Best Default Font Size Mozilla Addons Alternatives

Multi-line tab labels with custom font size. Infinite scroll for the tab bar. Custom tab widths for selected and unselected tabs. All features are optional and configurable in the toolbar panel.

Minimum Font Size Per Domain

This Add-On sets all form elements to 100% so elements where the font-size is not defined are not scaled by the text-scale-factor twice. This solves a wide spread problem on zoomed desktops.

Discussion: http://stackoverflow.com/questions/23783899

Assign Ctrl+Shift+0 (zero) (or Cmd+Shift+0 for Mac OS X) to set (or reset to default) the minimum font size for all font groups.
The value for the font size is specified in the add-on settings.

Simply makes address bar and its suggestions have bigger font. No annoying toggle button.
Based on Make Address Bar Font Size Bigger by Jonathan Marzullo.

Makes the whole internets grey with plain fonts.

Increases the font size of the URL/Address Bar.

I just used the package-add-on tool on Mozilla Dev Hub, and changed the CSS to increase the URL/Address Bar font-size (The source is viewable via a link below in the view information tab).

Increases the Thai font size on web pages so it's more easily readable.

Increases the Thai font size on web pages so it's more easily readable.

Makes the URL bar and Search bar more readable, and the navigation-toolbar compact.

Customize menus : Helps removing, moving and renaming menus and menu items
Colorize important menu for ease of use! (use Style (CSS))
Change or disable any of used keyboard shortcuts
Support: Firefox, Thunderbird and SeaMonkey

Removes color and background images, and/or the font settings, from the document.

Add buttons to change the font size on the toolbar.

Font Magnifier