# How do I authenticate?

> An X-Api-Key header, plus X-Project-Id to say which project you are acting in.

Source: https://warmerly.com/docs/faq/how-do-i-authenticate

An `X-Api-Key` header, plus `X-Project-Id` to say which project you are acting in.

## More from Frequently asked questions

- [Which plan has API access?](https://warmerly.com/docs/faq/which-plan-has-api-access): Agency.
- [Are there rate limits?](https://warmerly.com/docs/faq/are-there-rate-limits): Yes, per endpoint group, and they are separate from your plan's monthly allowances.
- [Can I get notified instead of polling?](https://warmerly.com/docs/faq/can-i-get-notified-instead-of-polling): Yes - subscribe to outbound webhooks for mailbox health events.