User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.7) Gecko/20100104 SeaMonkey/2.0.2 Build Identifier: At the top of many (all?) pages is the note: "We noticed that you're using an unsupported browser. The TripAdvisor website may not display properly. We support the following browsers: Windows: Internet Explorer, Mozilla Firefox. Mac: Safari." That note does not appear if I spoof using the following UA string: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.7) Gecko/20100104 SeaMonkey/2.0.2, NOT Firefox/3.5.6 Reproducible: Always

I have contacted the site owner about this problem.

Oops! Incomplete Summary fixed.

The message is still there when faking UA with SeaMonkey. → http -b GET http://www.tripadvisor.com/ 'User-Agent: Mozilla/5.0 (X11; Linux i686; rv:32.0) Gecko/20100101 SeaMonkey/2.29' | egrep -i unsupported <div class="unsupportedBrowser" style="width:973px; margin:0 auto 20px; padding:5px; background-color:#ffe5a5; font-size:.75em;"> <b>We noticed that you're using an unsupported browser. The TripAdvisor website may not display properly.</b><br/> We support the following browsers: <b>We noticed that you're using an unsupported browser. The TripAdvisor website may not display properly.</b><br/> We support the following browsers: → http -b GET http://www.tripadvisor.com/ 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:32.0) Gecko/20100101 Firefox/32.0' | egrep -i unsupported [nothing returned]

Tripadvisor should just send the normal content to browser such as SeaMonkey. They could either detect specifically SeaMonkey as an authorized browser or Gecko/version number. But better would be to not detect at all on User Agent strings and just rely on feature detections.

Still an issue, still contactready. I guess many Gecko-based browsers have added a "like Firefox"-type string at this point though.

Looks like the message has been fixed or removed.

Windows 7 Ultimate SP1 (x64) Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 SeaMonkey/2.49.1 I still get that banner at the top of the page unless I enable "Advertise Firefox compatibility". This proves that the site is sniffing for "Firefox" and not "Gecko".