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

# Bearer Token

> API Authentication

Use bearer token authentication when your integration sends requests from a single thanks.io account that you control. This is the simplest authentication method and the best starting point for most direct API integrations.

If you are building a multi-account SaaS integration where each customer connects their own thanks.io account, use [OAuth](/authentication/oauth) instead.

# API Key

All API requests must be authenticated with a bearer token. This token can be created in your [API Settings](https://dashboard.thanks.io/profile/api) under the "Personal Access Tokens (API Key)" section.

# Bearer Token

Once you have created a token, you can use it to authenticate your API requests by including it in the `Authorization` header as follows:

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

# Best For

* Internal tools and back-office automation
* Server-to-server integrations
* Your first API prototype or production integration for a single thanks.io account

# Example Request

Here is a minimal example of an authenticated request using `curl`:

```bash theme={null}
curl -X POST "https://api.thanks.io/api/v2/send/postcard" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "recipients": [{ 
      "name": "John Doe", 
      "address": "123 Main Street, Any Town, NY 12345"
    }],
    "message": "Hi %FIRST_NAME% - Thank you for your business!",
    "front_image_url": "https://d2md0c8rpvzmz5.cloudfront.net/inspiration_templates/default10.png"
  }'
```

For a full first-request walkthrough, including testing mode, see the [Quickstart](/quickstart).