A C# random user agent provider, useful for testing web API's and how they handle different types of devices.

UserAgent.cs

public class UserAgent
{
    private static readonly string[] UserAgents =
    [
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.1 (KHTML, like Gecko) Chrome/4.0.219.6 Safari/532.",
        "Opera/9.80 (Windows NT 5.2; U; ru) Presto/2.5.22 Version/10.5",
        "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.3) Gecko/20090913 Firefox/3.5.",
        "Mozilla/5.0 (Windows; U; Windows NT 6.1; ru; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 2.0.50727",
        "Mozilla/5.0 (Windows; U; Windows NT 5.2; de-de; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729",
        "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.1) Gecko/20090718 Firefox/3.5.1 (.NET CLR 3.0.04506.648",
        "Opera/9.60 (J2ME/MIDP; Opera Mini/4.2.14912/812; U; ru) Presto/2.4.1",
        "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en-US) AppleWebKit/125.4 (KHTML, like Gecko, Safari) OmniWeb/v563.5",
        "Mozilla/5.0 (SymbianOS/9.2; U; Series60/3.1 NokiaN95_8GB/31.0.015; Profile/MIDP-2.0 Configuration/CLDC-1.1 ) AppleWebKit/413 (KHTML, like Gecko) Safari/41",
        "Mozilla/5.0 (Windows; U; WinNT4.0; en-US; rv:1.8.0.5) Gecko/20060706 K-Meleon/1.",
        "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; de-de) AppleWebKit/418 (KHTML, like Gecko) Shiira/1.2.2 Safari/12",
        "Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.8.1.6) Gecko/2007072300 Iceweasel/2.0.0.6 (Debian-2.0.0.6-0etch1+lenny1",
        "Mozilla/5.0 (SymbianOS/9.1; U; en-us) AppleWebKit/413 (KHTML, like Gecko) Safari/41",
        "Mozilla/1.22 (compatible; Konqueror/4.3; Linux) KHTML/4.3.5 (like Gecko",
        "Opera/9.80 (Macintosh; U; de-de) Presto/2.8.131 Version/11.1",
        "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100318 Mandriva/2.0.4-69.1mib2010.0 SeaMonkey/2.0.",
        "Mozilla/4.0 (compatible; MSIE 6.1; Windows XP) Gecko/20060706 IEMobile/7.",
        "Mozilla/5.0 (iPad; U; CPU OS 3_2 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Version/4.0.4 Mobile/7B334b Safari/531.21.1",
        "Mozilla/4.0 (Macintosh; U; Intel Mac OS X 10_6_7; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.205 Safari/534.1",
        "Mozilla/1.22 (X11; U; Linux x86_64; en-US; rv:1.9.1.1) Gecko/20090718 Firefox/3.5.",
        "Mozilla/5.0 (Windows; U; Windows NT 6.0; en; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.",
        "Mozilla/3.0 (Windows NT 6.1; ru-ru; rv:1.9.1.3.) Win32; x86 Firefox/3.5.3 (.NET CLR 2.0.50727",
        "Opera/9.80 (Windows NT 5.1; U; en-US) Presto/2.8.131 Version/11.1",
        "Mozilla/5.0 (Windows; U; Windows CE 4.21; rv:1.8b4) Gecko/20050720 Minimo/0.00",
        "Mozilla/5.0 (compatible; 008/0.83; http://www.80legs.com/webcrawler.html) Gecko/200803262",
        "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) AddSugarSpiderBot www.idealobserver.co",
        "Mozilla/5.0 (compatible; U; ABrowse 0.6; Syllable) AppleWebKit/420+ (KHTML, like Gecko",
        "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; Acoo Browser; GTB6; Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1) ; InfoPath.1; .NET CLR 3.5.30729; .NET CLR 3.0.30618",
        "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en) AppleWebKit/419 (KHTML, like Gecko, Safari/419.3) Cheshire/1.0.ALPH",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.2 (KHTML, like Gecko) ChromePlus/4.0.222.3 Chrome/4.0.222.3 Safari/532.",
        "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 ChromePlus/1.5.1.",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194",
        "Mozilla/5.0 (Windows NT 6.3; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.4.",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 (FM Scene 4.6.1",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 (.NET CLR 3.5.30729) (Prevx 3.0.5)",
        "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.1.8) Gecko/20071004 Iceweasel/2.0.0.8 (Debian-2.0.0.6+2.0.0.8-Oetch1",
        "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.8.0.1) Gecko/20060111 Firefox/1.5.0.",
        "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; acc=baadshah; acc=none; freenet DSL 1.1; (none)",
        "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; en) Opera 8.5",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.1) Gecko/20060111 Firefox/1.5.0.",
        "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; ja-jp) AppleWebKit/417.9 (KHTML, like Gecko) Safari/417.",
        "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051010 Firefox/1.0.7 (Ubuntu package 1.0.7",
        "Mozilla/5.0 (Windows; U; Windows NT 6.1; en; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729",
        "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729",
        "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.1) Gecko/20090718 Firefox/3.5.",
        "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.1) Gecko/20061205 Iceweasel/2.0.0.1 (Debian-2.0.0.1+dfsg-2",
        "Opera/10.00 (X11; Linux i686; U; en) Presto/2.2.",
        "Mozilla/5.0 (Windows; U; Windows NT 6.0; he-IL) AppleWebKit/528.16 (KHTML, like Gecko) Version/4.0 Safari/528.1",
        "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101209 Firefox/3.6.1",
        "Mozilla/5.0 (Windows; U; Windows NT 6.1; ru; rv:1.9.2.3) Gecko/20100401 Firefox/4.0 (.NET CLR 3.5.30729",
