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

# Authentication

> How to authenticate with the LeadTrackr API

Most API endpoints require authentication via an **API key** sent in the `X-API-Key` header.

## Getting your API key

1. Go to your [LeadTrackr Dashboard](https://app.leadtrackr.io)
2. Open the project you want to connect
3. Navigate to **Settings** and click **API Integration** in the sidebar
4. Copy the **API Key**

## Using your API key

Include the API key in the `X-API-Key` header with every request:

```bash theme={null}
curl -X GET https://app.leadtrackr.io/api/leads/getLeads \
  -H "X-API-Key: your-api-key-here"
```

## Endpoints without authentication

The [Create Lead](/api-reference/leads/create-lead) endpoint does **not** require an API key. It is designed for client-side use (e.g. from Google Tag Manager or browser scripts) and identifies the project via the `projectId` field in the request body.

## Error responses

If the API key is missing or invalid, you will receive a `401` response:

```json theme={null}
{
  "message": "Missing X-API-Key header"
}
```

```json theme={null}
{
  "message": "Invalid API key"
}
```