JAVASCRIPT + HTML · ANDROID & IPHONE

Your pace. Your progress.

I want to count workout sets and get an alert when rest is over.

Count completed sets, start a 30-second rest and stop it. The remaining time is calculated from a saved deadline, so reopening does not restart it.

Download the app · HTML Download · JavaScript (.js)Get the AI prompt

What Kapsula adds

The Kapsula bridge schedules an OS notification and stores the deadline. Delivery and sound depend on notification permissions and device settings; JavaScript does not run continuously in the background.

Try it on your phone

Install Kapsula from Google Play / App Store.
Download the HTML or .js above, tap Add project and select the file. When pasting, choose the matching format: HTML or JavaScript (.js).
Tap Run. Try the actions and reopen the project to check its saved state.

No Kapsula account, developer membership or separate project build. Your projects need Pro: a 7-day trial, then a subscription or lifetime purchase. The built-in demo is free.

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Interactive web preview. Native notifications are tested in Kapsula.

Ask AI to write your own version

Build a workout set counter and a 30-second rest timer. Save the counter and absolute deadline, schedule one notification, support Stop, handle permission errors and prevent duplicate starts.

Return ONE complete HTML file for Kapsula (https://kapsula.app/), with inline CSS and JavaScript, a descriptive title, no external dependencies, imports, server or Markdown fences.
Use const K = window.kapsula || null; in Kapsula await K.ready.
Save project data using await K.storage.get(key) and await K.storage.set(key, value), never localStorage in Kapsula. Preserve existing data when updating code.
Supported native bridge: app.info, storage.get/set/remove, notify.schedule/cancel/list, sound.play while open, haptics.vibrate. Do not invent camera, network or location APIs.
If using a timer, store an absolute deadline. Schedule with await K.notify.schedule({at: epochMs, title, body}) -> {id}; allow at most 16 pending notifications. Cancel with await K.notify.cancel(id). Handle errors, prevent duplicate starts and cancel a late scheduled result if needed. Browser setTimeout is not a native notification.
Use an explicit browser-preview fallback and label it: no native background notifications. Do not promise delivery after Android force-stop.
Make the UI beautiful, mobile-friendly, accessible and self-contained.

Your code defines the design

Ask your AI to add exercise names or change the rest duration. Keep cancellation, stored deadlines and error handling.

Open Update code in project settings: the saved source is already in the editor. Edit it and run the update for this project. If code fails, use Copy the error for your AI, then send the error and source to your assistant yourself.

JavaScript (.js) guide and prompt →

Format and compatibility

The JavaScript file and saved-source editor require Kapsula 0.4.0. The HTML version remains compatible with 0.3.0. Both formats use the same project data and API with no external dependencies. Update the existing project to keep its records; a new project has separate storage. The web preview demonstrates the UI and actions, not notification delivery on a locked phone. For the timer, check permissions and test a short alert on your device.

Bridge API · General prompt · Verified notification walkthrough · Privacy