# API keys

**You don't need a key today.** Facts are free and keyless, and decisions are free during early access. Just call the [REST API](https://kaicast.com/developers/rest) or connect the [MCP server](https://kaicast.com/developers/mcp).

## When keys arrive

Keys come with metering for the decision layer. When they do:

- One key will work for **both** the REST API and the MCP server.
- Send it as `Authorization: Bearer kc_live_…` or `X-KaiCast-Key: kc_live_…` — never in a URL. `kc_test_…` keys will be for testing and never billed.
- Facts stay free and keyless.
- Registered developers get notice before anything changes, and sign-up will be plain HTTP so an agent can complete it with one human step (reading an emailed code).

Both endpoints already accept and ignore those headers, so you can wire the header in now without breaking anything.

## Get notified

Email [dawson@kaicast.com](mailto:dawson@kaicast.com) with what you're building. Volume, partnerships and new regions go to the same address.