User-Agent 首部包含了一個特征字符串，用來讓網絡協議的對端來識別發起請求的用戶代理軟件的應用類型、操作系統、軟件開發商以及版本號。
以下是一些常見的各種瀏覽器的User-Agent：
1) Chrome(谷歌)
Win7:
Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/14.0.835.163 Safari/535.1
Win10:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36
Chrome 17.0 – MAC
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_0) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11
2) Firefox(火狐)
Win7:
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0) Gecko/20100101 Firefox/6.0
Firefox 4.0.1 – MAC
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
3) Safari(Safari是蘋果計算機的操作系統Mac OS中的瀏覽器)
safari 5.1 – MAC
Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_8; en-us) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50
safari 5.1 – Windows
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-us) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50
4) Opera(歐朋瀏覽器可以在Windows、Mac和Linux三個操作系統平台上運行)
Opera 11.11 – MAC
User-Agent:Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; en) Presto/2.8.131 Version/11.11
Opera 11.11 – Windows
User-Agent:Opera/9.80 (Windows NT 6.1; U; en) Presto/2.8.131 Version/11.11
5) IE
IE 11
Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko
IE 9.0
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0;
IE 8.0
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0)
IE 7.0
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)
IE 6.0
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
WinXP+ie8：
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB7.0)
WinXP+ie7：
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)
WinXP+ie6：
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)
6) 傲游
傲游（Maxthon）
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Maxthon 2.0)
7) 搜狗
搜狗瀏覽器 1.x
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; SE 2.X MetaSr 1.0; SE 2.X MetaSr 1.0; .NET CLR 2.0.50727; SE 2.X MetaSr 1.0)
8) 360
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; 360SE)
9) QQ瀏覽器
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; TencentTraveler 4.0)