!arm64 go1.27 !go1.17 arm64,!go1.20
+//go:build (!amd64 && !arm64) || go1.28 || !go1.17 || (arm64 && !go1.20)
+// +build !amd64,!arm64 go1.28 !go1.17 arm64,!go1.20
 
 /*
  * Copyright 2021 ByteDance Inc.
diff --git a/utf8/utf8_native_test.go b/utf8/utf8_native_test.go
index 1d7c7a326..4fd6bc673 100644
--- a/utf8/utf8_native_test.go
+++ b/utf8/utf8_native_test.go
@@ -1,5 +1,5 @@
-//go:build (amd64 && go1.17 && !go1.27) || (arm64 && go1.20 && !go1.27)
-// +build amd64,go1.17,!go1.27 arm64,go1.20,!go1.27
+//go:build (amd64 && go1.17 && !go1.28) || (arm64 && go1.20 && !go1.28)
+// +build amd64,go1.17,!go1.28 arm64,go1.20,!go1.28
 
 /*
  * Copyright 2022 ByteDance Inc.