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

# Authentication

> Send your API key as a Bearer token. One key works across all four markets.

Every request to the Global Company Data API needs an `Authorization` header carrying your API key
as a Bearer token. There are no unauthenticated endpoints.

## Request format

```http theme={null}
Authorization: Bearer YOUR_API_KEY
```

A complete request:

```bash theme={null}
curl --request GET \
  --url "https://global-api.thedatacity.com/v1/us/filters" \
  --header "Authorization: Bearer YOUR_API_KEY"
```

## One key, four markets

The same key works for the United States, France, Germany and Ireland. You do not need a separate
key per market, and you do not need to tell us which markets you intend to call.

The market is chosen by the path segment after `/v1/`, not by the key.

<Note>
  Keys are not currently scoped to individual markets. Any valid key can reach all four. If you need
  a key restricted to a subset, tell us — it is not something you can configure yourself today.
</Note>

## Getting a key

API keys are issued by hand. Email [support@thedatacity.com](mailto:support@thedatacity.com) with:

* The name of your organisation.
* The email address of the person who will hold the key.
* Which markets you expect to use.

We provision the key and reply with the value.

<Warning>
  Treat your API key like a password. Do not commit it to source control, ship it in a browser
  bundle, or paste it into a shared chat. Store it in an environment variable or a secrets manager.
</Warning>

## Replacing a key

Email [support@thedatacity.com](mailto:support@thedatacity.com) to have a key revoked and reissued.
Revocation takes effect immediately, so arrange the swap before you ask us to revoke the old key.

## Authentication failures

A missing, malformed or revoked key returns `401`:

```json theme={null}
{
  "type": "https://httpproblems.com/http-status/401",
  "title": "Unauthorized",
  "status": 401,
  "detail": "No Authorization Header",
  "instance": "/v1/us/companies"
}
```

The `detail` field distinguishes a missing header from a rejected key. See
[Errors](/global-api/guides/errors) for the full response shape.

## AI assistants

The Model Context Protocol server for each market uses the same key and the same header. See
[Connect an AI assistant](/global-api/index) on the overview page.