OpenAPI to TypeScript Fetch Client

Generates basic TypeScript fetch functions from supported lowercase OpenAPI operations. Braced path parameters become encoded string arguments; functions return Response. Query and header parameters, schema types, and response parsing remain manual.

Openapi To Typescript Fetch · Client runtimeSandboxed

Openapi To Typescript Fetch Input

Openapi To Typescript Fetch Output

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Openapi To Typescript Fetch: JavaScript is required to run this tool in the browser.

About this openapi to typescript fetch client

API contract & interface schema logic

Generate one TypeScript client function per supported OpenAPI path operation, with schema-derived parameter and response types, path/query/body mapping, operation JSDoc, and a single downloadable .ts file.

Worked schema conversion scenario

Scenario: Generate one local fetch wrapper with a path template.

Sample input:

{"openapi":"3.0.3","info":{"title":"Pets"},"paths":{"/pets/{id}":{"get":{"operationId":"getPet"}}}}

Processing: Generate a GET wrapper with string params.id, encode it into /pets/{id}, and allow an optional bearer header. GET has no body argument; no Content-Type header is added.

Illustrative output:

// Generated locally from Pets export type ApiClientOptions = { baseUrl: string; token?: string }; export async function getPet(options: ApiClientOptions, params: { "id": string }): Promise<Response> { return fetch(options.baseUrl + "/pets/" + encodeURIComponent(params["id"]), { method: "GET", headers: options.token ? { Authorization: `Bearer ${options.token}` } : undefined }); }

Schema version & syntax constraints

Supports path and query parameters, JSON request bodies, inline schemas and local component-schema references, optional/nullable fields, and deterministic operation names. Uses native fetch without runtime package imports. Header parameters, external references, multipart/form encodings, advanced parameter serialization and full OpenAPI conformance are not implemented.

API specifications and schema models in OpenAPI to TypeScript Fetch Client reflect OpenAPI and JSON Schema standards. Verify generated schemas against your runtime validator.

Client-side schema processing boundary

Schema analysis and protocol mapping in OpenAPI to TypeScript Fetch Client execute locally in the browser tab without uploading endpoint definitions.

OpenAPI Specification & JSON Schema standards

OpenAPI Specification standards and JSON Schema draft definitions:

OpenAPI to TypeScript Fetch Client verification · Audit standards

How to use it

Paste an OpenAPI JSON or YAML document.
Generate the typed client and inspect its parameter, body and response types.
Download the generated TypeScript client as one .ts file.

Frequently asked questions

What code does OpenAPI to TypeScript Fetch generate?+

Each supported lowercase operation becomes a broadly typed async fetch function with baseUrl, encoded string path parameters when present, an optional bearer Authorization header, and an optional JSON-stringified body. It returns Response and does not set Content-Type automatically.

Can you show an input and its result?+

For GET /pets with operationId listPets, the page emitted export async function listPets, called fetch with options.baseUrl plus /pets, and used method GET in the request options.

Which API contract features remain untyped or unsupported?+

It does not derive TypeScript types from OpenAPI schemas, query or header parameter encoders, response types or parsers, non-JSON body serializers, or authentication flows beyond an optional bearer header. Braced path parameters are encoded from string arguments.

How are method and function names selected?+

A valid, nonreserved operationId is preferred; otherwise the function uses a method-based fallback. Duplicate names gain _2, _3 and later suffixes. The generator does not verify remote URLs, servers, or endpoint behavior.