Install on Android

Until Text Size Adjuster is on Firefox Add-ons, Firefox for Android needs a hidden option turned on once before it can install it. It takes a minute.

1. Download Text Size Adjuster on your phone. The file is signed by Mozilla.
2. In Firefox, open Settings → About Firefox and tap the Firefox logo five times, until it says the debug menu is enabled.
3. Go back to Settings. Near the bottom, under Advanced, tap Install add-on from file and choose the file you downloaded.
4. Tap Add when Firefox asks.

You need Firefox for Android 142 or newer. Firefox asks for permission to access your data for all websites. Text Size Adjuster needs that to resize the text on the pages you visit, and collects nothing.

Then visit any page: zoom in and the control appears. Your chosen size is remembered for each site, the same as on a computer. See how to use it.

From version 1.4.0 on, Firefox keeps it up to date: it checks for new versions and installs them itself. Earlier versions (1.1.0) don't update; if you have one, install it once more from the link above to get updates from then on. To see your version, open the add-on's Options.

For testers

Regular Firefox for Android only installs signed add-ons. Firefox Nightly for Android can also install the unsigned build, after setting xpinstall.signatures.required to false in about:config.