Fuel

what it is

A mobile-first fitness tracker, installable to your phone like an app, for logging food, weight, and workouts. Pick a goal and the Today tab shows your calorie, macro, and fibre rings against what you have eaten. Log food three ways: scan a barcode, search Open Food Facts, or photograph the meal and let a vision model estimate what is on the plate, which is the path that covers home cooking and anything without a label. A Train tab runs a push, pull, and legs split and shows your last session for each lift so you can beat it. It tracks and visualises; you set the targets, not a coach.

what is unique

It is a real product, not a personal script. Full multi-user cloud sync on Supabase, with row-level security so each person only sees their own data, yet it still works completely offline. The photo estimate is treated as a starting point rather than an answer: it lands in an editable entry you confirm before it is saved, because a vision model guessing at portion size is genuinely uncertain and a number that silently saves itself is worse than one you were asked to check. And every target is transparent and editable, not a black box: the calorie and macro numbers use standard sports-science formulas, each shown with its source. That is what took it from a weekend build to something real testers open every day.

how it was built

The whole app is a single 79KB index.html of vanilla JavaScript, no framework and no build step. Supabase was added later as a purely additive backend over an already-working offline app, so sync is a bonus, never a dependency. Nutrition data is free from Open Food Facts. It installs to a phone through a web manifest and service worker. Built almost entirely through conversational development with Claude, by an MBA with no engineering background, which is the point.

from the live build

01 / 04

Four ways in, because friction is why food tracking gets abandoned. Photo, barcode, search, or a saved meal, with the day still empty underneath.

02 / 04

The training half of the same app: the session plan for the day, and sets logged weight by reps as they happen.

03 / 04

Search runs against the Open Food Facts corpus, so real supermarket products come back with real per-100g numbers.

04 / 04

The day once a meal has landed: calories left against target, the four macros underneath, weight and steps below that.