From a posted wish to a shipped app: Shuffle Timer

The wish

The idea was asked for by an exerciser on r/SomebodyMakeThis, and it reached the board on 17 October 2026 as idea #0020. In short: you type in your exercises (jog, walk, sprint), a set of possible durations, a rest time and a number of rounds, and the timer picks each round at random. The point is to keep interval training unpredictable without planning every block, with a sound or a vibration to tell you when to switch.

What the build started from

On 20 October the steward asked the project's owner for a labelled “house builder” account, so it could ship small apps from ideas on the board and show the loop working while the shipped page was empty. The owner said yes: the code would be open source, and each README must say up front that the project is 100% AI-generated and link to the idea. The steward picked this idea first because it could be a static app that works offline and saves to the device.

There was no brief yet. The build started from the idea's own words and those conditions. Later that same day the site began adding weekend plans to selected ideas, and this one got its own: four things in scope (set up a workout, pick each round at random with a big countdown, cue each switch with sound and vibration, keep the screen awake and save workouts on the device), plus two optional ones (show what's coming next, work offline). It ends with a prompt you can copy into an AI coding tool. Both are on the idea page now, for the next builder.

What got built, and what was left out

Shuffle Timer is a phone-first web app. You type exercises one per line. Lengths can be a list (30, 45, 60), a range (20-90) or a mix, and rest works the same way. It estimates how long the workout will take, saves exercise lists by name, and avoids picking the same exercise twice in a row when there's a choice. During a workout the screen changes color between work and rest, beeps for the last three seconds, vibrates where the phone supports it, and stays on where the browser allows. It works offline once installed. Space pauses, N skips and Esc ends.

Left out on purpose: accounts, a server, tracking, analytics and third-party scripts. Everything stays on your device. It is a static site with no secrets, so the code could be public under the MIT license.

What review caught

The first commit landed at 01:04 UTC on 20 October. Before anything went on the board, a second AI agent (Codex) reviewed the app's code. Round one asked for four fixes:

• The offline copy of the app could be replaced by an error page. Now only a good response for the app itself refreshes it, with tests for 404s, 500s and reloading offline.
• The page could get wider than a 375px phone screen. The clock now shrinks for longer times, and long text can no longer push the layout wider.
• The timer needed accessibility fixes. The countdown now has a spoken label for screen readers, and pausing reads out the time left.
• The finish screen reported the plan, not what you did. It now shows the time you actually spent and marks skipped rounds.

The fix commit also stopped skip from jumping a segment, and toned down the README's wording about randomness so it didn't overpromise. Round two approved it with no findings. Review of the record that puts the build on the board caught one more thing: the README didn't invite anyone else to build the idea. It does now.

How it shipped

The build went on the board on 20 October, three days after the idea was posted. It has its own credit page, with a screenshot, a link to the app and its code, and the line “asked for by an exerciser on r/SomebodyMakeThis”. It is labelled as a house build everywhere it shows. It still counts in the public totals, like “1 shipped” on the idea, but the site's own measure of progress counts only builds by people other than the steward. The app's README carries a “Built from an idea on Somebody Build This” badge that links back to the idea, and the idea page lists the build. The idea stays open: ideas here never lock, and anyone can ship their own version next to this one.

Your turn

Each of these ideas has a weekend plan and a prompt to copy on its page:

• A recipe saver that strips the life story and gives you just the recipe
• A lock-screen countdown that shows teachers how long is left in the period
• A knitting pattern viewer that remembers your row, repeat and notes

Or browse project ideas real people asked for. When yours works, ship it on the idea's page and it gets a credit page of its own.