Fitness Tracker

A lifting tracker built to be better than a spreadsheet: pick or build a programme, log it one-handed while you're mid-set, and see what your training is actually doing to your strength.

▶ Open the live app · works on phone and laptop · no account needed (Account → View demo account to try it with a made-up year of training)

 

 

_{Screenshots use the built-in demo account (invented data).}

Features

• Strength body map — every muscle rated from every exercise that trains it, coloured by where you rank against a comparison group you choose, and faded when there's little evidence. Tap a muscle for its numbers.
• One-thumb logging — each exercise pre-filled with last time's sets, big +/− buttons, 318 built-in exercises, supersets, drop sets and a rest timer.
• Ready-made programmes — nine to start from, each rated for growth, strength, days a week and minutes a session, or build your own.
• Graphs and calendar — strength trends for any lift you've done twice, weekly volume per muscle, and a year-at-a-glance calendar.
• Friends feed — mutual friends only, kudos and comments, compare a lift or a whole body map side by side. No streaks, no leaderboards.
• Goals — pick a muscle and a strength level; it shows what that costs and whether your training is on track.
• Offline and private by default — works with no account and no connection; sign in only to sync between devices. Installs to the iPhone home screen.

Built with

Plain HTML, CSS and JavaScript (ES modules, no build step, no dependencies), a service worker for offline use, and Firebase Auth + Firestore for optional sync. Hosted on GitHub Pages.

---

No build step and no dependencies in the app — plain ES modules and one stylesheet. Serve the folder and it runs.

Use it

Open the live app. On iPhone, tap Share → Add to Home Screen for a real app icon and no browser chrome.

It works fully offline, and it works without an account — sign in only if you want your data on more than one device.

What it does

• Start from a real programme — nine ready-made ones, six credited to the people who published them, each carrying four numbers: how good it is for growth and for strength, and what it costs you in days a week and minutes a session. Or build your own.
• Log while you lift — every exercise pre-filled with what you did last time, adjusted with big +/− buttons sized for one thumb. 318 exercises built in across 16 muscle groups, plus your own when yours isn't listed. Supersets, tri-sets, giant sets, drop sets and myo-reps, with a rest timer that knows the difference.
• Record opens on the next workout in your rotation — it reads your last session, offers the one after it, and says what it read. Every other workout is one tap below it.
• Home is a feed — what the people you train with have been doing: their name, when, the workout, the line they wrote about how it went, a Time · Sets row, and every exercise with its set count. Tap a card to open their whole workout — the muscle split as a share of that session, their bests typed by kind (Weight · Reps · Volume · 1RM), and set tables with the supersets and drop sets intact. From there you can compare a lift against your own, save their workout as one of yours, or share a picture of it. Kudos and comments, no streaks and no leaderboards.
• Body map — every muscle rated from every exercise that trains it, coloured by where you rank among a comparison group you choose, and faded in proportion to how much evidence there actually is. Tap one for the number, the level, and the set it came from. You get a ranking, not a percentile, unless you turn on More details.
• Goals — one muscle, one strength level, twelve weeks. It states what that costs and what your logged training is delivering against it.
• Calendar and graphs — every workout and benchmark on the day you did it, month by month or as one square per day so whole years fit on a single screen; trends for anything you've recorded twice, from workout sets as well as one-off records.
• Friends — mutual only. Find them by name, by your own QR code, or by an invite link.
• One privacy setting for the whole account: private or public. Private means only friends you accept, and they see everything. Public — the default — means anybody signed in who finds you sees it too. Your body weight is the exception and never goes public; it reaches accepted friends only, and only if you switch it on.
• See a friend the way you see yourself — their body map, tappable muscle by muscle with the same panel yours has, under any comparison group you pick; their weekly volume; their graphs. And a Compare button on any muscle map that puts two bodies side by side, one comparison governing both, tapping either opening the same muscle on both.
• A demo account — Account → View demo account fills every screen with a generated year of training so you can judge the app without logging any of it. It never touches storage, and a reload starts it over.

Your data

Signed out, it never leaves your browser. Signed in, it syncs to Firestore so you can open it on another device — see docs/firebase-setup.md. Either way, Settings → Download backup gives you the whole lot as a file, and deleting your account deletes the data with it.

Anybody who can see your account reads a published copy of your training, never your own data — so what is shared is decided when it is written, and the rules decide who may read it. Those are two independent gates and neither is allowed to become the only one.

For developers

Run it locally

It needs a server — ES modules don't load over file://.

python -m http.server 8765
# then open http://127.0.0.1:8765

Tests

node tests/data-layer.test.mjs     # 1855 assertions, no dependencies

# ⚠️ ALL THE TEST-ONLY DEPS IN ONE COMMAND — `--no-save` REPLACES what is
# already installed, so installing them one at a time makes the previous
# suite fail with MODULE_NOT_FOUND.
npm i --no-save jsdom jsqr @firebase/rules-unit-testing
node tests/render.test.mjs

Nineteen suites run headlessly: 4,112 assertions (recounted 2026-09-05 by running every one). Nothing installed here ships with the app.

• Three suites need an npm package, not one: render needs jsdom, qr needs jsqr, rules needs @firebase/rules-unit-testing. The other sixteen need nothing.
• One more suite exists and is not in that 4,112, because it does not run on node alone: tests/rules.test.mjs (175 assertions — the Firestore security rules, run under firebase emulators:exec, and the only tests here that run as somebody who is not you). tests/sw-update.test.mjs (12) IS in the count but needs real Chrome to mean anything.

docs/handbook.md §4 lists every suite and what each one is actually for; progress.md carries what is not verified.

Project layout

index.html              entry point
css/app.css             all styling — mobile-first, desktop in one media query
js/app.js               hash router
js/store.js             data layer (backend-agnostic async API)
js/firebase-backend.js  Firestore + auth adapter
js/exercises.js         the exercise library
js/preset-systems.js    the nine ready-made programmes
js/social.js            friends, private/public, and the published projection
js/feedback.js          a note to the developer — and who the developer is
js/shared-map.js        somebody else's muscle map, in the shape our panel renders
js/ui.js                DOM builder, icons, sheets, steppers, formatters
js/views-*.js           screens
js/body-*.js            the body illustration and its muscle map
tests/                  twenty suites (19 headless + rules) — see Tests above; `node tests/<name>.test.mjs`
tools/                  offline generators and audits, run by hand, never shipped
                        (the body art, the volume colour ramp, the strength fit,
                        the accessibility audit) — read a tool's header before
                        changing anything it generates
docs/                   spec, vision, research, plans, Firebase setup — and the
                        three files below
firestore.rules         who may read whose data — tested by tests/rules.test.mjs

progress.md             project state and the open-work list — the catch-up file
docs/handbook.md        §0–§10: environment traps, working agreement, architecture,
                        design rules, locked decisions. Every "§N" in this project
                        means this file
docs/history.md         the dated session log, newest first — searched, not read
chat.md                 the human-readable log (2026-08-21 onward)
docs/chat-archive.md    the same log, 2026-08-14 to 2026-08-20

⚠️ The four documents split on 2026-09-04, when progress.md reached 626 KB and could no longer be opened in one read. Nothing was rewritten — the dated log moved to docs/history.md and the numbered sections to docs/handbook.md, byte for byte. A session's full write-up now goes to the top of history.md and only its one-line summary to progress.md, which is what keeps that file readable.

store.js exposes an async API, so switching backends touches no screen code.