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

# Authentication

> Authenticate your API requests with an API key

All API requests (except `/health`) require an API key passed via the `x-api-key` header.

## Getting your API key

1. Sign up at [companies.social](https://companies.social)
2. Go to the **Dashboard**
3. Create a new API key

Your key will be prefixed with `ck_` and shown once — store it securely.

## Using your API key

Include the key in every request:

```bash theme={null}
curl -H "x-api-key: ck_live_abc123..." \
  https://api.companies.social/domain/stripe.com
```

<Warning>
  Never expose your API key in client-side code. Always make API calls from your server.
</Warning>

## Error responses

| Status | Meaning                                               |
| ------ | ----------------------------------------------------- |
| `401`  | Missing or invalid API key                            |
| `401`  | No active subscription for this account               |
| `429`  | Rate limit exceeded — see [Rate Limits](/rate-limits) |