Advanced: install the extension manually

For technical users: ways to install an unsigned build of the extension, for testing. Most people should use the normal install, which installs the version signed by Mozilla.

The unsigned file is the current build, packaged but not signed by Mozilla. Building it yourself is described in the contributor section.

Both need Firefox 140 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.

1. Temporary load (quickest, for trying it out)

1. Open about:debugging#/runtime/this-firefox.
2. Click Load Temporary Add-on… and pick the downloaded unsigned .xpi.

Everything works, but Firefox removes it when it closes, so you repeat this each session.

2. Unsigned (Firefox Developer Edition, Nightly or ESR only)

These Firefox editions can be told to accept unsigned extensions; regular Firefox ignores this setting.

1. Open about:config and set xpinstall.signatures.required to false.
2. Download the unsigned .xpi.
3. Open about:addons, click the gear icon, choose Install Add-on From File…, and pick the .xpi. (Dragging the file onto a Firefox window also works.)

After installing

Visit any page. The on-page −/+ control appears, and the extension's toolbar button gives you another way to adjust the size. Come back to that site later — your chosen size is already applied.

Prefer not to deal with any of this? The userscript needs no signing at all; it just doesn't remember a size per site.