Generate TypeScript types from OpenAPI

Parse any OpenAPI 3.x specification and generate TypeScript interfaces or Zod schemas for all schemas — from a local file or a remote URL, in one command.

Installation

npm install -D snaptype

Requires Node.js 20+. ESM only.

Basic usage

By default, snaptype generates one file per schema — provide a directory as output. Use --single-file to combine everything into one file.

snaptype from-openapi <source> [options]
# One file per schema — output must be a directory
snaptype from-openapi ./openapi.yaml -o ./src/types/

# All schemas in a single file
snaptype from-openapi ./openapi.yaml --single-file -o ./src/api-types.ts

# Remote spec (URL)
snaptype from-openapi https://petstore3.swagger.io/api/v3/openapi.json -o ./types/

# With Zod schemas
snaptype from-openapi ./openapi.yaml --zod -o ./src/schemas/

Example

Given this OpenAPI spec fragment:

Download openapi.yaml
openapi.yaml
components:
  schemas:
    User:
      type: object
      required: [id, email]
      properties:
        id:
          type: integer
        email:
          type: string
          format: email
        role:
          type: string
          enum: [admin, user, moderator]
        address:
          $ref: '#/components/schemas/Address'

snaptype generates:

src/types/User.ts
export interface User {
  id: number;
  email: string;
  role?: "admin" | "user" | "moderator";
  address?: Address;
}

With --zod:

src/schemas/User.ts
import { z } from 'zod';

export const UserSchema = z.object({
  id: z.number(),
  email: z.email(),
  role: z.enum(["admin", "user", "moderator"]).optional(),
  address: AddressSchema.optional(),
});

export type User = z.infer<typeof UserSchema>;

What gets generated

OpenAPI constructTypeScript output
Request / response body schemasOne interface per schema
#/components/schemas/*One interface per component
oneOf / anyOfTypeScript union type (A | B | C)
allOfMerged flat object
enum valuesString literal union ("a" | "b")
required fieldsNon-optional properties
optional fieldsprop?: Type

Options

FlagDescription
--single-fileOutput all schemas into one file instead of one file per schema
--zodGenerate Zod schemas instead of (or alongside) TypeScript interfaces
--tsAlso emit TypeScript when --zod is set
-o, --output <path>Output directory (default) or file path with --single-file
-n, --naming <convention>Property naming: camel (default), pascal, snake
--readonlyAdd readonly to all properties
-c, --config <path>Path to .snaptyperc config file

CI/CD integration

Keep your TypeScript types in sync with your API contract by running snaptype in CI whenever the OpenAPI spec changes.

# GitHub Actions example
- name: Generate types from OpenAPI spec
  run: npx snaptype from-openapi ./openapi.yaml --single-file -o src/api-types.ts

- name: Fail if types are out of date
  run: git diff --exit-code src/api-types.ts
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