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

# Local development

> Set up a safe local workflow for testing MailChannels Email API sends, webhooks, and secrets.

Use a local workflow that exercises the real API without exposing secrets or surprising real recipients.

## Environment variables

Store credentials outside source control:

```bash theme={null}
MAILCHANNELS_API_KEY=xxx
```

Add `.env` to `.gitignore` and commit a `.env.example` with placeholder values only.

## Test sending

Start with one recipient you control. Use a subject prefix such as `[dev]` or `[staging]` so test mail is easy to identify.

Before sending a new template, use the `dry-run` option to render the message without sending it.

## Local webhook testing

During development:

1. Run your webhook receiver locally.
2. Expose it through a temporary HTTPS tunnel.
3. Register the tunnel URL as your webhook endpoint.
4. Run webhook validation.
5. Store the raw test event and verify signature validation before adding business logic.

## Avoid common mistakes

* Do not put API keys in browser JavaScript.
* Do not commit `.env` files, webhook signing keys, or private DKIM keys.
* Do not test with large recipient lists.
* Do not use production customer addresses for template experiments.
* Do not assume a successful API response means inbox placement. Use webhooks and mailbox checks.