Case study · Product
Chain.
A focus app for Windows and Android. Focused hours raise a castle for each of your projects.
- Year
- 2026
- Role
- Solo developer · product, design, engineering and releases
- Stack
- Tauri · React / TypeScript · Rust / Kotlin · SQLite · Supabase
- Hours of focus
- 1,160
- Focus sessions
- 943
- Users
- 20
15 active in the past 30 days
Green figures show the last 30 days. Cloud-synced sessions, my own included.How this is measured
Updated 14 October 2026 at 05:15 UTC. Totals refresh about every five minutes. Focus totals cover all-time banked sessions synced to the cloud, including my own use; offline-only work is excluded. Deleted and anonymous accounts are excluded. Active means cloud sync activity in the past 30 days, not necessarily a focus session. Growth compares these totals with totals 30 days before the update above, using a rolling window of 30 × 24 hours. The baseline is reconstructed from currently surviving synced sessions completed before that cutoff, on accounts registered before that cutoff. Edits, deletions and late sync can revise it; it is not a stored historical snapshot.
Start with the work. Pick a project, set an intention and begin. Each day of focus adds a link to the chain.
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Android FocusTap to view larger ↗
From my own timer to a product
I built Chain to give myself a reason to come back to focused work tomorrow. Now strangers use it too.
- Start. Pick a project, set an intention, begin.
- Watch it add up. A daily chain, castles that rise with your hours, milestones you earn.
- Take it along. Works offline, syncs, and hands a running session between devices.
The Windows and Android releases and the Microsoft Store listing all shipped on 2 October 2026.
Under the timer
Both apps share one TypeScript core for time, sessions, progress and sync, so the rules can't drift between devices. Tauri, Rust and Kotlin handle the native parts.
- Local first. Recording work never waits on the network.
- Recovery. Interrupted sessions get reconciled, and history survives every upgrade.
- Privacy. Friends only see what you share. This site only sees totals.
By switching from a bundled WebView2 runtime to the one Windows already has.
A backlog shaped by users
Tradeoffs
One core, two very different screens. Desktop has room for a full-screen focus room. Android needs bigger buttons and has to survive the screen locking mid-session.
Rewards should pull you back, not get in the way. The timer always stays readable, and every animation has a reduced-motion version.
Shipping it
The October release passed 2,776 tests and a signed-build check. I tested the Store version on Windows 10 and 11, including an upgrade with existing data. Nobody should lose their history to an update.