The Pokepedia Pokedex tracker works offline after you cache it once with the Make offline button. A service worker stores the tracker page, its JavaScript, and every default Pokemon sprite so you can mark catches with no internet connection.
Step 1
Open /pokedex-tracker once while online. In the red header band look for the Make offline button next to the tracker subtitle. The button is black with a download icon.
Step 2
Click Make offline. The button becomes a progress indicator that shows percent complete and current sprite count. The one-time download is about 5 MB: the tracker HTML, its Next.js chunks, and all 1,028 default Pokemon sprites.
Step 3
When caching finishes the button changes to a green "Tracker works offline" badge. The service worker has saved the tracker into a cache named pokepedia-tracker-offline-v1 and your browser now serves that cache when it cannot reach the network.
Step 4
Turn off Wi-Fi or open the site in airplane mode. Navigate to /pokedex-tracker. The page loads from the cache with every sprite. Catches, shiny marks, and notes save to localStorage on the device exactly as online. No other Pokepedia page works offline, only the tracker.
Step 5
To free the storage press Clear next to the green badge. That deletes the tracker cache and the sprite files. Your catch data stays in localStorage because that is a separate store. Re-cache any time by pressing Make offline again.