Webhook
An automated HTTP callback that sends real-time event data from a fleet platform to another system when a specific event occurs — such as a vehicle entering a geofence, a fault code triggering, or a driver completing a trip — enabling instant workflow automation without polling.
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Compare Telematics software →Webhooks vs. Polling: Why It Matters at Fleet Scale
The alternative to webhooks is polling: your system asks the fleet platform 'did anything happen?' every N seconds. At small scale, polling every 30 seconds across 20 vehicles is manageable. At fleet scale — 500 vehicles, 20 event types, polling every 10 seconds — you are making 3,600 API requests per minute, most returning empty responses. This burns API rate limits, adds latency, and creates unnecessary load on both systems. Webhooks invert the relationship: the fleet platform notifies your system instantly when something happens, with zero wasted requests.
Webhook Delivery Reliability: What Can Go Wrong
Webhooks are only as reliable as the receiving endpoint. If your server is down, restarting, or behind a misconfigured firewall when the fleet platform sends an event, that event may be lost. Production webhook implementations must address three failure modes: receiver unavailability (your endpoint is down), receiver timeout (your endpoint is up but responds too slowly — most fleet platforms have a 5–30 second timeout), and duplicate delivery (the platform re-sends on timeout, your system processes the same event twice). The standard solutions are: return HTTP 200 immediately and process asynchronously, implement idempotency keys so duplicate deliveries are deduplicated, and configure the platform's retry policy.
Real-World Example: Instant Customer ETA Notification
A food service distribution company needed to notify restaurant customers 30 minutes before delivery arrival, but their telematics platform only updated ETA estimates in their dispatch system via a scheduled sync every 15 minutes — too coarse for accurate customer notifications. By switching to a webhook on geofence entry events (configuring a circular geofence at the approximate 30-minute-out distance for each regular customer location), their dispatch system receives an event the moment the truck enters the zone. An automated SMS goes out within 45 seconds of geofence entry. Customer complaint calls about missed delivery windows dropped 67% in the first month. The webhook replaced a fragile cron job and eliminated a full-time dispatcher task of manually calling ahead to customers.
- Confirm the fleet platform supports webhooks for the specific events you need — not all platforms expose all event types
- Implement HMAC signature verification on your receiving endpoint to reject forged webhook payloads
- Return HTTP 200 immediately from your endpoint; process the payload asynchronously to avoid timeouts
- Implement idempotency using the event ID in the payload — reprocess detected as duplicates should be discarded
- Set up a dead-letter queue for failed webhook deliveries so no events are permanently lost
- Monitor your webhook endpoint's error rate and response time with an uptime tool
- Test webhook delivery in a staging environment before going to production
- Document retry behavior: how many times will the platform retry on failure, and at what intervals?
Security: Verifying Webhook Authenticity
Anyone who knows your webhook URL can POST fake event data to it. The industry-standard defense is HMAC-SHA256 signature verification: the fleet platform includes a signature header (e.g., X-Samsara-Signature) computed by hashing the payload with a shared secret. Your endpoint recomputes the same hash and rejects any request where the signatures don't match. Never expose a webhook endpoint without signature verification — particularly for events that trigger dispatch actions, payment workflows, or safety alerts, where a spoofed event could cause operational harm.