Looking for support tables for HTML/CSS/JavaScript features or details on their implementation status in major browsers?
- Chrome Platform Status (covers Chromium and thus includes Opera)
- Firefox Platform Status
- Microsoft Edge Platform Status
- WebKit Feature Status
- API Catalog
And then there’s Can I use…?.
The official MDN repository: https://github.com/mdn/browser-compat-data
A related Stack Overflow post: Where can I track the status of features (including in-development) in major browsers?