Vitals
A free single-file health tracker and coach.
The problem
Daily health numbers lived apart from the goals they were meant to serve. The tool needed to turn plain-language goals into weekly targets, then adjust those targets from actual recent data instead of treating one rough week as failure.
What it does
A personal health tracker with a coaching layer, built as a single file so there is nothing to install, host, or pay for. Built for one user first — me — which is the filter every tool here has to pass before it becomes a product.
Currently pointed at a steady, safe weight-loss goal.
Why it is built this way
I made it a self-contained browser ledger with no account: health data stays in local storage on the device, and phone/watch history can be imported. The coach starts from a real 14-day average, stretches weight loss to roughly 0.5 kg per week when needed, and holds targets after a week with fewer than three goal-days instead of escalating them.
What was hard
Everything ships in one HTML file with no server, no build and no account, so state, charts and the coaching logic all live in the same document and persist to local storage. That constraint is the point - it opens from a file on any machine - but it leaves nowhere to hide complexity.
Outcomes
- Zero install
- Zero hosting cost
- Daily use