Skip to content

docs

Directory actions

More options

Directory actions

More options

Latest commit

 

History

History

docs

README.md

AstraSend — Uniswap v4 Hook Incubator Submission (UHI8)

Low-cost, compliant, group-funded cross-border remittances — powered by Uniswap v4 hooks on Base and Unichain.

Live App · Demo Video

The Problem

Remittances are one of the most important financial flows in the world. In 2023, over $860 billion was sent across borders by migrant workers supporting families at home. Yet the average global fee remains 6.2% (World Bank, Q4 2023) — meaning for every $100 sent, only $93.80 arrives. On corridors like US→Nigeria or US→Philippines, fees can hit 10–15%.

Beyond fees, the current system imposes:

  • 1–5 business day settlement through correspondent banking
  • Business-hours-only availability
  • $50–$100 minimum sends that exclude the smallest and most critical transfers
  • No group funding — a family cannot collectively send money for a loved one's tuition or medical bill
  • Opaque FX markups hidden in mid-market rate spreads
  • Bureaucratic KYC that excludes unbanked recipients

AstraSend attacks every one of these pain points using Uniswap v4's hook architecture.

The Solution

AstraSend is a Uniswap v4 hook that transforms any USDT/X liquidity pool into a compliant remittance corridor. Senders contribute to on-chain escrow contracts — either directly or passively through Uniswap swaps — and recipients receive funds automatically when the target is met.

Key capabilities:

Capability How it works
< 1% total fee 0.5% platform fee + sub-cent gas on Base/Unichain L2
~2s settlement on Base, ~200ms on Unichain L2 finality, no correspondent banking
Group contributions Multiple senders pool toward one remittance
Phone-based sends Send to a phone number — no wallet address needed
Auto-release escrow Funds released automatically when target is met
On-chain compliance Pluggable KYC/AML modules — no bureaucratic paperwork
Expiry & refunds Trustless, instant refunds if target not met
24/7 availability Blockchain has no business hours

Why Uniswap v4 Hooks?

AstraSend uses v4's hook architecture in a way that is impossible to build on v3 or any prior DEX version:

  1. afterSwapReturnDelta — The hook intercepts swap output before it reaches the swapper, redirecting USDT into the escrow. This is the financial primitive that makes "contribute via swap" possible without any wrapper contract.

  2. beforeSwap — Validates compliance and caches the remittance ID in EIP-1153 transient storage, passing context to afterSwap with zero cold storage reads.

  3. beforeAddLiquidity — Compliance-gates liquidity provision so only verified participants can provide liquidity to regulated remittance corridors.

  4. beforeDonate — Routes Uniswap v4 pool donations directly to active remittance escrows, enabling a completely new "donate-to-remit" flow.

  5. afterInitialize — Registers each new pool as a USDT corridor and validates it contains the supported token.

No existing remittance protocol uses DeFi liquidity this directly. AstraSend doesn't just sit beside a DEX — it is the DEX. Every swap on a registered pool can be a remittance contribution.

Hook Architecture Summary

Sender Wallet
     │
     ▼
Uniswap v4 PoolManager
     │
     ├── beforeSwap ──────► Compliance check + tstore(remittanceId)
     │
     ├── afterSwap ───────► tload(remittanceId) → take(USDT) → escrow
     │                      ↑ afterSwapReturnDelta captures output
     ├── beforeAddLiquidity ► Compliance gate for LPs
     │
     ├── afterInitialize ──► Register pool as USDT corridor
     │
     └── beforeDonate ────► Route donations to active remittance

Deployed Contracts

Base Sepolia (Chain ID: 84532)

Contract Address
AstraSendHook 0x3E2c98Aa25Ac5a96126e07458ff4F27b5A9aD8e4
OpenCompliance 0xa15d7d5505BC3D7B74A27808141D86752EfE09b6
PhoneNumberResolver 0x29f47d33B73712000f554FAB4119eE6ce0741Dea
USDT (MockUSDT) 0x1754e1dBc66a0997D0442D7a24DB149d494F6FcA

Unichain Sepolia (Chain ID: 1301)

Contract Address
AstraSendHook 0x31c76772ad6A821F0908AC3c6Caa706a043A98E4
OpenCompliance 0xBfBD571aCA171167833355e944c5CC8E96FE8A16
PhoneNumberResolver 0x1754e1dBc66a0997D0442D7a24DB149d494F6FcA
USDT (MockUSDT) 0x3E4e5a1Fb92f70dB37019F3E813C79341ede37E6

Live Demo

Frontend: deployed on Base Sepolia + Unichain Sepolia testnets.

  • Connect wallet → create a remittance → share the ID → friends contribute → recipient auto-receives.
  • Register a phone number → anyone can send to your + number without knowing your wallet address.

Test Coverage

229 passing tests covering:

  • Unit tests for all remittance lifecycle operations
  • Integration tests for hook paths (afterInitialize, beforeAddLiquidity, beforeSwap/afterSwap, beforeDonate)
  • Invariant tests (solvency, contribution accounting)
  • Fuzz tests (contribution amounts, expiry timestamps, contributor counts)

Repository Structure

AstrasendHook/
├── src/
│   ├── AstraSendHook.sol           # Main hook contract
│   ├── compliance/
│   │   ├── OpenCompliance.sol      # Testnet: permissionless + blocklist
│   │   ├── AllowlistCompliance.sol # Phase 1: KYC allowlist
│   │   ├── WorldcoinCompliance.sol # Phase 2: World ID biometric
│   │   └── PhoneNumberResolver.sol # Phone hash → wallet mapping
│   ├── interfaces/                 # ICompliance, IAstraSendHook, etc.
│   └── libraries/RemitTypes.sol    # Shared structs, events, enums
├── test/                           # 229 tests
├── script/                         # Deployment scripts
├── frontend/                       # Next.js 16 + wagmi v3 + connectkit
└── docs/                           # This documentation

Documentation Index