Storage & Offline

Brewser apps can store data locally and keep it across launches. Two standard APIs are backed by real, persistent storage on the SD card.

What works

• localStorage behaves as usual — synchronous key/value, ideal for settings and small state.
• IndexedDB covers the everyday surface: databases and versioning, object stores, and put/add/get/delete/clear/count/getAll/getAllKeys. Advanced pieces — cursors, IDBKeyRange, indexes, and auto-increment keys — aren't implemented, so stick to explicit keys and read whole stores rather than cursoring.

Where it lives, and how long

Storage is written to JSON files under Brewser's folder on the SD card (sdmc:/switch/brewser/…). It's loaded at startup and persists across app launches and across Brewser self-updates — an update swaps Brewser's program files but never touches your storage.

There's no quota beyond the physical space on your SD card — you won't hit a QuotaExceededError, but be a considerate citizen with how much you write.

Isolation: prefix your keys

Storage is shared across apps, not sandboxed per app. All apps on a profile read and write the same localStorage and IndexedDB namespace. Two apps that both use a key called settings, or a database called save, will collide. Namespace everything with your app id — e.g. com.you.myapp:settings.

The brewser.js SDK does this for you automatically: its save box is keyed by your package id, so apps using the SDK don't step on each other.

Offline

Most Brewser apps are fully self-contained and run with no network at all — once downloaded, they work offline indefinitely. Local storage is always available offline.

For cloud saves, the SDK is local-first: every save writes to local storage instantly and syncs to your account in the background when you're online. Saving never blocks on the network and never fails when you're offline — the upload just happens later.

See it in action

• com.natureglass.spectraplay and com.natureglass.savedemo — use localStorage.
• com.natureglass.2dplatformermicrogame — a Unity title that persists through IndexedDB.

Related

• Saves & Leaderboards — cloud saves on top of local storage.
• brewser.js SDK — automatic per-app key namespacing.
• Networking in Apps.