@untools/sdkgen

Generate TypeScript SDKs, Python SDKs, and vanilla fetch clients from an OpenAPI spec — local file or URL.

Inspired by Fern. No cloud required, no config files, just point it at a spec.

Install

# Install globally
npm install -g @untools/sdkgen

# Or run directly via npx
npx @untools/sdkgen <input> [options]

Usage

sdkgen <input> [options]

Arguments

• <input>: Path to an OpenAPI JSON/YAML file, or a URL to an OpenAPI endpoint (e.g., https://api.example.com/openapi.json).

Options

• -o, --output <dir>: Output directory (default: ./generated).
• -l, --lang <langs>: Comma-separated list of targets: typescript, python, fetch (default: typescript,python,fetch).
• -n, --name <name>: Package name (default: derived from spec title).
• -h, --help: Show help message.

Examples

# Generate all three targets from a local file
sdkgen ./openapi.json

# TypeScript + Python from a live URL
sdkgen https://api.example.com/openapi.json -l typescript,python

# Just fetch wrappers with a custom output directory and package name
sdkgen ./spec.yaml -l fetch -o ./sdk -n my-api

Output Structure

The tool generates a clean, modular structure for each language:

generated/
├── typescript/
│   ├── src/
│   │   ├── types.ts          ← All schema interfaces (namespaced)
│   │   ├── errors.ts         ← APIError class
│   │   ├── <tag>.ts          ← Typed client classes per OpenAPI tag
│   │   └── index.ts          ← Composite SDK entry point
│   ├── package.json
│   └── tsconfig.json
│
├── python/
│   ├── <pkg>/
│   │   ├── __init__.py       ← Composite SDK class
│   │   ├── models.py         ← @dataclass models
│   │   ├── exceptions.py     ← APIError
│   │   └── <tag>.py          ← Client classes per tag
│   ├── setup.py
│   └── requirements.txt
│
└── fetch/
    ├── config.js             ← createConfig() helper
    ├── <tag>.js              ← Async functions per tag
    ├── index.js              ← Factory entry point
    └── package.json

Key Features

TypeScript SDK

• Full Type Safety: Generates interfaces for all schemas with proper namespacing.
• Tag-based Clients: Groups operations by OpenAPI tags for a clean API.
• JSDoc Support: Pulls summary and description from the spec into your IDE.
• Modern Fetch: Uses vanilla fetch with no heavy dependencies.

Python SDK

• Type Hinting: Full support for Python type hints.
• Data Classes: Uses @dataclass for all models.
• Requests-based: Reliable synchronous clients using the requests library.

Fetch Clients

• Zero Dependency: Lightweight JavaScript wrappers for quick integrations.
• Modular: Only use what you need.

Development

# Clone the repository
git clone https://github.com/aevrHQ/untools-sdkgen.git
cd untools-sdkgen/sdkgen

# Install dependencies
npm install

# Build the project
npm run build

# Link for local testing
npm link

Releasing

This project uses standard-version for automated versioning and changelog generation.

npm run release        # Standard patch release
npm run release:minor  # Minor feature release
npm run release:major  # Major breaking release

License

MIT