CORS Unblock

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

CORS Unblock - Eliminate CORS Errors in Firefox

"CORS Unblock" is a Firefox extension offering control over XMLHttpRequest and fetch methods. It appends custom 'access-control-allow-origin' and 'access-control-allow-methods' headers to every browser request, resolving CORS (Cross Origin Resource Sharing) errors. Its features include toggling on/off from the toolbar, customizing allowed methods, and options to not overwrite server-filled headers. Supports WEBDAV methods.

Add-on stats

By: Balvin
Daily users: 7,428
Rating: 3.93
(30)
Version: 0.3.8 (Last updated: 2024-02-11)
Creation date: 2019-01-22
Weekly download count: 352
Firefox on Android: No
Risk impact: High risk impact
Risk likelihood:
Manifest version: 2
Permissions:
  • storage
  • <all_urls>
  • webRequest
  • webRequestBlocking
  • declarativeNetRequest
  • contextMenus
Size: 211.30K
URLs: Website

Other platforms

CORS Unblock (v0.3.8)
4.17 (164) 200,000
Not available on Android
CORS Unblock (v0.3.8)
4.30 (12) 52,137
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Add-on summary

This extension provides control over XMLHttpRequest and fetch methods by providing custom "access-control-allow-origin" and "access-control-allow-methods" headers to every requests that the browser receives. A user can toggle the extension on and off from the toolbar button. To modify how these headers are altered, use the right-click context menu items. You can customize what method are allowed. The default option is to allow 'GET', 'PUT', 'POST', 'DELETE', 'HEAD', 'OPTIONS', 'PATCH' methods. You can also ask the extension not to overwrite these headers when the server already fills them.

Preview: https://www.youtube.com/watch?v=8berLeTjKDM

Default values: Access-Control-Allow-Origin: request initiator or '' Access-Control-Allow-Methods: 'GET, PUT, POST, DELETE, HEAD, OPTIONS, PATCH, PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, LOCK' Access-Control-Allow-Methods: request initiator or '' Access-Control-Allow-Credentials: 'true' Access-Control-Expose-Headers: request initiator or '*'

To report bugs please use: https://github.com/balvin-perrie/Access-Control-Allow-Origin---Unblock

Change Log:

See more

User reviews

These summaries are automatically generated weekly using AI based on recent user reviews. Firefox Browser Add-ons does not verify user reviews, so some user reviews may be inaccurate, spammy, or outdated.
Pros
  • Does what it's supposed to do
  • Useful for modifying "Access-Control-Expose-Headers"
  • Easy to enable/disable with a click
  • Works well for frontend development tasks
Cons
  • Does not work on multiple recent Firefox versions (e.g., FF 86, FF Developer 78)
  • Some users report that it causes issues with specific sites (e.g., YouTube)
  • Lack of whitelisting options for specific domains like localhost
Most mentioned
  • Extension stopped working as of September 2023
  • Whitelisting feature requested
  • Inconsistent functionality across different Firefox versions
User reviews
This extension does what it's supposed to do. Thanks. I don't keep it as I only used it for testing and you're not supposed to solve CORS issues like this.

by waldyrious, 2024-12-28

Does what it says on the tin, would be nice though to have the ability to whitelist sites, like just localhost, instead of all domains.
by Zach Bellay, 2024-11-05
View all user reviews

Add-on safety

Risk impact

CORS Unblock requires some sensitive permissions that could impact your browser and data security. 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.
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Risk likelihood

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.
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