User Agent String explained :
 Firefox 3.5.5 | |
|---|---|
| Mozilla | MozillaProductSlice. Claims to be a Mozilla based user agent, which is only true for Gecko browsers like Firefox and Netscape. For all other user agents it means 'Mozilla-compatible'. In modern browsers, this is only used for historical reasons. It has no real meaning anymore |
| 5.0 | Mozilla version |
| Windows | Platform |
| U | Security values:
|
| Windows NT 5.1 | Operating System:  Windows XP |
| en-US | Language Tag, indicates the language for which the client had been localized (e.g. menus and buttons in the user interface) en-US =  English - United States |
| rv:1.9.1.5 | CVS Branch Tag The version of Gecko being used in the browser |
| Gecko | Gecko engine inside |
| 20091102 | Build Date: the date the browser was built |
| MRA | Mail.ru Agent - Instant Messenger |
| 5.5 | MRA version |
| build 02842 | MRA build |
| Firefox | Name : Firefox |
| 3.5.5 | Firefox version |
| First visit: | 2009.12.21 03:28 |
| Last visit: | 2025.09.13 06:08 |
All Firefox user agent strings | |