Site24x7 Web Transaction (Browser) and Web Page Speed (Browser) monitors use the following user agents for monitoring,
FFV83 - Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0.247) Gecko/20100101 Firefox/83.0 Site24x7
ChromeV88 - Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0 Safari/537.36.247 Site24x7
Mobile Resolution
IPhone 6/7/8
Chrome :"Mozilla/5.0 (iPhone; CPU iPhone OS 13_2_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.3 Mobile/15E148 Safari/604.1 Site24x7",
Firefox:"Mozilla/5.0 (iPhone; CPU iPhone OS 14_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.3 Mobile/15E148 Safari/604.1 Site24x7"
IPhone 12/13 + Pro
Chrome :Mozilla/5.0 (iPhone; CPU iPhone OS 13_2_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.3 Mobile/15E148 Safari/604.1 Site24x7
Firefox:Mozilla/5.0 (iPhone; CPU iPhone OS 14_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.3 Mobile/15E148 Safari/604.1 Site24x7
IPhone X
Chrome :Mozilla/5.0 (iPhone; CPU iPhone OS 13_2_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.3 Mobile/15E148 Safari/604.1 Site24x7
Firefox:Mozilla/5.0 (iPhone; CPU iPhone OS 14_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.3 Mobile/15E148 Safari/604.1 Site24x7
Galaxy S20
chrome: Mozilla/5.0 (Linux; U; Android 4.1; en-us; GT-N7100 Build/JRO03C) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30 Site24x7
Firefox:Mozilla/5.0 (Linux; Android 11; SAMSUNG SM-G973U) AppleWebKit/537.36 (KHTML, like Gecko) SamsungBrowser/14.2 Chrome/88.0.4280.141 Mobile Safari/537.36 Site24x7
Pixel 2
Chrome: Mozilla/5.0 (Linux; Android 8.0.0; Pixel 2 XL Build/OPD1.170816.004) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Mobile Safari/537.36 Site24x7
Firefox:Mozilla/5.0 (Linux; Android 11; Pixel 2XL) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.152 Mobile Safari/537.36 Site24x7
Tab Resolution
IPad
Chrome: Mozilla/5.0 (iPad; CPU OS 11_0 like Mac OS X) AppleWebKit/604.1.34 (KHTML, like Gecko) Version/11.0 Mobile/15A5341f Safari/604.1 Site24x7
Firefox:Mozilla/5.0 (iPad; CPU OS 14_7_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1.2 Mobile/15E148 Safari/604.1 Site24x7
IPad Pro
Chrome: Mozilla/5.0 (iPad; CPU OS 11_0 like Mac OS X) AppleWebKit/604.1.34 (KHTML, like Gecko) Version/11.0 Mobile/15A5341f Safari/604.1 Site24x7
Firefox:Mozilla/5.0 (iPad; CPU OS 14_7_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1.2 Mobile/15E148 Safari/604.1 Site24x7
Surface Duo
Chrome:Mozilla/5.0 (Linux; Android 10; Surface Duo Build/2020.1211.85; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/88.0.4324.93 Mobile Safari/537.36 GSA/12.1.9.23.arm64 Site24x7
Firefox:Mozilla/5.0 (Linux; Android 10; Surface Duo) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.116 Mobile Safari/537.36 EdgA/45.11.4.5118 Site24x7
Desktop Resolution
1024,768
Chrome: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:94.0) Gecko/20100101 chrome/88.0 Site24x7
Firefox:Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:94.0) Gecko/20100101 Firefox/83.0 Site24x7
1366,768
Chrome: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:94.0) Gecko/20100101 chrome/88.0 Site24x7
Firefox:Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:94.0) Gecko/20100101 Firefox/83.0 Site24x7
1600,900
Chrome: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:94.0) Gecko/20100101 chrome/88.0 Site24x7,
Firefox:Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:94.0) Gecko/20100101 Firefox/83.0 Site24x7
1920,1080
Chrome: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:94.0) Gecko/20100101 chrome/88.0 Site24x7,
Firefox:Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:94.0) Gecko/20100101 Firefox/83.0 Site24x7
However, you can always specify a custom user agent (browser and version) in your Web Transaction (Browser) and Web Page Speed (Browser) monitor form to simulate different browser versions.