Fontanello browser extension is the quickest way to find out what font a webpage is using.

You simply right click on the text and Fontanello will reveal the name of the typeface and some additional attributes you likely care about.

On iPhone/iPad you just select (or tap) the letters that caught you attention and choose Fontanello icon in the menu you reach from address bar.

Done

Fontanello

Typeface
Intel One Mono
Weight
400 (normal)
Size
19.73px
Line height
1.38 (27.2274px)
Color
#222222
Contrast ratio
14.08 (AAA)
Letter spacing
-0.16px
Variants
normal
Features
"kern", "liga", "pnum", "onum"
Variables
normal