For more information, please visit the following pages:

• Firefox
• Mozilla Foundation
• Gecko

Latest user agents (if you are looking for complete list, download it here):

• Mozilla/5.0 (Linux i686; rv:15.0) Gecko/20141115 Firefox/15.0
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6.9; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.7.3; rv:15.0) Gecko/20100101 Firefox/15.0.9
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6.3; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.8.6; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9.1; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.9; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.8.9; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5.2; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7.6; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5.8; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.8.5; rv:15.0) Gecko/20100101 Firefox/15.0.9
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7.2; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6.6; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5.5; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9.9; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.9.1; rv:15.0) Gecko/20100101 Firefox/15.0.9
• Mozilla/5.0 (Macintosh; PPC Mac OS X 10.7.6; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6.1; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Linux i686; rv:15.0) Gecko/2007815 Firefox/15.0
• Mozilla/5.0 (Windows NT 6.3; WOW64; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.7.6; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.10.6; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.7.3; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8.1; rv:15.0) Gecko/20100101 Firefox/15.0.1
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
• Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6.6; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7.5; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5.0; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.7.5; rv:15.0) Gecko/20100101 Firefox/15.0.0
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.9.1; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6.9; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6.4; rv:15.0) Gecko/20100101 Firefox/15.0.0
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7.6; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Windows NT 6.1; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5.6; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8.6; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6.5; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8.4; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.10.4; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.10.5; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6.2; rv:15.0) Gecko/20100101 Firefox/15.0.0
• Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9.9; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.9.1; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.10.3; rv:15.0) Gecko/20100101 Firefox/15.0.0
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.8; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6.0; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.8.5; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6.9; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6.0; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8.7; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5.5; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.5; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5.8; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.9; rv:15.0) Gecko/20100101 Firefox/15.0.5
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6.8; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.9.8; rv:15.0) Gecko/20100101 Firefox/15.0.9
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.2; rv:15.0) Gecko/20100101 Firefox/15.0.1
• Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Windows NT 6.3; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.5.6; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9.5; rv:15.0) Gecko/20100101 Firefox/15.0.1
• Mozilla/5.0 (Windows NT 6.0; rv:15.0) Gecko/20100101 Firefox/15.0.0
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7.3; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Windows NT 5.1; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.7.5; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.6; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Windows NT 6.0; Win64; x64; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.6; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Windows NT 6.0; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6.4; rv:15.0) Gecko/20100101 Firefox/15.0.9
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.8.6; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Windows NT 5.1; Win64; x64; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5.6; rv:15.0) Gecko/20100101 Firefox/15.0.4
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5.2; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Windows NT 6.0; Win64; x64; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9.9; rv:15.0) Gecko/20100101 Firefox/15.0.9
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.10.0; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.9.1; rv:15.0) Gecko/20100101 Firefox/15.0.0
• Mozilla/5.0 (Windows NT 5.2; WOW64; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.7.4; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5.5; rv:15.0) Gecko/20100101 Firefox/15.0.0
• Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20100101 Firefox/15.0.0
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.7.0; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Windows NT 5.2; WOW64; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7.2; rv:15.0) Gecko/20100101 Firefox/15.0.1
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.10.6; rv:15.0) Gecko/20100101 Firefox/15.0.2
• Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6.6; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; PPC Mac OS X 10.9.7; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.8; rv:15.0) Gecko/20100101 Firefox/15.0.7
• Mozilla/5.0 (Windows NT 5.2; rv:15.0) Gecko/20100101 Firefox/15.0.3
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9.9; rv:15.0) Gecko/20100101 Firefox/15.0.6
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10.1; rv:15.0) Gecko/20100101 Firefox/15.0.8
• Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8.7; rv:15.0) Gecko/20100101 Firefox/15.0.4