About OpenAPI → TypeScript

Generate TypeScript interfaces from an OpenAPI schema. Part of the DevTools Surf developer suite. Browse more tools in the Developer Utilities collection.

Use Cases

• Frontend teams generating type-safe API client code
• Backend developers ensuring API contracts match implementations
• SDK authors automating client library generation from specs
• Full-stack teams sharing types between server and client codebases

Tips

• Generate interfaces for request bodies and response types
• Use readonly modifiers for immutable response properties
• Include enum types from OpenAPI string enumerations

Fun Facts

• OpenAPI started as Swagger, created by Tony Tam at Wordnik in 2011 — SmartBear acquired it in 2015 and donated the specification to the Linux Foundation as OpenAPI.
• The OpenAPI 3.1 specification, released in 2021, achieved full alignment with JSON Schema, resolving years of subtle incompatibilities between the two standards.
• TypeScript's type system is Turing-complete — you can technically encode a full OpenAPI schema as a type-level program, which projects like ts-rest and zodios exploit.

FAQ

Does it support OpenAPI 3.x?

3.0 and 3.1 both. OpenAPI 2 (Swagger) needs conversion first — use the Swagger editor's built-in v2→v3 converter.

What does it generate?

TypeScript interfaces for every schema, plus optional API client types for fetch/axios. Operations become typed function signatures.

Fetch client or just types?

Toggle — types only (use with your own client) or a full fetch-based client. For Zod-validated clients, pair with the json-to-zod tool.

How does it handle allOf/oneOf?

allOf → intersection type. oneOf → union type. discriminator keys produce type guards automatically.