Slim Chance

Better odds than the name suggests.

Slim Chance is a calm weight-loss app for people doing it on their own. It measures you against yourself: a trend instead of the daily scale, a week of food instead of a perfect day, and a plan for the moments that undo most diets (the evening, the Friday, the weekend), handed to you when you pick up your phone rather than on a clock. No streaks, no guilt, no red.

The name is the joke; the odds are real. A coin landing on its edge is the textbook slim chance (it's the mark), and every morning the app tells you yours: the odds in ten that your weight is really coming off. It was called Moderly until 30 October 2026.

Get it: Slim Chance is an iPhone and Android app, on its way to the App Store and Google Play. Until then, open slimchance.app to start, or install the Android app from Releases. No account needed to start. How it works: slimchance.app/about.

Made-up data. More at slimchance.app/about.

What it does

• Your trend, not today's number. One line through your morning weigh-ins, with how sure it is, as odds in ten. Set a next stop and the app says what it means, for example leaving a BMI band, and only calls it reached when the trend stays there.
• A week of food, learned from your own log. Log the way you do; rough is fine. The week's budget comes from your log and your scale together, so whatever the log leaves out (oil, a handful of nuts) cancels out. Search, barcodes, or a photo with an AI estimate.
• Keep it off. At the goal, Slim Chance asks to keep it there or aim lower. Keeping it, the budget is your maintenance, a ceiling sits a kilo above, and Today counts the days the trend stayed inside that range (a rate, never a streak). Over the ceiling, your own plan comes back with one gentle step down.
• When the scale jumps, it says why, from your own log: a bigger day, the weekend, a first workout after a break, or nothing it can see.
• Period-aware weight, if you want it: mark the first day of each period; after three cycles Slim Chance learns your own water swing and explains those mornings.
• Plans for the hard moments. Write what you'll do on a Friday night or a late evening; the evening notification hands it back at that moment, with a line from Epictetus or Marcus Aurelius.
• A morning briefing at your first unlock. The weather where you are, the day's session and food, and buttons to log your weight from the notification (Android).
• Training that respects your body. Your own weekly plan, or a guided six-week return after a back injury, paced by how it feels each morning.
• Health Connect on Android: steps, sleep and workouts from your watch.
• For anyone: start without an account and save it later; kilograms, pounds or stone; a walking week if you don't go to a gym. For adults (18+).
• Bring your history: import weigh-ins from Apple Health, Libra, Happy Scale, MyFitnessPal, Withings, Fitbit, Google Fit, Samsung Health or any CSV, so the trend starts on day one. Read on the device; one reading a day; undoable.

Principles

• Measured against yourself, never against an average person's day.
• Honest numbers: a trend with its uncertainty; nothing invented.
• Quiet by default: a notification only when it is true and useful; never an alarm.
• No streaks to lose, and never red for a bad week.
• Your data is yours.

Privacy

• Your data lives in a Supabase (Postgres) database. Row-level security means each account can read and change only its own rows.
• No ads, no third-party trackers, no data sold.
• AI is used only when you ask for it (an estimate from a photo or a description, a recipe). It goes to Google Gemini; words (never photos) may go to free fallback providers when Gemini is busy. Body-fat estimates from photos stay off until the key is on Gemini's paid tier (set the GEMINI_TIER=paid secret), because on the free tier Google may read what is sent.
• Trials (no email yet) unused for 30 days are deleted, nightly.
• Export everything at any time: Settings → Export my data.

Run your own

Slim Chance is a SvelteKit (Svelte 5) app with a Supabase backend, shipped to Android as a thin Capacitor shell that loads the web app.

You need Node 24 or newer, a Supabase project and the Supabase CLI.

1. git clone https://github.com/slimchanceapp/slimchance && cd slimchance/svelte-recomp && npm install
2. Copy .env.example to .env and fill in your project's URL and publishable key.
3. Apply the SQL files in supabase/migrations/ to your project, in order.
4. Deploy the edge functions in supabase/functions/. Optional secrets: GEMINI_API_KEY (the free fallbacks work without it), and for web push VAPID_PUBLIC_KEY, VAPID_PRIVATE_KEY and VAPID_SUBJECT.
5. npm run dev. Before any commit, run npm run verify: the self-check suite, the type check and the build.

Setting up from scratch hasn't been tested end to end yet. If a step fails, please open an issue.

Repository

• svelte-recomp/ is the app (the folder keeps the project's first name). Most of the logic in src/lib is pure and tested by scripts/selfcheck.js.
• supabase/ holds the migrations and the edge functions.
• svelte-recomp/android/ is the Capacitor Android shell and its native plugins.

License

AGPL-3.0. You can use, study, change and share Slim Chance; if you run a changed version for other people, share your changes too. The fonts are under the SIL Open Font License (svelte-recomp/static/fonts/OFL.txt); the exercise photos come from free-exercise-db (public domain).