You open the login page for one part of a website, and the password box dumps every account you ever saved on that whole site. Wrong usernames, wrong passwords, all piled together. Run a few sub-sites under one name and you see it daily.
A subdomain is the prefix part, like the "mail" or "vpn" in mail.example.com, and built-in password managers don't treat those as separate sites. A saved login filed under the main name gets offered across the whole site. One reader on the Brave forum put it flatly. No Chromium browser fills passwords per subdomain. Yeah, that bad.
Why browsers merge them
Many large sites share one login across their sub-sites. A bank might use login.bank.com and accounts.bank.com with the same password, so the browser bundles them and you don't save it twice. Handy.
Browsers file the password under the registrable domain, the main name you'd buy from a registrar, like example.com, and any mail or admin prefix in front rides along in the same bucket. But if your sub-sites use different logins, the browser crams them into one dropdown you can't sort out.
The Firefox fix
Firefox is the one mainstream browser with a built-in switch for this. Open the hidden config page by typing about followed by config in the address bar, accept the risk warning, then search for signon.includeOtherSubdomainsInLookup. Double-click it to flip true to false and restart Firefox.
Now the autofill box on a mail subdomain only shows logins you saved there. Your other logins aren't gone. They still sit in your saved-password list, out of the dropdown. Thirty seconds, done.
Mozilla Support thread on subdomain logins
Chrome, Edge, and Safari are stuck
Chrome and Edge both run on Chromium, and their built-in managers group subdomain logins together with no user-facing way to split them. No hidden flag, no settings switch I could find. Users have asked Chromium for better subdomain handling for years and it still isn't there. Brave runs on Chromium too, so it inherits the same thing.
Safari is the same story. Apple's AutoFill suggests saved logins from related sub-sites, with no setting to force an exact-subdomain match. None of the three browsers ships a switch like Firefox's.
Brave Community on per-subdomain logins
What to do without Firefox
The real fix on Chrome, Edge, or Safari is to drop the browser's keeper for a standalone one. Bitwarden and 1Password both let you tie a login to one exact host. But watch for one trap. By default, Bitwarden uses "base domain" matching, which still pools logins across subdomains, so you change it yourself. Not every manager makes this easy. Proton Pass lists URL matching on its 2026 roadmap but hasn't shipped it, so check before you trust it to split subdomains. The setup runs in four steps:
- Install the password manager's browser add-on.
- Turn off the browser's built-in password saving in its settings.
- Export your saved passwords from the browser, then import them into the new manager.
- For any login where the subdomain matters, switch its match type from base domain to "host," so it fills on that one exact host.
A little setup work, and your dropdown stops being garbage.
Where this leaves you
For a casual user this costs nothing, but anyone juggling ten or fifty sub-sites with separate logins feels it daily. Firefox users fix it in under a minute. Everyone else lives with the mess or sets host matching by hand in a password manager. Google, Microsoft, and Apple still don't expose a built-in switch for it.
