StravaHeatmap connects to your Strava account, fetches your activities, and displays your routes on a real OpenStreetMap map. It also combines all your activities into a single heatmap, allowing you to see which routes you use most frequently. The entire project is self-hosted, meaning your data stays on your own server. Technologies used • ASP.NET Core Web API • Entity Framework Core + SQLite • React + TypeScript • Leaflet + OpenStreetMap • Docker • GitHub Actions One of the most important parts of this project for me was implementing the OAuth 2.0 flow from scratch for the first time. I built the entire flow myself — from generating the authorization URL and exchanging the one-time authorization code for a token, to securely storing the token and automatically refreshing it when it expires. I also implemented the function to decode Strava's encoded polyline data myself. For me, this project was more than just building an application. It was an opportunity to build a real-world, deployable open-source project that others can use and contribute to. 🔗 GitHub: https://github.com/beriltzcn/strava-heatmap You can find more details about the architecture, setup, and implementation in the README.