Checklist: Device detection — User-Agent parsing vs Client Hints

Checklist: Device detection — User-Agent parsing vs Client Hints

User-Agent string parsing:
☐ Works everywhere today, every traffic type
☐ Increasingly frozen/reduced by Chrome — model details vanishing
☐ Library (uap, DeviceDetector) needs monthly updates or new devices misclassify

Client Hints (Sec-CH-UA headers):
☐ Accurate, structured, future-proof for Chrome
☐ Requires the browser to send them — bots and old browsers won't
☐ Needs a server opt-in header to get full detail

Step — Run both: parse UA as the baseline, enrich with Client Hints when present, never depend on Hints alone.
Step — Decide granularity. iOS vs Android is reliable everywhere. Exact model (iPhone 15 vs 14) is not — don't route on it.

Tradeoff: UA parsing has coverage but decaying accuracy; Client Hints have accuracy but partial coverage.

Update your detection library monthly; re-test on a fresh device matrix quarterly.