CORS Unblock

Name: CORS Unblock
Rating: 3.7429 (35 reviews)
Author: Balvin

By: Balvin

No more CORS error by appending 'Access-Control-Allow-Origin: *' header to local and remote web requests when enabled

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Features & Capabilities

CORS Unblock is a powerful Chrome extension designed to eliminate Cross-Origin Resource Sharing (CORS) errors by appending custom Access-Control-Allow-Origin and related headers to all browser requests. Users can easily toggle the extension on or off from the toolbar and customize allowed HTTP methods such as GET, PUT, POST, DELETE, and more through the context menu.

It supports a wide range of HTTP methods including WEBDAV-specific ones and provides configurable options to respect existing server headers or overwrite them. This extension is ideal for developers and testers working with cross-origin APIs or web services who need seamless control over CORS policies without server-side changes. Comprehensive documentation and bug reporting are available on its GitHub repository.

User Growth & Download Statistics

Add-on Developer Tools Programming

By:

Balvin

Daily users:

6,737 139

Rating:

3.74

(35)

Version:

0.3.8 Last updated: 2024-02-11

Version code:

5690645

Creation date:

2019-01-22

Risk:

Permissions:

Size:

206.35KB

URLs:

Website

Full description:

Source:

Firefox Add-ons Store

Data ingested on:

2026-06-19

Compare stats and ranking:

Ranking

# 971 ▲ 14

Other rankings

#95 in Web Development ▲ 2

#207 in Privacy & Security ▲ 1

#10 in unblock keyword 42

#30 in block ads keyword 96

#30 in writer's block keyword 12

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Other platforms

CORS Unblock (v0.5.2)

200,000 4.07

(174)

CORS Unblock (v0.5.2)

53,646 3.90

(14)

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:

Balvin

Firefox Add-ons Store

https://addons.mozilla.org/firefox/addon/cors-unblock/

Website:

https://add0n.com/access-control.html

Permission Change History

2024-02-11: Version 0.1.9 → 0.3.8

Add Permissions: declarativeNetRequest

User Reviews

Users generally praise CORS Unblock when it works, noting it does what it promises and can be a real time-saver for developers, with features like adjusting Access-Control-Expose-Headers. However, many reviews report reliability problems, with CORS requests still failing on numerous sites, and occasional breaks on services like YouTube. Some compatibility issues appear across Firefox versions (e.g., Firefox 86) or after updates. A common request is to add site whitelisting to limit the extension's effect to specific domains.

Pros

Works as intended when enabled; users report it turning on properly via the extension icon and it functioning well.
Useful for testing and development; can save time for frontend work.
Allows modifying Access-Control-Expose-Headers, a handy feature.
Widely considered a needed and valuable CORS extension for Firefox when it works.

Cons

Unreliable or non-functional on many sites; reports of requests still failing.
Can cause issues on some sites (e.g., breaks YouTube playback) and other compatibility problems.
Lacks site whitelisting; users request the ability to restrict the extension to specific domains.
Compatibility and timing issues across Firefox versions (e.g., reported problems around Firefox 86 and Sept 2023).

Recent reviews

by Fi*****, 2025-11-10

amazing and fantastic extension. for those who find it not working properly: once you're on the website you want to unlock cors for, CLICK THE EXTENSION ICON in the list, so the letter "C" on it's icon BECOMES YELLOW. that means you turned it on: works AMAZINGLY, best extension ever.

by ra*****, 2025-08-03

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

View all user reviews ›

Is CORS Unblock 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.

CORS Unblock requires a few sensitive permissions. Exercise caution before installing.

Risk impact analysis details

Critical Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
High ****** *** ********* ** ******* *** ******* ******* ** ****** *** *** ******** ******

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.

CORS Unblock 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 **** ********* *** **** **** *******