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APPS 100

100 Apps Challenge

Build small apps for my own use, and release only the ones people ask for. Starting with Apple Watch, moving on to web apps that live on the phone's home screen. A challenge to make 100.

Video captions are in Japanese.

  1. No.01Apple Watch

    Seminar Timer

    The problem
    Checking the clock on stage breaks your flow. What you want to know isn't "how many minutes left" but "where am I in the talk".
    What I built
    Shows only your progress, with taps on the wrist: once every 10 minutes, twice at the halfway mark, three times at the end.
    What I learned
    Keeping the screen up with a workout session gets rejected in App Review unless the app is for fitness. WKExtendedRuntimeSession (the mindfulness type) keeps it in front instead.

    View on Instagram

  2. No.02Apple Watch

    Sunset Countdown

    The problem
    At a campsite you lose track of time and suddenly it's dark. Pitching the tent and lighting the fire should happen before sunset.
    What I built
    Shows the time left until sunset and notifies you 60 minutes before, 30 minutes before, and at sunset. A watch-face complication shows the countdown too.
    What I learned
    Handing a complication three hours of minute-by-minute timeline entries at once made it fail to load. Sending one hour at a time fixed it.

    View on Instagram

  3. No.03Web app (PWA)

    Chore Points

    The problem
    Paper doesn't let you improve — and not only in business. A paper chore chart never shows a child how many points they have, or what is actually working.
    What I built
    The same loop we use in business, brought home: the child requests, the parent approves with a stamp, a gauge shows progress to the goal, the app proposes a target at a 70–80% success rate, and month-over-month analysis shows what's working. Decide, target, analyze, act — as a family.
    What I learned
    Before building a home-screen web app (PWA), I had AI list the known traps first: logins not shared between the home-screen app and Safari, stale caches blocking updates. Bugs you are guaranteed to hit unprepared were all avoided up front.

    View on Instagram

  4. No.04Web app (PWA)

    Daily Practice Notebook

    The problem
    "Compare yourself with who you were yesterday, not with the person next to you." But you can't compare with a yesterday you can't see. I thought I was keeping up my daily practice, and honestly didn't know whether I was.
    What I built
    In the morning, pick one practice for today. At night, record whether you did it. That's the whole app. Only three numbers: a running total that never goes down, the current streak, and the difference from a month ago. No rankings, no scores.
    What I learned
    Seeding three starter practices on first open ran twice because the page rendered twice, inserting duplicates. A unique constraint in the database ("one row per name") fixed it. Invisible double execution is better guarded by constraints than by code.

    View on Instagram

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