Which TLD to Use for Local Development (.test vs .localhost)

Use .test for local development. It is officially reserved by the IETF (RFC 6761) for testing, so it will never become a real public domain and cannot collide with a live site. Avoid .dev (a real Google-owned TLD that forces HTTPS) and .local (reserved for mDNS/Bonjour). The other safe reserved options are .localhost and .example.

Best TLDs for local development

Why .test wins

.test is guaranteed never to resolve on the public internet, so myapp.test always means "my local project." There is no risk that a colleague's typo leaks to a real site, and no browser HTTPS coercion.

Why avoid .dev and .app

Both are real TLDs on the HSTS preload list. Browsers force HTTPS on them, so a plain HTTP dev server at myapp.dev fails to load. If you need HTTPS locally, set it up deliberately with mkcert, see local HTTPS with mkcert.

Why avoid .local

.local is reserved for multicast DNS (Bonjour/Avahi). Using it for hosts entries causes slow lookups, intermittent failures, and conflicts with device discovery.

How to set up a .test domain

Add it to the hosts file and flush DNS:

127.0.0.1 myapp.test api.myapp.test

See the hosts file syntax guide and, when done, flush DNS. For many dynamic subdomains (*.myapp.test), the hosts file cannot use wildcards, use dnsmasq, covered in wildcard local domains with dnsmasq.

Manage them without editing files by hand

Juggling several .test domains across projects gets messy fast. ToggleHosts stores each mapping with a one-click toggle and flushes DNS automatically, so switching between projects is instant.

_Last reviewed: June 2026._

Sources and further reading

• RFC 6761, Special-Use Domain Names (IETF)
• HSTS preload list
• hosts(5) manual page (man7.org)