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

# Architecture

> How requests are routed and how the newsletter is resolved from the API key.

Requests are sent to a single centralized API path, and the newsletter context is resolved
from the API key itself — you never pass a newsletter ID.

<Card title="Base URL">
  ```
  https://app.letterbucket.com/api/v1/
  ```
</Card>

## Request flow

```
Client
  ↓
https://app.letterbucket.com/api/v1/
  ↓
Authorization: Bearer sk_xxxxx
  ↓
API validates the key, capabilities, throttling and payload
  ↓
Newsletter is resolved from the API key
  ↓
Subscriber operation
  ↓
Standard JSON response
```

<Warning>
  Do not publish permanent production API keys. For demo usage, prefer short-lived sandbox keys
  with low limits and periodic data cleanup.
</Warning>