Running Periodic Background Sync with Expo Task Manager

Insight

Mobile apps often need to stay fresh without user interaction, but many developers assume React Native can’t run reliable background code. Expo’s expo-task-manager (paired with expo-background-fetch) lets you register native‑level tasks that fire even when the app is closed, giving you a true offline‑first sync loop. On iOS the system decides the exact cadence, while Android offers more deterministic intervals via headless JS.

Example

import * as TaskManager from 'expo-task-manager';
import * as BackgroundFetch from 'expo-background-fetch';

const SYNC_TASK = 'background-sync';

TaskManager.defineTask(SYNC_TASK, async () => {
  // Fetch fresh data and store it locally
  await fetchAndPersist();
  return BackgroundFetch.Result.NewData;
});

await BackgroundFetch.registerTaskAsync(SYNC_TASK, {
  minimumInterval: 15 * 60, // 15 minutes
  stopOnTerminate: false,
  startOnBoot: true,
});

Takeaway

Register a single background task and let the OS handle scheduling; keep the task lightweight and idempotent. Remember to request the appropriate permissions and test on real devices, as simulators don’t trigger background fetches.