# Developers

- [Environments](/docs/developers/environments.md): Understand Kizen API environments, including GO and FMO production instances, API base URLs, environment-specific authentication, and common environment mismatch errors.
- [Authentication](/docs/developers/authentication.md): The Kizen API supports multiple authentication methods.
- [Build with APIs](/docs/developers/building-with-apis.md): Explore the Kizen API — learn how it works, key concepts like Objects, Records, and Permissions, and the authentication methods needed to start building integrations.
- [Generate API Credentials](/docs/developers/building-with-apis/generating-api-credentials.md): Learn how to generate your Kizen API Key, User ID, and Business ID to authenticate API requests and connect external systems to your Kizen business account.
- [Create Your First API Call](/docs/developers/building-with-apis/creating-your-first-api-call.md): Learn how to make your first authenticated Kizen API call. This step-by-step guide walks developers through assembling credentials and calling the Kizen REST API.