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Sideplay

Free subdomain guide

A memorable address for the server you already run.

Sideplay connects a subdomain such as name.sideplay.dev or name.runvia.app to your own web server through a reverse proxy. It's free: every approved account gets two addresses, and you can ask for more once both are in use.

1. Sign in and get approved

Sign in with your GitHub account. During the beta every new account is reviewed by an operator before it can claim addresses or submit projects.

Once approved you can do everything from your workspace.

2. Choose a name and enter your server

Pick a name using 1–63 lowercase letters, numbers and hyphens. A hyphen can't be the first or last character. Existing service names and reserved words can't be claimed.

Enter a public IPv4/IPv6 address or a DNS hostname plus an allowed port. You host the server yourself — localhost, a laptop or a private IP can't be reached from the internet.

Before you submit

  • Your server is reachable from the public internet
  • It answers HTTP or HTTPS on the port you enter
  • Websites, REST APIs and WebSockets are all fine

3. Approval and deployment

Saving settings doesn't make the address live instantly. Each change goes through:

  1. Submitted
  2. Approved
  3. Deployed

Checking that your server actually responds is a separate step you can run from the workspace. Until a change is deployed, the previous working configuration stays in place.

Visitors always connect over HTTPS. If you choose an HTTP upstream, traffic between our proxy and your server is not encrypted, so prefer HTTPS when you can.

4. Add the Sideplay tag

Every subdomain must include the Sideplay tag (a single script line) in the main HTML of its service. Without it, operators may stop the subdomain on their own authority.

Each approved subdomain must add the Sideplay tag to its service's main HTML within a week. Copy the tag from the service card in your workspace or from the screen you see after applying.

Tag for this subdomain
<script
  src="https://sideplay.dev/sdk.js"
  data-project="(value from your workspace)"
  async
></script>

Where does it go?

Put it inside the <head> of the main HTML your subdomain serves at its first page (/). Nothing else needs to change.

HTML
Inside <head> in index.html
React · Vue (Vite, etc.)
Inside <head> in the project's root index.html
Next.js
As a plain <script> tag inside <head> in app/layout.tsx (not next/script)
Server templates
Inside <head> in the layout every page shares

Sideplay's server checks for the tag directly in the HTML of your first page (/), so it must be in the HTML from the start rather than injected later by JavaScript. Once it's in place it's picked up automatically, or press “Check now” to apply it right away.

Why is it required?

  • To stop people from grabbing subdomains they don't intend to use.
  • To confirm that a subdomain is actually serving something (a light health check).
  • To reclaim abandoned subdomains so other people can use those names.
  • To deliver operational notices from Sideplay, such as new features or service announcements.

What happens if it isn't found

  1. If the tag isn't seen within 7 days of approval, or hasn't been seen for more than 7 days, the subdomain is paused. A paused subdomain doesn't serve traffic.
  2. For 14 days after the expiry date you can request reactivation from your workspace. An operator reviews it and reopens the subdomain.
  3. After those 14 days the subdomain is stopped and its name is released. Anyone can claim it, and you'd need to apply again from scratch.

5. Share what you built

Add your project's name, a short description and URL from your workspace. After a quick review it appears in the gallery. You don't need a Sideplay address to share a project.

What's included

Sideplay connects web servers through a reverse proxy. We don't edit MX, TXT or SRV records, run mail servers, forward arbitrary TCP/UDP services or host your code.

See the community guidelines for the rules of the playground.

FAQ

Do I really have to add the Sideplay tag?

Yes. If the tag isn't found within a week of approval, or isn't seen for more than a week, the subdomain is paused. Without a reactivation request within 14 days, the name is released. The tag uses no cookies and only sends the page address and your project value.

Is it really free?

Yes. Every approved account gets its first two subdomains at no cost, beta or not. If that ever changes we'll announce it well in advance.

Can I get more than two addresses?

Yes. Once both of your addresses are in use, request a higher limit from your workspace and tell us why. An operator looks at the two services you already run and raises the limit if they're in good shape.

Can I change my subdomain's name later?

Names are fixed once claimed. To use a different name, request a new address and delete the old one.

How long does approval take?

Usually within a day. Operators review new accounts, new addresses and gallery submissions by hand.

What happens when I delete an address?

The routing is removed first. The name isn't handed to anyone else until removal is complete.

Claim your subdomain