Pale Moon and SeaMonkey user agents
Pale Moon and SeaMonkey are independent browsers in the Gecko/Mozilla lineage. Pale Moon uses a Gecko-derived engine and SeaMonkey is an all-in-one internet suite. Their user-agent strings carry Gecko-family tokens together with their own product tokens (Goanna/PaleMoon for Pale Moon, SeaMonkey for SeaMonkey), distinguishing them from mainstream Firefox.
What this means
Pale Moon is an independent browser built on a fork of Gecko (its engine is called Goanna), aimed at users who want a more traditional, customisable Firefox-like experience. SeaMonkey is a community-maintained all-in-one internet suite — browser, mail, and more — descended from the original Mozilla Application Suite.
Both share the Gecko heritage, so their user agents look Firefox-adjacent. The distinguishing detail is each one's own product token rather than a plain Firefox token.
How they appear
Expect a Mozilla/5.0 prefix and Gecko-family tokens. Pale Moon strings include a PaleMoon and/or Goanna token; SeaMonkey strings include a SeaMonkey token. Some builds may also carry a Firefox compatibility token for sites that gate on Firefox, which is exactly why you should match the specific product token first.
Match on the stable product token, not a version. The full string is a claim and can be copied.
- Pale Moon: PaleMoon and/or Goanna engine token
- SeaMonkey: SeaMonkey product token
- May include a Firefox compatibility token on some builds
How it appears in analytics and logs
A Gecko-style user agent carrying a PaleMoon/Goanna token or a SeaMonkey token indicates one of these independent browsers. Both are real human browsers with small but real user bases, not bots.
Diagnostic use case
Attribute Gecko-family niche browser traffic to Pale Moon or SeaMonkey rather than lumping it under Firefox, and recognise their distinct product tokens.
What WebmasterID can help detect
WebmasterID can keep Pale Moon and SeaMonkey distinct from Firefox in browser-family reporting, so niche Gecko-family usage is not silently merged into mainstream Firefox.
Common mistakes
- Bucketing Pale Moon or SeaMonkey as Firefox because of a Firefox compatibility token.
- Assuming Gecko-family means identical capabilities to current Firefox.
- Matching a version instead of the stable product token.
Privacy and accuracy notes
These product tokens reveal only the browser family. They carry no visitor identity. WebmasterID reads them as coarse browser context only.
Related pages
- Firefox user agent pattern
Firefox's user agent is built around the Gecko engine token and a trailing Firefox product token. Compared with other browsers it has been relatively stable and predictable, which makes it straightforward to recognise. This page covers the pattern and how to tell Firefox apart from WebKit and Chromium clients.
- Browser user agents: how to read them
A browser user-agent string packs several tokens into one line: a legacy Mozilla prefix, a rendering-engine signature, the platform, and the browser itself. This page explains each part so you can read a UA without over-reading it, because the contents are client-controlled and can be copied by any client.
- User agent sniffing pitfalls
User-agent sniffing means changing site behaviour based on substrings in the User-Agent header. It is fragile: it misfires on new or unexpected browsers, breaks as user agents are reduced, and is easily defeated by spoofing. Feature detection and Client Hints are more robust approaches for most cases.
- Privacy-first analytics
Keep niche browser families visible as coarse context.
Sources and verification notes
- Pale Moon — official sitePale Moon uses the Goanna engine; SeaMonkey is the Mozilla suite. Tokens described generally, versions not pinned.
- SeaMonkey project
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.