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Overview

typed-api-spec is an TypeScript based declarative API specification.

Features​

TypeScript based API Specification​

You can define your API specification using TypeScript. No need to use yaml, json, or any other format.

type Spec = DefineApiEndpoints<{
  "/users": {
    get: {
      responses: { 200: { body: { userNames: string[] }; }; };
    };
  };
}>;

See API Specification page for more details.

Type-safe, zero-runtime API client​

typed-api-spec provides strict typed fetch. For example, if you define API response schema by API Specification, you can get the typed response data. It is just native fetch, so:

  • zero runtime: 0kb bundle size
  • zero dependencies
  • zero learning cost
const fetchT = fetch as FetchT<"", Spec>;
const res = await fetchT("/users");
const data = await res.json(); // data is { userNames: string[] }

See Client page for more details.

Server Framework & Validation library integration​

typed-api-spec can be integrated with various server frameworks(like Express, Fastify) and validation libraries(like zod, Valibot).

See Server and Validation page for more details.