> ## Documentation Index
> Fetch the complete documentation index at: https://docs.circuit.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

> Obtain and use a bearer token with the Circuit Integration API.

The Integration API accepts a passkey-signed Circuit permit as a bearer token. It does not use a separate API key or signing secret.

### Get a token

Sign in with the Circuit CLI, then print the active token:

```bash theme={null}
circuit auth login
TOKEN=$(circuit auth token)
```

`circuit auth login` opens Circuit in your browser for passkey authentication. `circuit auth token` prints the resulting bearer token. See [CLI authentication](../../agent-developers/cli-references/authentication) for environment selection, token inspection, and headless use.

### Send the token

Pass the token in the `Authorization` header:

```bash theme={null}
curl "https://api.circuit.org/v1/user/info" \
  -H "Authorization: Bearer $TOKEN"
```

The token acts with the signed-in user's granted capabilities until it expires or is revoked. Treat it as a secret.

### Integration constraint

Circuit does not provide an embeddable end-user authentication widget. Token capture through the CLI supports trusted server-side and operator-managed integrations; it is not an in-app sign-in flow. Do not ship bearer tokens in browser bundles or ask users to enter them into an untrusted client.