Your Last.fm or Spotify history as a timeline of eras: the albums and artists that ran each stretch of your listening.
Static, browser-only. https://eras.matranc.com
Spotify listeners upload their Extended streaming history ZIP in the page. It is parsed in the browser and never uploaded; plays are song streams of 30 seconds or more, and podcasts, audiobooks and videos are ignored.
echo 'window.LASTFM_KEY = "your-key";' > src/config.js # gitignored
cd src && python3 -m http.server 8642Open http://localhost:8642. Test the era logic and the source adapters with node test.js.
Pushing to main deploys src/ to GitHub Pages. One-time setup: add a repo secret LASTFM_API_KEY, and set Settings → Pages → Source to "GitHub Actions".
The key never lands in a git branch. It's still visible in the live site's network requests, as with any browser-only app.