Every Firefox extension goes through a review process before it is listed on addons.mozilla.org (AMO). Here is how the Firefox review process works and how it compares to Chrome's.
Firefox AMO review process
Automatic validation:
Every submitted extension runs through an automated validator that checks for known security issues, deprecated APIs, and policy violations. This runs immediately on upload.
Manual code review:
AMO reviewers read the extension's source code. For new extensions and major updates, a human reviewer looks at every file. This is not a cursory scan — reviewers can and do request changes.
Review timeline:
New extensions typically wait days to weeks for initial review. The timeline depends on queue volume. Updates to already-approved extensions are often reviewed faster.
What reviewers check:
- Code execution paths
- Network requests (what data is sent where)
- Permissions (are they justified by the extension's function)
- Obfuscated code (not allowed)
- Remote code execution (not allowed)
Chrome Web Store review process
Chrome's review is more automated and faster but historically less rigorous. Extensions can be approved in hours. The tradeoff is that more malicious extensions have historically made it through Chrome's process.
Chrome has tightened reviews after high-profile incidents, but the fundamental difference remains: AMO does deep manual code review; CWS relies more heavily on automated scanning.
The "Recommended" badge
AMO offers a "Recommended" badge for extensions that pass an additional quality review. Criteria include:
- Security (clean code, no suspicious patterns)
- Performance (no memory leaks, no slow operations)
- User experience (clear permissions, honest description)
- Active maintenance
Recommended extensions appear higher in AMO search results. Getting the badge requires nomination and passing a thorough review.
Implications for users
The manual AMO review process means:
- Lower probability of a malicious extension passing review
- Clear rejection criteria (extensions know why they were rejected)
- Higher friction for developers (slower time to list)
For users, AMO's stricter review is a meaningful safety signal.
The 11 Firefox extensions in this series are all reviewed and listed on AMO — see the full series.
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