Start with the feature your app needs
Run the Browser Compatibility Check. Its percentage counts exposed features. Missing a newer optional API does not make a browser unsuitable for normal browsing, and another app may not need that API at all.
Support is different from permission
A camera API can exist even when the site is blocked from using it. Confirm camera and microphone access through the Webcam Test and Microphone Test. Some features need HTTPS, a direct user gesture or an organisational policy allowance.
Storage presence is not a storage test
Seeing IndexedDB support means the interface is exposed. It does not prove a write succeeds, show the available quota or promise that data will persist. This tool does not measure free disk space. Private browsing, site settings and storage pressure may change what an app can retain.
Compare a controlled setup
Try the affected app after checking its permissions and saving any open work. If it works in another browser profile, extensions or settings may be involved. On managed devices, ask support about restrictions. Do not remove security controls broadly just to improve a compatibility score.
Describe a useful bug report
Include the failing feature, browser version and steps that reproduce the issue. The Device Info page can help you inspect browser-exposed information, but review it before sharing. Do not send browsing history, passwords or confidential files. A clear error message helps more than an unexplained percentage.