# API reference

See [Authorization](https://docs.cryptonly.net/api-reference/authorization.md) for API key authentication.

The [OpenAPI reference](/api-reference/openapi/) is the canonical schema for request and response fields.

## Related pages

- [Authorization](https://docs.cryptonly.net/api-reference/authorization.md): API keys for server-to-server requests
- [OpenAPI reference](https://docs.cryptonly.net/api-reference/openapi/): Request and response schema
- [Webhooks](https://docs.cryptonly.net/api-reference/webhooks.md): Payment notifications sent to your server
- [Invoices](https://docs.cryptonly.net/guides/invoices.md): Create a checkout payment