Have you ever wondered how to enable users to create their own subdomain? For example slack workspaces (space.slack.com) or hashnode blogs (name.hashnode.dev).
Well, Vercel makes it very easy since they have support for wildcard domains.

What are Wildcard Domains?

You can think of a wildcard domain as a catch-all for subdomains.
If I go to foo.domain.com it will go to the same page as bar.domain.com.
Then on the client side, you can serve different content for different subdomains. This will make more sense later.

Setting one up on Vercel is super easy and it has built-in HTTPS.

Adding Wildcard Domains

First, you need to have a domain available. You can buy one from any domain registrar like namecheap or porkbun.
For this example, I'll use shopeetracker.com. It's a throwaway domain that I don't use anymore.

Next, go to your projects Domains tab, enter a wildcard domain, and follow the instructions stated. For example, my domain is shopeetracker.com and I got it from Namecheap.
Then I'll input *.shopeetracker.com and configure my nameservers.

Once you have done that you're all set! Pretty easy right?

Detecting the subdomain

Detecting the subdomain happens at the client-side since we don't have access to the window object on the server-side.
Using a simple helper function we can extract the subdomain from the URL.

export const getPageData = async () => {
  const { host } = window.location;
  const splitHost = host.split('.');
  const isDev = host.includes('localhost');

  if (splitHost.length === 3 || (isDev && splitHost.length === 2)) {
    // This is your the subdomain
    // Ex. if foo.domain.com then page === 'foo'
    const page = splitHost[0];
    if (page === 'www') {
      return null;
    }

    // You can do your fetching logic here for each subdomain

    return page;
  }

  return null;
};

Demo

A running example can be found on https://shopeetracker.com, and the source code is available in a Github Repo.

Conclusion

Providing custom subdomains can make users feel special. And with wildcard domains, it can be done quickly.
If you tried this out in any of your projects hit me up on Twitter.
I also have a newsletter.

Resources

• Github Repo
• Live Website
• Vercel's Blog Post