> **Building with AI coding agents?** Install the authstack plugin with one command. This equips your agent with accurate Scalekit implementation patterns.
>
> **Recommended**:
> ```bash
> npx @scalekit-inc/cli setup
> ```
>
> Global:
> ```bash
> npm install -g @scalekit-inc/cli
> scalekit setup
> ```
>
> Supports Claude Code, Cursor, GitHub Copilot, Codex + skills for 40+ agents.
> Features: full-stack-auth, agent-auth, mcp-auth, modular-sso, modular-scim.
> [Full setup guide](https://docs.scalekit.com/dev-kit/build-with-ai/)

---

# Add a custom domain on development

Development environments use the assigned Scalekit URL. Custom domains require Production and Customization Pro.
A Development environment cannot use a branded custom domain. **Configure Custom Domain** stays disabled, with the hint: custom domains are available on **Production** after you upgrade to the **Customization Pro** add-on.

Use the assigned Development environment URL for local work. When you need `auth.yourapp.com`, switch to Production and follow [Branded custom domains](/guides/custom-domain/).

## Before you start

- You can open the environment (**Development** or **Production**) from the header switcher
- For a branded hostname, you can edit DNS for a domain you own
- Customization Pro is billed at **$99/month** and includes custom domains, watermark removal, custom email provider, and custom email templates

> note: Development keeps the Scalekit hostname
>
> Each Development environment has a URL such as `yourenv-dev.scalekit.cloud`. Point local redirect URLs at that host. Do not create a production CNAME against a Development environment.

1. ## Open the Development environment

   In the header, click the **environment name** (right of the workspace name).

   Choose the Development environment you use for local work.

2. ## Open Custom Domain

   In the left nav, under **Customize**, click **Custom Domain**.

   The page shows **Custom Domain Add-on**, the **Environment URL**, and a **Live** badge.

3. ## Copy the Development environment URL

   Copy the **Environment URL** (for example `scalekit-xxxxx-dev.scalekit.cloud`).

   Use that host in Development redirect URLs, SDK `environmentUrl`, and local tests. See [Manage environments](/how-to/environments/).

   **Configure Custom Domain** is disabled on Development. Hover it to read the Production + Customization Pro requirement.

4. ## Configure a branded domain on Production

   Switch the header to a **Production** environment.

   Open **Customize > Custom Domain** and click **Configure Custom Domain**.

   If Customization Pro is not on this environment, Scalekit opens the **Customization Pro Add-on $99/month** dialog. Click **Upgrade**, then continue with the CNAME steps in [Branded custom domains](/guides/custom-domain/).

## Verify

**Development**

1. Open the **Environment URL** in a browser
2. Confirm the hosted login or admin page loads over HTTPS
3. Confirm Development redirect URLs use that host, not a production hostname

**Production (after upgrade)**

1. **Configure Custom Domain** is enabled
2. DNS verifies and the branded host serves HTTPS
3. Production redirect URLs use the branded host

> tip: Keep Development redirects on the Scalekit host
>
> After you brand Production, leave Development on `*.scalekit.cloud`. Sharing one hostname across Development and Production collides cookies and redirect URLs.

## Common questions

## Can I attach auth.dev.yourapp.com to Development?

Not through **Custom Domain**. That page only enables CNAME on Production with Customization Pro. Keep Development on the assigned `*-dev.scalekit.cloud` URL.

## Can I reuse the production hostname in Development?

No. Use the Development environment URL so cookies and redirect URLs never collide with Production.


---

## More Scalekit documentation

| Resource | What it contains | When to use it |
|----------|-----------------|----------------|
| [/llms.txt](/llms.txt) | Structured index with routing hints per product area | Start here — find which documentation set covers your topic before loading full content |
| [/llms-full.txt](/llms-full.txt) | Complete documentation for all Scalekit products in one file | Use when you need exhaustive context across multiple products or when the topic spans several areas |
| [sitemap-0.xml](https://docs.scalekit.com/sitemap-0.xml) | Full URL list of every documentation page | Use to discover specific page URLs you can fetch for targeted, page-level answers |