apical-ts - Yet Another OpenAPI to Zod/TypeScript Generator

[gunzip]

apical-ts, OpenAPI to Zod/TypeScript Generator

apical-ts is an opinionated TypeScript code generator that creates type-safe structures from OpenAPI specifications. I've built this to directly address common issues with existing tools by focusing on strictness and comprehensive runtime validation.

What it Generates

1. Strict Zod v4 Schemas

It generate Zod v4 schemas from your OpenAPI models. The goal is to provide complete runtime validation for your API structures.

• Idiomatic Zod: The generation includes features to handle complex cases in an idiomatic Zod way. For example, it supports circular structures (self-referencing types) using getters to prevent immediate stack overflows during schema definition.

2. Type-Safe API Client

A fully-typed REST API client is generated, ensuring that requests and responses align with the specification, catching most errors at build time.

• Precise Error Handling: The client leverages discriminated unions to provide fine-grained control over HTTP statuses and content types. This allows users to handle successful responses and various error states (e.g., $200$, $400$, $404$, etc.) with complete type safety.

3. Validating Server Wrappers

It generates server-side wrappers which users can integrate in any framework (Express, Hono, etc.) that automatically hook up the generated Zod schemas. These wrappers handle the validation of incoming request parameters (body, query, path) before they reach the main route handler.

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A Note on Project Status

This project is actively developed and is currently in the process of stabilizing the developer experience (DX) and the core interfaces. While it is already functioning and generating decent code, the tool's interface is subject to change in its path towards a stable release. Welcome users who are comfortable with a project in development!

Check out the documentation and get started: https://gunzip.github.io/apical-ts/ or play with StackBlitz demo