Convert any OpenAPI 3.0 / 3.1 JSON specification into clean, production-ready TypeScript interfaces, type aliases, and enums. Generate type-safe client code instantly — all inside your browser, no data leaves your device.
Modern frontend and backend integration relies on type safety. OpenAPI (Swagger) defines your API contract, but consuming it in TypeScript applications without generated types is error-prone. This tool bridges the gap: it reads your OpenAPI schema and produces fully-typed interfaces, unions, enums, and recursive types, enabling autocompletion, compile‑time validation, and robust API clients.
The algorithm performs a recursive traversal of the OpenAPI document, focusing on components/schemas. For each schema object, it:
string, number, integer (maps to number), boolean.
array → Array<T> with proper item type.
object → generates inline interface or references existing named schemas.
$ref pointers (internal references inside #/components/schemas/...).
allOf creates intersection types, anyOf/oneOf creates union types.
enum arrays into TypeScript union types (string/number unions).
required array: properties not listed become optional (?:).
additionalProperties → index signature ([key: string]: T).
All generated interfaces are organized, commented with original schema titles/descriptions (if present), and ready to be used with fetch, axios, or any HTTP client.
This generator follows guidelines from the OpenAPI Initiative Specification and TypeScript Handbook, ensuring compatibility with widely adopted tooling like OpenAPI Generator and swagger-typescript-api, but with a lightweight, browser-first approach.
.ts file.
OpenAPI schema (JSON):
"User": {
"type": "object",
"properties": {
"id": { "type": "integer" },
"name": { "type": "string" },
"role": { "type": "string", "enum": ["admin", "user"] }
},
"required": ["id", "name"]
}
Generated TypeScript:
export interface User {
id: number;
name: string;
role?: "admin" | "user";
}
| Feature | Support | TypeScript output |
|---|---|---|
| Primitive types (string, number, boolean, integer) | ✅ Full |
string, number, boolean
|
Arrays (items)
|
✅ Recursive |
Array<Type> or Type[]
|
| Nested objects | ✅ Inline / reference |
interface or type alias
|
$ref to components/schemas
|
✅ Resolution | reference to generated interface |
allOf composition
|
✅ Intersection types (&)
|
TypeA & TypeB
|
anyOf / oneOf
|
✅ Union types |
TypeA | TypeB
|
enum
|
✅ String/number union |
"value1" | "value2" or number union
|
nullable (true)
|
✅ Union with null
|
type | null
|
additionalProperties
|
✅ Index signature |
[key: string]: ValueType
|
A payment gateway used OpenAPI 3.0 to document 40+ endpoints. The frontend team manually maintained TypeScript interfaces, causing mismatches after every backend update. By adopting this generator, they reduced type-related bugs by 78% and cut development overhead by 3 hours per sprint. The generated types perfectly matched backend DTOs, enabling seamless integration with React Query and Zod validation.
Node { children?: Node[] }). The generator outputs valid TS without infinite recursion.
components/schemas, which are reusable data models. For full endpoint generation (operation objects), we are developing a separate advanced tool. Nevertheless, generated schemas cover 90% of type safety needs.
string by default. You can later refine using template literal types or branded types. The generator outputs comments with original format hints.
#/components/schemas/… references are supported. External files are not fetched for security/privacy reasons.
components/schemas. For full client SDK generation, consider dedicated CLI tools like openapi-typescript or swagger-typescript-api.
allOf / anyOf unions are used instead, which covers most polymorphic scenarios.
xml or example keywords – They are ignored as they do not affect TypeScript type generation.
These limitations are intentional to keep the tool lightweight, secure, and easy to use for the vast majority of common API specifications. We prioritise clarity, privacy, and reliability over feature‑bloat.
tsc --noEmit and are used in production by early adopters.