Comparison with other libraries
How this library compares to other file transfer options in the React Native ecosystem:
| Capability | This library | expo-file-system | react-native-blob-util | react-native-fs |
|---|---|---|---|---|
| Background downloads on iOS | ✅ | ✅ 1 | ❌ | ✅ 4 |
| Background downloads on Android | ✅ | ❌ 2 | ⚠️ 3 | ❌ |
| Background uploads | ✅ iOS + Android | ⚠️ iOS only | ❌ | ❌ |
| Reconnect to transfers after app restart | ✅ | ❌ 2 | ❌ | ❌ |
| Pause / resume | ✅ iOS + Android | ⚠️ iOS only | ❌ | ⚠️ iOS only 5 |
| Progress events | ✅ | ✅ | ✅ | ✅ |
| Expo config plugin | ✅ | built in | ❌ | ❌ |
| New Architecture (TurboModules) | ✅ | ✅ | ✅ | ⚠️ via community fork |
| General filesystem API | ❌ | ✅ | ✅ | ✅ |
1 Via sessionType: 'background' (iOS only).
2 From the Expo docs: "Android accepts this option for API consistency and ignores it", and "the JavaScript DownloadTask instance is not restored if the app is terminated or relaunched, so its promise, progress callbacks, and cancellation state are only available while the original JS runtime is still alive."
3 Via useDownloadManager: true, which is GET-only and can only write to external storage.
4 Via the background: true option (iOS only).
5 Via the resumable callback (iOS only).
The key difference is the highlighted row. Several libraries can hand a transfer to the OS. This is the one that can find those transfers again after your app has been killed and relaunched - getExistingDownloadTasks() returns live task objects you can re-bind your UI to, on both platforms.
When you probably don't need this library: if your files are small, or a failed transfer can simply be restarted from zero next time the user opens the app, expo-file-system is simpler and already in your project. Reach for this one when a transfer is long enough that losing it costs the user real time.