WebGL 1.0 is supported in the stable releases of most major browsers on both desktop and mobile platforms. Chrome, Firefox, Internet Explorer, Opera, and Safari are all known to have good WebGL support on both desktop and mobile browsers. See http://caniuse.com/#feat=webgl for availability details.
Technical issues such as known hardware problems or lack of required GPU features may prevent WebGL from running in some cases.
The WebGL 2.0 specification has recently been released, and implementations of the new API are becoming available.
WebGL 2.0 requires hardware with OpenGL ES 3.0 support or comparable desktop OpenGL feature support. Not all systems capable of running WebGL 1.0 will be able to run WebGL 2.0. See http://caniuse.com/#feat=webgl2 for availability details.
WebGL 2.0 is first supported in Firefox 51. Please file bugs for any issues you discover with Firefox’s WebGL 2.0 implementation at https://bugzilla.mozilla.org/.
WebGL 2.0 is first supported on desktop platforms in Chrome 56. As of this writing, it may be enabled on Android by navigating to about:flags, finding the entry for "WebGL 2.0", and changing the setting from "Default" to "Enabled".
Please file bugs for any issues you discover with Chrome's WebGL 2.0 implementation at https://crbug.com. In addition to describing the problem, please navigate to about:gpu and attach the contents of that page to your report, which will help the developers identify the problem in the case that the issue is GPU or OS specific.
Here are a few links to demos using WebGL 2.0 with which you can verify that your browser has it properly enabled.