# Axonaut > API REST for business management: CRM, invoicing, quotes, projects, HR, accounting. ## API Reference - [OpenAPI Spec (JSON)](https://axonaut.com/api/v2/doc.json): full OpenAPI 3.0 specification, auto-generated - [Swagger UI](https://axonaut.com/api/v2/doc): interactive interface to explore and test the API ## Authentication All requests must include the `userApiKey` header: ``` userApiKey: ``` ### Generate a key In the Axonaut interface: Settings (wrench icon) > API > 'API v2' tab > click 'Show your API key'. ## Base URL ``` https://axonaut.com ```