        "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.8) Gecko/20100804 Gentoo Firefox/3.6.",
        "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.7) Gecko/20100809 Fedora/3.6.7-1.fc14 Firefox/3.6.",
        "Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2049.0 Safari/537.3",
        "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.67 Safari/537.3",
        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.9 Safari/536.",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_0) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.",
        "Mozilla/5.0 (Windows NT 5.1; rv:31.0) Gecko/20100101 Firefox/31.",
        "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:29.0) Gecko/20120101 Firefox/29.",
        "Mozilla/5.0 (X11; OpenBSD amd64; rv:28.0) Gecko/20100101 Firefox/28.",
        "Mozilla/5.0 (X11; Linux x86_64; rv:28.0) Gecko/20100101  Firefox/28.",
        "Mozilla/5.0 (Windows NT 6.1; rv:27.3) Gecko/20130101 Firefox/27.",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:25.0) Gecko/20100101 Firefox/25.",
        "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:24.0) Gecko/20100101 Firefox/24.",
        "Mozilla/5.0 (BlackBerry; U; BlackBerry 9900; en) AppleWebKit/534.11+ (KHTML, like Gecko) Version/7.1.0.346 Mobile Safari/534.11",
        "Mozilla/5.0 (BlackBerry; U; BlackBerry 9850; en-US) AppleWebKit/534.11+ (KHTML, like Gecko) Version/7.0.0.254 Mobile Safari/534.11",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/535.7 (KHTML, like Gecko) Comodo_Dragon/16.1.1.0 Chrome/16.0.912.63 Safari/535.",
        "Mozilla/5.0 (X11; U; Linux x86_64; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Comodo_Dragon/4.1.1.11 Chrome/4.1.249.1042 Safari/532.",
        "Mozilla/5.0 (iPad; CPU OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A5355d Safari/8536.2",
        "Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/537.13+ (KHTML, like Gecko) Version/5.1.7 Safari/534.57.",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/534.55.3 (KHTML, like Gecko) Version/5.1.3 Safari/534.53.1",
        "Mozilla/5.0 (iPad; CPU OS 5_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko ) Version/5.1 Mobile/9B176 Safari/7534.48.",
        "Mozilla/5.0 (Windows; U; Windows NT 6.1; tr-TR) AppleWebKit/533.20.25 (KHTML, like Gecko) Version/5.0.4 Safari/533.20.2",
        "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; en) Opera 8.",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.5) Gecko/20031007 Firebird/0.",
        "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20060205 Galeon/2.0.0 (Debian package 2.0.0-2",
        "Mozilla/5.0 (X11; U; NetBSD i386; en-US; rv:1.8.0.1) Gecko/20060310 Firefox/1.5.0.",
        "Mozilla/5.0 (X11; U; IRIX64 IP27; en-US; rv:1.4) Gecko/2003071",
        "Opera/5.0 (SunOS 5.8 sun4m; U) [en",
        "Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:1.7) Gecko/2005112",
        "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; de) Opera 8.5",
        "Mozilla/5.0 (Windows; U; Windows NT 5.2; de; rv:1.8.0.1) Gecko/20060111 Firefox/1.5.0.",
        "Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8) Gecko/20060202 Firefox/1.",
        "Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.0.1) Gecko/20060111 Firefox/1.5.0.",
        "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; en) Opera 8.5",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; de-DE; rv:1.7.12) Gecko/20050919 Firefox/1.0.",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.0.1) Gecko/20060111 Firefox/1.5.0.",
        "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051008 Firefox/1.0.",
        "Mozilla/4.0 (compatible; MSIE 6.0; X11; Linux i686; en) Opera 8.5",
        "Mozilla/5.0 (compatible; Konqueror/3.4; Linux) KHTML/3.4.3 (like Gecko",
        "Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.0.1) Gecko/20060130 SeaMonkey/1.",
        "Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.0.1) Gecko/20060130 SeaMonkey/1.0,gzip(gfe) (via translate.google.com",
        "Mozilla/5.0 (Windows; U; Windows NT 5.0; de; rv:1.8.0.1) Gecko/20060111 Firefox/1.5.0.",
        "Mozilla/5.0 (Windows; U; Windows NT 5.0; de-DE; rv:0.9.4.1) Gecko/2002050",
        "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; de-de) AppleWebKit/125.2 (KHTML, like Gecko",
        "Mozilla/5.0 (X11; U; Linux i686; de-DE; rv:1.4) Gecko/2003062",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; de-DE; rv:1.7.6) Gecko/20050321 Firefox/1.0.",
        "Mozilla/5.0 (X11; U; Linux i686; de-AT; rv:1.7.12) Gecko/20051013 Debian/1.7.12-1ubuntu",
        "Mozilla/5.0 (Windows; U; Windows NT 5.0; de; rv:1.8) Gecko/20051111 Firefox/1.",
        "Mozilla/5.0 (Windows; U; Windows NT 5.0; de-DE; rv:0.9.4.1) Gecko/20020508 Netscape6/6.2.",
        "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; de) Opera 8.5",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8) Gecko/20051111 Firefox/1.",
        "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; de) Opera 8.5",
        "Mozilla/5.0 (Windows; U; Windows NT 5.1; de-DE; rv:1.4) Gecko/20030619 Netscape/7.1 (ax",
        "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en) AppleWebKit/312.8 (KHTML, like Gecko) Safari/312.",
    ];

    public static string GetRandom() => Random.Shared.GetItems(UserAgents, 1).First();
}