How to fix Firestore: Daily read quota exceeded (50,000 reads/day on free tier) in Firebase

Open Firebase Console → Firestore → Usage & billing and switch the chart to Document reads with the last 24‑hour window. If the line hits 50,000 and the count stops growing, the Spark plan quota is exhausted. Also inspect Project settings → Usage and billing to confirm the project is still on the Spark (free) tier, which includes exactly one Firestore database and 50,000 reads/day (see https://firebase.google.com/docs/firestore/quotas).

In Firebase Console → Usage & billing → Manage plan, switch from Spark to Blaze and attach a Cloud Billing account. Blaze removes the 50,000/day free cap and charges per Firestore read (e.g., $0.06 per 100k reads in the U.S.), so you can serve more traffic without ResourceExhausted errors. After upgrading, create budgets/alerts in Cloud Billing so you get notified before the spend exceeds your comfort level.

For repeated reads (feature flags, config, dashboards), store the last value in memory and only refetch when it expires. Example in JavaScript:

const cache = new Map<string, { data: DocumentData; expiresAt: number }>();

async function getCachedDoc(path: string) {
  const entry = cache.get(path);
  if (entry && entry.expiresAt > Date.now()) {
    return entry.data;
  }

  const snapshot = await getDoc(doc(db, path));
  const data = snapshot.data() || {};
  cache.set(path, { data, expiresAt: Date.now() + 60_000 }); // 60s TTL
  return data;
}

Also enable IndexedDB persistence (call enableIndexedDbPersistence() on web clients or disk persistence on mobile) so Firestore automatically serves cached data and reduces network reads.

Instead of fetching an entire collection, store pre-aggregated documents that contain the values your UI or function needs and update those summaries via Cloud Functions:

exports.refreshDailyTotals = functions.firestore
  .document('orders/{orderId}')
  .onWrite(async (change, context) => {
    const db = admin.firestore();
    const summaryRef = db.doc('materialized/dailyTotals');
    await db.runTransaction(async (tx) => {
      const summary = (await tx.get(summaryRef)).data() || { reads: 0 };
      const delta = (change.after.exists ? change.after.get('amount') : 0) - (change.before.exists ? change.before.get('amount') : 0);
      tx.set(summaryRef, { reads: summary.reads + delta }, { merge: true });
    });
  });

Also use select(), limit(), and where() filters that keep the number of matched documents low.

Create a Cloud Monitoring alert on the metric firestore.googleapis.com/document/read_count and set the threshold at ~45,000 reads for a rolling 24-hour window. Configure notifications (email, Slack, etc.) so your team can throttle traffic before Firestore responds with the quota error. You can also export Firestore usage to BigQuery or use the Firebase Usage page to look at top collections and Cloud Functions that consume reads.