CrossDevice Usage Journal - Daily SaaS Ideas

Privacy-friendly app usage and program time tracking unified across desktop and mobile with local-first sync and weekly focus reports.

Platform: web

Reddit (Jan 2024) – r/software thread titled “Looking for cross-platform time-tracking app (Android & Windows)”. Most-up-voted answers mention StayFree and ActivityWatch but users complain about *cloud-first* or difficult syncing.
Reddit (Dec 2022) – r/productivity post supplied by the requester (“is there an app that tracks usage of apps?”) – several replies say they cannot find one that works across both phone and desktop while keeping data local. Up-votes ≈ 350.

These posts show real, recent demand for exactly “one journal of usage across all devices, privacy-friendly, local-first sync”.

Keyword	Global volume	Difficulty	Meets rule?
app usage iphone	590	12	✅ (>500 vol, <30 diff)
app usage android	590	31	⚠️ (slightly over diff limit)
app usage tracker	210	14	volume a bit low, still relevant
digital wellbeing app	2 400	36	difficulty a bit high
screen time tracker	480	43	diff too high

At least one core keyword (“app usage iphone”) satisfies the ≥500 / <30 rule...