Installing Every* Firefox Extension

Installing every* Firefox extension

Oh, you use Firefox? Name every extension.

Technically, this project managed to install 99.94% of all Firefox extensions. It turns out there are only about 84,000 extensions, which is small enough to fit into less than 50 gigabytes.

Scraping every Firefox extension

There’s a public API for the add-ons store with no authentication required. However, the search API only provides 600 pages, limiting visibility to 30,000 extensions.

To bypass this, the author used different sorting methods (created, rating, hotness) and eventually discovered that using exclude_addons or filtering by category in parallel allowed for a near-complete scrape. The final dataset was uploaded to Hugging Face for public analysis.

Analyzing the data

Biggest extensions

The largest extension is dmitlichess at 196.3 MB, packed with over 2,000 audio files. Other massive extensions include:

• (Unofficial) ReactBot Web (184.9 MB): Contains an entire Unity application.
• Eric’s Thumbnail Seasoning! (146.6 MB): A fork of YouTube MrBeastify with 900 .png files.
• YouTube OCR (128.3 MB): Uses Tesseract.js for text recognition.

The smallest extension, theTabs-saver, is only 7,518 bytes and contains no code.

Permissions and Developers

FalscheLaden takes the lead for the most permissions requested, asking for a staggering 3,695 permissions despite having zero users. In terms of volume, a developer named Dr. B is the most prolific, with 84 extensions, most of which appear to be AI-generated "slop" without icons or screenshots.

The Dark Side: Phishing and PUAs

Phishing

The dataset revealed several homoglyph attacks targeting crypto wallets. These extensions use look-alike characters to mimic legitimate wallets, then pop up forms asking for seed phrases. Some even used NocoDB spreadsheets to manage their phishing URLs.

SEO Spam

Many AI-generated extensions from 2025 were found to be simple shells used for SEO backlinking, despite Firefox using nofollow tags on homepage links for years.

Potentially Unwanted Applications (PUAs)

A massive pattern of "Custom Web Search" extensions was identified, totaling over 700,000 users. These extensions, such as Maps Assist or Package Tracking Tab, all reference "Innover Online Group Ltd" and serve to hijack the user's search engine for profit.

This deep dive into the Firefox ecosystem highlights that while the platform is robust, users must remain vigilant against bloatware, SEO schemes, and sophisticated phishing attempts.