For an easy and thorough intro to Baseline, check out this talk by Rachel Andrew, but if you want the short version… Combining those 4 resources, you can get a definitive verdict on whether a browser feature is ready to go your client's site:
webstatus.dev: for Baseline status and dates, per-browser versions and ship dates, test summary scores, Chrome usage, and developer signals. The spine of every issue.
wpt.fyi: for the test data underneath those scores, and for when each browser was actually tested.
caniuse: when a verdict is close, because Baseline says “safe in the core browser set” and caniuse says “safe for 97.3% of real traffic.” That gap is exactly where a catastrophic-failure Hold lives.
MDN browser compat data: for the partial-implementation flags and per-subfeature notes that Baseline flattens away.
