CorosLink uses independent data paths — USB for watch files, OpenRouteService for routes, and COROS APIs for training. There is no CorosLink cloud backend.
Music sync
Does not use an official COROS SDK. CorosLink detects your watch when it mounts as a USB drive with a Music folder, then copies MP3 files directly. Every source (YouTube, Spotify, YouTube Music, Apple Music, Apple Podcasts, YouTube Playlists) resolves to an MP3 via yt-dlp + ffmpeg and lands in the local library before transfer.
Map install
Downloads official packages from COROS map servers, caches them locally, and copies them to your watch's map folder over USB. See Map Packages.
Route builder
Calls OpenRouteService to generate a route, then exports GPX for import through the COROS phone app (Bluetooth sync to the watch). Direct cloud upload to your COROS account is not wired up yet. See Route Builder.
Training Hub
Authenticates with COROS team APIs to fetch your analytics, activities, and fitness scores. Credentials are sent to COROS servers at login; all other app data stays on your machine. See Training Hub and Privacy & Data.