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

# Resend

> Send email alerts when services go down or for custom notifications.

# Resend

Resend is used for sending email alerts, primarily for health check failures (services going down or degraded). It also supports custom alert emails.

## What it powers

* **Alert system** -- Sends formatted HTML emails when BetterStack reports services as DOWN or DEGRADED
* **Custom alerts** -- Send arbitrary alert emails via the `/api/alerts/send` endpoint

## Getting your API key

<Steps>
  <Step title="Sign in to Resend">
    Go to [resend.com](https://resend.com/) and sign in.
  </Step>

  <Step title="Create an API key">
    Go to **API Keys** in the sidebar (or visit [resend.com/api-keys](https://resend.com/api-keys)).

    Click **Create API Key**. Give it a name and select appropriate permissions.
  </Step>

  <Step title="Verify a domain or use the test address">
    Go to **Domains** and add/verify a sending domain.

    Alternatively, for testing, you can use the `onboarding@resend.dev` sender address.
  </Step>
</Steps>

## Environment variables

```bash .env.local theme={null}
RESEND_API_KEY=re_xxxxxxxxxxxxxxxxxxxxxxxxxxxx
RESEND_FROM_EMAIL=alerts@yourdomain.com
RESEND_TO_EMAIL=you@example.com
```

## API details

| Property       | Value                                         |
| -------------- | --------------------------------------------- |
| API base URL   | `https://api.resend.com`                      |
| Rate limit     | 2 req/s (free tier), 100/s (pro)              |
| Cache TTL      | N/A (send-only)                               |
| Authentication | Bearer token (`Authorization: Bearer re_...`) |

<Note>
  Resend is the only service that *sends* data out rather than fetching it in. If not configured, alerts simply won't be sent -- the dashboard still works normally.
</Note>