Orval – OpenAPI to TypeScript Code Generator

Orval generates type-safe TypeScript clients, hooks, schemas, mocks, and server handlers from OpenAPI v3/Swagger v2 specifications.

Quick Start

Installation

npm install orval -D
# or yarn add orval -D
# or pnpm add orval -D
# or bun add orval -D

Minimal Configuration

import { defineConfig } from 'orval';

export default defineConfig({
  petstore: {
    input: {
      target: './petstore.yaml',
    },
    output: {
      target: './src/api/petstore.ts',
      schemas: './src/api/model',
      client: 'react-query',
    },
  },
});

Run

npx orval
npx orval --config ./orval.config.ts
npx orval --project petstore
npx orval --watch

Choosing Your Setup

Client Selection Guide

Mode Selection Guide

• single — Everything in one file. Best for small APIs.
• split — Separate files: petstore.ts, petstore.schemas.ts, petstore.msw.ts. Good for medium APIs.
• tags — One file per OpenAPI tag + shared schemas. Organizes by domain.
• tags-split — Folder per tag with split files. Best for large APIs. Recommended.

httpClient Option

For react-query, vue-query, svelte-query, and swr clients:

output: {
  client: 'react-query',
  httpClient: 'fetch',  // 'fetch' (default) | 'axios'
}

For angular-query:

output: {
  client: 'angular-query',
  httpClient: 'angular',  // Uses Angular HttpClient
}

Configuration Reference

Config Structure

import { defineConfig } from 'orval';

export default defineConfig({
  [projectName]: {
    input: InputOptions,
    output: OutputOptions,
    hooks: HooksOptions,
  },
});

Multiple projects can share the same config file with different input/output settings.

Input Options

input: {
  target: './spec.yaml',              // Path or URL to OpenAPI spec (required)
  override: {
    transformer: './transform.js',    // Transform spec before generation
  },
  filters: {
    mode: 'include',                  // 'include' | 'exclude'
    tags: ['pets', /health/],         // Filter by OpenAPI tags
    schemas: ['Pet', /Error/],        // Filter by schema names
  },
  parserOptions: {
    headers: [                        // Auth headers for remote spec URLs
      {
        domains: ['api.example.com'],
        headers: {
          Authorization: 'Bearer YOUR_TOKEN',
          'X-API-Key': 'your-api-key',
        },
      },
    ],
  },
}

Output Options

output: {
  target: './src/api/endpoints.ts',     // Output path (required)
  client: 'react-query',               // Client type (see table above)
  httpClient: 'fetch',                  // 'fetch' (default) | 'axios' | 'angular'
  mode: 'tags-split',                   // 'single' | 'split' | 'tags' | 'tags-split'
  schemas: './src/api/model',           // Output path for model types
  operationSchemas: './src/api/params', // Separate path for operation-derived types
  workspace: 'src/',                    // Base folder for all files
  fileExtension: '.ts',                 // Custom file extension
  namingConvention: 'camelCase',        // File naming: camelCase | PascalCase | snake_case | kebab-case
  indexFiles: true,                     // Generate index.ts barrel files
  clean: true,                          // Clean output before generating
  prettier: true,                       // Format with Prettier
  biome: true,                          // Format with Biome
  headers: true,                        // Generate header parameters
  baseUrl: '/api/v2',                   // API base URL
  // or from spec:
  // baseUrl: { getBaseUrlFromSpecification: true, index: 0, variables: { environment: 'api.dev' } },
  mock: true,                           // Generate MSW handlers (boolean or config object)
  docs: true,                           // Generate TypeDoc documentation
  // docs: { configPath: './typedoc.config.mjs' },
  allParamsOptional: true,              // Make all params optional (except path params)
  urlEncodeParameters: true,            // URL-encode path/query parameters
  optionsParamRequired: false,          // Make options parameter required
  propertySortOrder: 'Specification',   // 'Alphabetical' | 'Specification'
  tsconfig: './tsconfig.json',          // Custom tsconfig path
  override: { ... },                    // Advanced overrides (see below)
}

Multiple API Specs

export default defineConfig({
  petstoreV1: {
    input: { target: './specs/v1.yaml' },
    output: { target: 'src/api/v1', client: 'react-query' },
  },
  petstoreV2: {
    input: { target: './specs/v2.yaml' },
    output: { target: 'src/api/v2', client: 'react-query' },
  },
});

Filter Endpoints

input: {
  target: './spec.yaml',
  filters: {
    mode: 'include',
    tags: ['pets'],
  },
}

Detailed Guides

When the user’s question involves a specific topic below, read the corresponding file from this skill’s directory.

OpenAPI Specification Best Practices

1. Use unique operationId for every operation — Orval uses these for function and hook names
2. Define reusable schemas in components/schemas — reduces duplication in generated types
3. Use tags to group operations — works with tags and tags-split modes
4. Define response types for all operations — enables full type safety
5. Mark required fields — affects optional/required in generated TypeScript interfaces
6. Use x-enumNames for numeric enums — generates readable const names
7. Provide example values — used by mock generation when useExamples: true
8. Use application/x-ndjson content type for streaming endpoints — enables typed NDJSON generation

CLI Reference

orval                                    # Generate using auto-discovered config
orval --config ./api/orval.config.ts     # Specify config file
orval --project petstore                 # Run specific project(s)
orval --watch                            # Watch mode
orval --watch ./src                      # Watch specific directory
orval --clean                            # Clean generated files
orval --prettier                         # Format with Prettier
orval --biome                            # Format with Biome
orval --tsconfig ./src/tsconfig.json     # Custom tsconfig path
orval --mode split                       # Override output mode
orval --client react-query               # Override client
orval --mock                             # Override mock generation
orval --input ./spec.yaml --output ./api.ts  # Direct generation

Resources

• Documentation
• GitHub
• Sample Projects