Extension source viewer

Name: Extension source viewer
Rating: 4.8739 (111 reviews)
Author: Rob W

By: Rob W

View source code of Firefox add-ons and Chrome extensions (crx/nex/xpi) from addons.mozilla.org, the Chrome Webstore and elsewhere, with CRX Viewer (crxviewer).

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Features & Capabilities

The Extension Source Viewer Chrome extension enables users to effortlessly view and download the source code of Firefox add-ons and Chrome extensions, including those for Opera, Edge, and Thunderbird. When detected, it adds a convenient button next to the address bar providing options to download the extension as a zip file or view its source directly.

The viewer tab offers advanced features such as syntax highlighting, automatic code beautification, regex-based file filtering and content search, image preview, and hash calculations for file integrity. Users can navigate search results easily, explore embedded zip files, and obtain permalinks within extension files. This versatile tool also facilitates downloading Chrome Web Store extensions for different platforms. Known as CRX Viewer or crxviewer, this extension enhances transparency and accessibility for developer and user communities.

User Growth & Download Statistics

Add-on Developer Tools Programming

By:

Rob W

Daily users:

1,565 -26

Rating:

4.87

(111)

Version:

1.7.0 Last updated: 2023-12-10

Version code:

5663065

Creation date:

2016-07-24

Risk:

Permissions:

Size:

241.70KB

Email:

ro*****@robwu.nl

URLs:

Website

Full description:

Source:

Firefox Add-ons Store

Data ingested on:

2026-06-18

Compare stats and ranking:

Ranking

# 2,533 ▼ 25

Other rankings

#288 in Web Development ▼ 2

#5 in source keyword 19

#10 in source code keyword 14

#15 in viewer keyword 56

#17 in resource keyword 28 ▼ 1

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Other platforms

Chrome extension source viewer (v1.7.0)

100,000 4.59

(435)

For Developers

Monetize with App Pass Boost with Extension Booster

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:

Rob W

Firefox Add-ons Store

https://addons.mozilla.org/firefox/addon/crxviewer/

Email:

ro*****@robwu.nl

Website:

https://github.com/Rob--W/crxviewer/issues

Permission Change History

2023-12-10: Version 1.6.12 → 1.7.0

Add Permissions: alarms cookies

User Reviews

Users praise Extension Source Viewer for enabling visibility into an add-on's code before installation, calling it handy and essential for security-conscious browsing. It generally works for downloaded addons, but several issues appear: the download as zip option sometimes fails; compatibility glitches (notably with Waterfox Classic) and occasional error messages when viewing code; and update problems that require reinstalling. Overall, it's valued as a safety tool despite these occasional drawbacks.

Pros

It lets you view the add-on's source code before install, boosting transparency.
Handy and practical for checking what an add-on does.
Works for downloaded add-ons and helps verify code before use.

Cons

The download as zip option can fail with a 'Failed' error.
Compatibility issues with some browsers (notably Waterfox Classic) and related UI problems.
Update/upgrade can require reinstalling the extension.

Recent reviews

Very useful, this is a pain to dig up otherwise. Works great, no issues with zip downloads here either.

by Ra*****, 2026-05-14

"Download as zip" doesn't work. I've tried many times on different add-ons but it always says "Failed" on download.

by Jo*****, 2026-03-29

by Se*****, 2025-11-16

View all user reviews ›

Is Extension source viewer 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.

Extension source viewer 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.
Critical ****** ****** ** *** ********* ****** * *********** ******** **** ** ** *** ******* *** ****** **** **** *** ******* *****
High ****** *** ********* ** ******* *** ******* ******* ** ****** *** *** ******** ******
Medium ****** ********** ** ******** ********** *** ********* ******* ******** ****** ******** ****** ********

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.

Extension source viewer has earned a fairly good reputation and likely can be trusted.

Risk likelihood analysis details

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