# Blueink API v2
# Overview
This document contains the detailed specification for version 2 of the Blueink eSignature API.
If just starting with the Blueink API, you might want to checkout the How-to Guides
and Guides that supplement this API specification.
> **Try it sends live requests**
>
>
> The interactive **Try it** panel sends real requests to the production API
> (`https://api.blueink.com`). Requests can create billable, legally-binding
> signature records and send real emails to signers. Use a test or restricted
> API key, and never run mutating endpoints unless you intend the side effects.
>
## Authentication
#### API Key
Authenticated requests require an `Authorization` header with the value `Token `. Example: `Authorization: Token abcd1234`.