u/Vintspect_48

It’s a miracle. I figured out how to install Firefox-specific extensions in Brave.

After successfully testing the installation of an MV2 Manifest extension in the latest version of Brave (Chromium 150), I happened to try installing extensions from the Firefox Add-ons store and, miraculously, I was able to install several extensions (.xpi) that are supposed to be installable only on Gecko-based browsers or Firefox. I still can’t believe this is possible. Here are the steps I followed:

1. Install the Chrome extension Source Viewer
2. Visit the Firefox add-ons website. For example, I tried installing Redirector and Volume Master).
3. Click on the Chrome extension source viewer and click “Download as ZIP.”
4. Similar to the MV2 extension guide, I extracted the ZIP file, opened the extensions page, and clicked “Load Unpacked.”
5. Both extensions were successfully installed in Brave, and after testing, they were active and worked just as they do in Firefox.

This method doesn’t always work, as some Firefox extensions—such as FoxyTab and Request Control—cannot be installed. So far, I’ve successfully installed Redirector, Volume Master, ClearURL, and LocalCDN directly from the Firefox add-ons page. Although ClearURL, LocalCDN, and Redirector have released Chrome extension versions (.crx), as far as I can tell, Volume Master has never released a Chrome (.crx) version. This might be a bug in the MV2 settings from yesterday, but I’m really happy to have found this workaround because I was able to get ClearURL and LocalCDN without the restrictions of the Chrome Web Store. Although some of these extensions show error messages on their extension pages, so far they’ve been working just fine.

That’s my brief experience—it was quite surprising and seemed almost impossible. I’ve successfully managed to install all Firefox-specific extensions on Brave. I hope this information is helpful.

The Developer Offline Mode (DOM) method is the result of extensive research across various Reddit forums and my own experiments, which have successfully installed MV2 manifest extensions in Brave browser version 1.92.134 (note: the Brave 1.92.134 update has disabled MV2 extensions, just like Google Chrome and other Chromium-based browsers, except for Brave’s four internal MV2 hosts). Since Brave uses the same engine as Google Chrome, I believe the DOM method can be applied to Google Chrome and other Chromium-based browsers running version 150 or later. Here are the steps:

A. Procedure

1. Close your browser and unpin it from the Windows taskbar before proceeding to the next step. This is to prevent conflicts.
2. Locate your browser’s shortcut by clicking the Windows icon > search for your browser’s name > “Open file location,” or navigate to the directory in File Explorer as follows: C:\Users\PC Name\AppData\Roaming\Microsoft\Windows\Start Menu\Programs
3. Right-click on your browser’s shortcut > Open Shortcut Properties > note the text in the “Start in” field (“C:\Users\PC Name\AppData\Local\Programs\Browser Name.exe”)
4. Add a single space after “exe,” then copy and paste the following flags into the “Start in” field: "--enable-features=AllowLegacyMV2Extensions,UnexpireFlagsM147,UnexpireFlagsM148,UnexpireFlagsM149 --disable-features=ExtensionManifestV2Unsupported,ExtensionManifestV2Disabled"
5. Double-check everything before clicking OK or Apply. Make sure the spacing and flags are entered exactly as shown in the guide for this method to work. If everything is correct, click OK in File Explorer.
6. Open the browser shortcut that now has the flags applied and pin that shortcut to the taskbar for easier access. Be sure to always open your browser via the pinned shortcut on the taskbar (the reason for this will be explained in Point B. Important Note).
7. Open the extensions menu in your browser. Next, enable developer mode in the top-right corner.
8. The DOM method uses developer mode, so every MV2 extension installation is performed offline without being tied to or influenced by the Chrome Web Store. Here are the two installation paths for the DOM method:

a. Extension repository path. This method uses the (.zip) file of the MV2 extension available on a repository site (GitHub, Codeberg, GitFlic, etc.). To download it, click the “Releases” section on the right side of the repository and download the extension’s ZIP file, or click the green icon > “Download ZIP.” I highly recommend creating a dedicated folder on your Windows PC to store all MV2 extension ZIP files so you don’t have trouble finding them later. Once downloaded, extract the .zip file using File Explorer’s built-in features or software like 7-Zip. Return to the extensions page in your browser > click “Load Unpacked” > locate the folder containing the extracted MV2 extension .zip files > click “Select Folder.” If steps 1–7 were followed correctly, the MV2 extension will be active and ready to use.

