GPXtoolset
An on-device toolkit for GPX & FIT activity files. Convert, clean, and prepare workouts without ever uploading your data.
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Key Features
- •GPX <-> FIT conversions run entirely in the browser for total privacy.
- •Workspace keeps multiple activities open so you can compare and batch edit.
- •Transformation tools to strip or rebalance metrics before exporting.
- •Timestamp repair and merge timeline helpers for messy device data.
- •Detailed inspectors for parsed metrics plus raw GPX/FIT contents.
- •Poster builder to export a shareable ride summary in seconds.
Development
GPXtoolset is a Next.js SPA backed by TypeScript and Tailwind. The UI is tuned for fast file workflows with optimistic updates and persistent local state.
All parsing, conversions, and poster rendering happen client-side using web workers to keep the interface responsive, paired with structured cloning so large FIT files stay snappy.
Optional Strava import/export routes through lightweight serverless functions that only proxy OAuth - activity files stay on the device for the entire session.
Role & Impact
I designed and built the full product experience: architecture, ergonomics for endurance athletes, and the privacy-first messaging that differentiates it from cloud GPX utilities.
Preview
