What is Openapi To Typescript Generator
The OpenAPI to TypeScript Generator is a client-side tool that parses an OpenAPI 3.x specification and generates a TypeScript interface defining client methods for each endpoint. When you paste a valid OpenAPI spec (with at least a paths object containing endpoint definitions), the tool iterates over every path and HTTP method, generates a method name by combining the method and path (e.g., getUsersByUserId for GET /users/{userId}), and outputs a TypeScript interface where each method accepts an optional params object and returns Promise<unknown>. The generated interface serves as a starting point for typed API clients — you would typically extend it with specific parameter and response types from the schema's components section. The tool handles path parameters (expressed as {param} in OpenAPI) by converting them to camelCase method names, and skips non-HTTP operations. The output is a clean TypeScript interface ready to paste into your project. The generator handles nested path parameters (e.g., /users/{id}/posts/{postId}) by concatenating parameter names in camelCase. It also skips operations that do not map to standard HTTP methods, ensuring the output contains only actionable endpoint methods.
How to Use Openapi To Typescript Generator
- Step 1: Copy your OpenAPI 3.x specification as JSON and paste it into the input textarea. The spec must include a top-level paths object with at least one endpoint definition.
- Step 2: Click Transform. The tool parses the spec and generates a TypeScript interface named ApiClient.
- Step 3: The output shows the interface with a method for each endpoint. Method names are derived from the HTTP method and path: GET /users/{id} becomes getUsersById, POST /orders becomes postOrders, etc.
- Step 4: Copy the interface into your TypeScript project and extend it with specific parameter types and response types from the spec's components/schemas section.
Why Use Openapi To Typescript Generator
Writing TypeScript types for API endpoints is tedious when you have dozens or hundreds of endpoints defined in an OpenAPI spec. The generator creates a typed scaffold that you can extend with specific types, saving the mechanical work of translating each path and method into a TypeScript method signature. The generated method names follow a consistent convention (method + path in camelCase), which helps maintain a uniform API client interface. This is particularly valuable when starting a new frontend project that consumes an existing API — paste the spec, get the interface, add response types, and you have a typed API client in minutes.
Privacy & Security
This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.
Frequently Asked Questions
Does it generate full type definitions?
<p>The tool generates the method signatures with params: unknown and return type Promise<unknown>. For full typing, you would need to extend the interface with specific parameter types and response types from the spec's components/schemas section.</p>
Which OpenAPI versions are supported?
<p>The tool supports OpenAPI 3.x specifications with a paths object. Swagger 2.0 specs (which use a different structure) would need to be converted to OpenAPI 3.x first.</p>
Can I customize the generated method names?
<p>The method names are generated automatically from the HTTP method and path. You can rename them after generation to match your preferred naming convention.</p>
Does it support polymorphic responses?
<p>The tool generates Promise<unknown> return types for all methods. For polymorphic responses (oneOf, anyOf), you would need to manually type the response using the schema definitions from the spec.</p>