Theme Font & Size Changer

Name: Theme Font & Size Changer
Rating: 2.2054 (224 reviews)
Author: Baris Derin

Theme Font & Size Changer lets you change the global font size and font family used for the user interface in Firefox. Design your browser with your favorite font.

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Features & Capabilities

Theme Font & Size Changer is a versatile browser extension that allows Firefox users to customize the font size and font family globally within the browser's user interface—including menus, toolbars, and windows. Unlike typical text zoom on web pages, this tool modifies the interface fonts themselves, making it especially useful for visually impaired users or those utilizing high-resolution or wide-screen displays.

The extension supports instant application of font and size changes across sessions, offering options to adjust zoom, font style, weight, color, and background color of toolbars and context menus. It includes a convenient toolbar button and a Tools menu option for easy access to settings. Additionally, it supports Thunderbird and SeaMonkey, providing a consistent customization experience across multiple Mozilla-based applications. With accessibility and personal design in mind, Theme Font & Size Changer empowers users to tailor their browsing environment to their preferences and needs.

User Growth & Download Statistics

Add-on

By:

Daily users:

Rating:

Version:

62.1resigned1 Last updated: 2024-04-25

Version code:

5726050

Creation date:

2010-05-28

Risk:

Permissions:

tabs
storage
management
activeTab
downloads
contextMenus
<all_urls>
http://*/*
https://*/*
menus

Content scripts matches:

*.barisderin.com

Size:

233.92KB

Email:

su*****@barisderin.com

URLs:

Website

Full description:

Source:

Firefox Add-ons Store

Data ingested on:

2026-07-03

Compare stats and ranking:

Ranking

# 1,140 ▲ 12

Other rankings

#115 in Social & Communication

#178 in Appearance ▲ 2

#3 in font keyword 55

#3 in size keyword 11

#17 in exchange keyword 12

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For Developers

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Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.

Developed by:

Baris Derin

Firefox Add-ons Store

https://addons.mozilla.org/firefox/addon/theme-font-size-changer/

Email:

su*****@barisderin.com

Website:

http://barisderin.com/?p=287

User Reviews

Users trying to use Theme Font & Size Changer report that it is largely non-functional with recent Firefox versions, with key features missing or removed. The add-on appears abandoned, with no active development since 2014. While it has a simple interface featuring background and text color buttons, it fails to deliver on its main promise of adjusting font sizes, making it ineffective and frustrating for users.

Pros

Simple interface with a couple of color options (background color and text color).

Cons

The extension does not work with recent Firefox versions (e.g., v.139.0 and Quantum and later).
Most key functionalities described in documentation are missing or have been removed.
Extension appears abandoned and no longer maintained, with no updates since around 2014.
Users must manually install from file and encounter messages that it is mostly non-functional.

Recent reviews

Unfortunately this extension is dead on arrival. It is a shame because now I have to go dig into the css and do all that nonsense to increase the size of the font in the FF menu bar. Aye yi yi what a pain in the arse. Adjusting fonts should not even require leaving the FF UI. I don't know why Mozilla FF doesn't make a user friendly page to adjust fonts. It's just dumb. But this extension is not going to fix it cuz it's broke too :(

by Fi*****, 2025-07-31

by To*****, 2025-07-15

"It could be useful, but unfortunately, it doesn't work (at least not, with FF v.139.0)"

by Pe*****, 2025-05-27

View all user reviews ›

Is Theme Font & Size Changer Safe?

Risk impact

Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

Theme Font & Size Changer requires some sensitive permissions that could impact your browser and data security. Exercise caution before installing.

Risk impact analysis details

Critical Grants access to browser tabs, which can be used to track user browsing habits and history, presenting a privacy concern.
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Risk likelihood

Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

Theme Font & Size Changer is probably trust-worthy. Prefer other publishers if available. Exercise caution when installing this add-on.

Risk likelihood analysis details

High This extension has low user count. Unpopular extensions may not be stable or safe.
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