This content originally appeared on DEV Community and was authored by Locahl
http://localhost:3000 works. It also breaks a few real-world checks early:
- cookies scoped to a real-looking host
- absolute URLs in emails and webhooks
- multi-app setups (
app,api,admin) - OAuth redirect allowlists that hate bare localhost quirks
A local hostname like myapp.test is often cleaner.
1. Add the hostname
In /etc/hosts (macOS/Linux) or C:\Windows\System32\drivers\etc\hosts (Windows):
127.0.0.1 myapp.test
127.0.0.1 api.myapp.test
Prefer .test. It is reserved for testing. Avoid inventing fake .com names you might later need for real DNS.
Flush DNS after saving.
2. Point your app at it
Many stacks already bind 0.0.0.0 or 127.0.0.1. You only change the URL you open:
http://myapp.test:3000
If the framework reads HOST / APP_URL:
APP_URL=http://myapp.test:3000
Keep the port unless you put a reverse proxy in front.
3. Optional: drop the port with a proxy
Caddy example:
myapp.test {
reverse_proxy localhost:3000
}
Then open http://myapp.test. Same idea with nginx or Traefik.
4. HTTPS locally
Some features need secure cookies or HTTPS redirects.
Options:
- Caddy or mkcert for a local cert on
myapp.test - Your framework's built-in HTTPS in development
Do not fight browser warnings with a public domain pointed at 127.0.0.1 unless you control that name.
5. Frontend and API on sibling hosts
127.0.0.1 app.myapp.test
127.0.0.1 api.myapp.test
Frontend on :3000, API on :4000. CORS and cookie domains become closer to production:
Domain=.myapp.test
That is often the whole reason to stop using plain localhost.
Checklist when it "does not work"
- Hosts line exists and is not commented
- DNS cache flushed
- App is listening on the port you typed
- You opened
myapp.test, notlocalhost - Proxy config matches the hostname if you use one
Terminal check:
ping -c 1 myapp.test
# should show 127.0.0.1
When to skip this
Throwaway demos and single-file experiments are fine on localhost.
Reach for a custom local domain when cookies, redirects, or multiple services start fighting you. One hosts line usually ends the fight.
If you switch hosts a lot, a small desktop manager helps keep profiles and DNS flush in one place: Locahl.
This content originally appeared on DEV Community and was authored by Locahl
Locahl | Sciencx (2026-07-16T22:28:29+00:00) Use a custom local domain instead of localhost:3000. Retrieved from https://www.scien.cx/2026/07/16/use-a-custom-local-domain-instead-of-localhost3000/
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