Publishing a Firefox Extension in AMO: Preparation and Review

Publishing a Firefox Extension in AMO

Your Chrome extension works perfectly, but when porting to Firefox you get an error: Missing browser_specific_settings.gecko.id. Or AMO upload is rejected due to missing source code. Sound familiar? We've faced this many times and know how to pass review on the first try. In this article we'll break down the technical nuances of publishing in Firefox Add-ons and show how we help clients ship a turnkey extension in 3–5 days.

Unlike Chrome Web Store, AMO requires mandatory extension ID in the manifest and supports both MV2 and MV3. But the key difference is the need for Mozilla signing even for self-distribution. Without signing, Firefox simply refuses to install the XPI. Based on our experience, 80% of extensions are rejected due to minor issues: missing ID, wrong manifest version, or missing source code.

In this article we'll detail every step from account creation to obtaining Recommended status. And if you want to save time — our team is ready to handle all the routine: from audit to final deployment. Contact us — we'll assess your project in one day.

Why Publishing in AMO Is Harder Than in Chrome Web Store?

Firefox uses its own manifest and signing system. Key points:

• The browser_specific_settings.gecko.id field is mandatory — without it the extension won't get updates.
• Extensions with bundling require separate source code.
• Mozilla signing is required even for self-distribution — without it the extension won't install.

We guarantee that after our preparation the extension will pass review without extra requests. Our engineers have 7 years of extension development experience and have published over 50 extensions on AMO.

What Problems Do We Solve?

• Incorrect manifest. Often developers forget to specify browser_specific_settings or use an invalid ID. We check and fix.
• Missing signature. For corporate distribution you need a signed extension. We set up web-ext and CI/CD for automation.
• Review rejection. Due to obfuscated code without source or excessive permissions. We prepare packages to AMO requirements.

How We Prepare the Extension: Stack and Case Study

For cross-browser compatibility we use webextension-polyfill. This package wraps Chrome API into promises and normalizes differences. For example, here's the manifest with polyfill:

{ "manifest_version": 2, "browser_specific_settings": { "gecko": { "id": "[email protected]", "strict_min_version": "91.0" } } } 

// webextension-polyfill import browser from 'webextension-polyfill'; // Now APIs are unified for Chrome and Firefox 

We automate signing via web-ext:

web-ext sign \ --source-dir ./dist \ --artifacts-dir ./signed \ --api-key $AMO_API_KEY \ --api-secret $AMO_API_SECRET 

Work Process: From Audit to Deployment

Total: 3–7 business days.

Timeline and Cost

Cost depends on extension complexity and required modifications. We provide free project assessment in 1 day. Typically the full cycle takes 3 to 7 days. Contact us — we'll give exact timelines after audit.

What's Included in the Work

• Compatibility audit with Firefox
• Manifest and code fixes
• Source code and ZIP package preparation
• Automatic signing setup (web-ext, CI)
• Review passing (automated + manual if needed)
• Maintenance documentation
• 30 days of support after publication

Comparison of MV2 and MV3 in Firefox

Typical Publication Mistakes

• Missing browser_specific_settings.gecko.id
• Uploading ZIP without source (for bundling)
• Using deprecated MV2 without migration plan
• Requesting excessive permissions (host_permissions)
• Missing signature for self-distribution

We'll help you avoid these mistakes guaranteed.

According to Mozilla documentation, signing is mandatory for all extensions, including self-distribution.