Webhook Reliability

Meta's webhook delivery system is designed for reliability — which means it retries failed deliveries. Your server must follow three rules to handle this correctly.

Rule 1 — Send 200 immediately, process after#

Meta expects a 200 response within a few seconds. If it doesn't get one, it retries the same event — which means your bot processes the same message twice.

app.post('/webhook', (req, res) => {
  res.sendStatus(200);          // ← FIRST — before any logic

  const message = changes.messages[0];
  // process here, after 200 is sent
});

Rule 2 — Deduplicate by message ID#

Because Meta retries, the same message can arrive twice with the same id. Store seen IDs and skip duplicates:

const seen = new Set(); // use a database in production

if (seen.has(message.id)) return; // already processed
seen.add(message.id);

// now process safely

Rule 3 — Don't trust order#

If a customer sends "Hi", "How are you?", "Hello?" quickly, Meta does not guarantee they arrive in order. If order matters, sort by the message timestamp:

const timestamp = parseInt(message.timestamp); // unix timestamp

Frequently asked#

Gotchas & common mistakes#