b. CRX extraction method. This second method is a solution if you cannot find the repository site for the MV2 extension you want to install. First, install the CRX Extractor/Downloader extension. Second, search for the extension’s page in the Chrome Web Store (note: the MV2 extension page has been hidden by Google and cannot be found manually via search, so you’ll need a special search link like Chrome-Stats. Open the extension page > Click CRX Extractor/Downloader on your browser’s extension bar > click “download as ZIP.” I highly recommend choosing the .zip format because it will make installation in developer mode much easier. Wait for the download to complete. Once downloaded, move the ZIP file to your dedicated MV2 folder and, as in path a: extract the ZIP > click “Load Unpacked” > locate the extracted .zip folder with the .mv2 extension > click “Select Folder.”

B. Important Notes

1. This DOM method works as long as Chromium version 150 still supports the shortcut flag. If future Chromium updates (151, 152, and so on) remove this flag’s functionality, this method will automatically stop working. I’ll provide an alternative solution in the future in further explanation in section C.
2. Based on Point A.6, this method relies entirely on the shortcut you created earlier. Therefore, make sure not to delete your browser shortcut. Pin your browser shortcut so you don’t forget its location. Get into the habit of opening your browser via the shortcut on the taskbar to make it easier for you to maintain MV2.
3. The MV2 extension installed via the DOM method cannot update automatically like the MV3 extension from the Chrome Web Store. If you want to update the MV2 extension, find the extension’s repository site or the dedicated Chrome Web Store page (see step A. 8. b), then update it manually (repeat step A. 8).
4. If you want to stay on this version to protect your extensions from Chromium updates and do not want to update your browser, follow this youtube guide to disable automatic browser updates. If your browser uses a different update mechanism, please search for a tutorial on Reddit or other sources. I do not recommend this. Understand the risks of not updating your browser. Always keep your PC’s antivirus software up to date and be cautious of malicious links

C. Alternative Solutions for the Future

If you read this guide in the future and it doesn’t work, there are three possible solutions:

1. Use an older browser version that still supports extensions via the DOM method. As mentioned in point B.4, be aware of the drawbacks and risks of using an older browser version.
2. If you want to continue using MV2 extensions but don’t want to use an older browser version, I recommend several alternative browsers that support MV2 manifest extensions as of the publication of this article:

a. Helium Browser. Based on my observations, this browser still fully supports all MV2 extensions without needing to use the DOM method. If you want functionality similar to Google Chrome but with full MV2 support, I highly recommend this browser because it comes with built-in uBlock Origin and randomized fingerprinting protection like Brave (enable it at helium://flags and search for helium-noise). In my opinion, the downside of this browser is the lack of DRM.

b. Gecko-based browsers. Use this type of browser because, as of the publication of this article, MV2 extensions can still be used fully without any issues. If you want to switch to a Gecko browser, you’ll need to get used to the new browser. Take some free time to familiarize yourself with the UI and UX so you can adapt smoothly.

C. Additionally, you can install Chrome extensions (.crx) in Gecko-based browsers using the CRX Installer add-on. There are five browsers that support this: Waterfox, Zen Browser, Firefox Nightly, Firefox Developer Edition, and Librewolf. After installing the CRX Installer, change the about:config setting xpinstall.signatures.required to false, then install both MV2 and MV3 Chrome extensions in your browser. This method works for most extensions, but some may not function properly. Hopefully, this guide will make your migration to a Gecko-based browser easier.

That concludes the guide I have to share. If anything is still unclear, feel free to discuss it with me. Thank you.