When can I use… Compatibility tables for support of HTML5, CSS3, SVG and more in desktop and mobile browsers.
You have to target a specific browser and you want to know if this browser supports a feature or not? The Can I Use website is the only thing you need.
Just enter the name of a feature (e.g. Geolocation) in the Search box and you’ll get a nice overview with all the browsers(including mobile versions) and their support.
Remark: I still recommend to use feature detection inside your web application(with Modernizr for example).