OpenAPI to TypeScript Generator

This tool supports OpenAPI 3.x specs (which use components.schemas) and Swagger 2.x specs (which use definitions). Both YAML and JSON input formats are accepted. For OpenAPI 3.x, paste the full spec or just the components section. The generator reads the schemas section and produces a TypeScript interface for each object schema. Schemas referencing external files ($ref with http:// or file paths) are not resolved — only internal #/components/schemas/Name references work.

$ref values like '#/components/schemas/Pet' are converted to direct TypeScript type references. If Pet is defined as an interface, your field will be typed as Pet (not inlined). This means the generated interfaces reference each other by name, which is how TypeScript expects it — you get a clean, composable set of interfaces rather than deeply nested anonymous types. Circular references (Schema A referencing Schema B which references Schema A) will generate valid TypeScript since interfaces are just type declarations.

In OpenAPI, the required array at the object level lists which properties are mandatory. This tool maps required properties to TypeScript required fields (field: Type) and non-required properties to optional fields (field?: Type). This matches the TypeScript convention where ? means the property may be absent. Note that OpenAPI's nullable: true is separate from required — a field can be required but nullable (must be present, but its value may be null), which maps to field: Type | null.

Yes — copy the output and paste it into a .ts or .d.ts file in your project. The generated code uses only built-in TypeScript syntax with no imports required. For a better long-term workflow, consider tools like openapi-typescript (npm package) for CI/CD integration that keeps your types in sync as your API spec evolves. This browser tool is ideal for quick one-off conversions, prototyping, or when you don't want to add a build step. The output is compatible with TypeScript 4.x and 5.x.