Webhook vs API Polling: When to Use Which

The Core Difference

Polling is when your application periodically asks an external API: "Has anything changed?" You make the request on a schedule, check the response, and act on any new data.

Webhooks work the other way around. The external service pushes data to your application the moment something happens. You provide a URL, and the service sends an HTTP request to that URL whenever there is an event.

Think of polling as checking your mailbox every hour, and webhooks as having the mail carrier ring your doorbell on delivery.

Comparison

When to Use Polling

Polling is the right choice when:

• The API does not support webhooks. Many older APIs and government data sources only offer REST endpoints. Polling is your only option.
• Near real-time is not required. If syncing data every 15 minutes or every hour is good enough, polling keeps things simple. No need to expose an endpoint or handle verification challenges.
• Your infrastructure is behind a firewall. Polling only requires outbound HTTP requests. No need to open inbound ports or configure reverse proxies.
• You need guaranteed consistency. Polling lets you fetch the complete current state on each run, which avoids the risk of missed webhook deliveries causing your data to drift out of sync.

When to Use Webhooks

Webhooks are the better choice when:

• You need real-time reactions. Payment confirmations, chat messages, CI/CD triggers — anything where a delay of even a few minutes is unacceptable.
• Events are infrequent. If the data changes once or twice a day, polling every 5 minutes means 99% of requests return nothing useful. A webhook fires only when there is actually something to process.
• You want to reduce API usage. Some APIs have strict rate limits. Webhooks avoid hitting those limits with repeated polling requests that return empty results.

The Hybrid Approach

In practice, many production systems use both. Webhooks handle the real-time flow, and a scheduled polling job runs periodically as a safety net to catch any events that might have been missed due to network issues or webhook delivery failures.

This pattern is sometimes called "webhook with reconciliation." The webhook provides speed, and the polling job provides completeness. For example:

# Real-time: webhook endpoint receives events instantly
POST /api/webhooks/stripe  ->  process payment event

# Safety net: cron job polls every hour for missed events
0 * * * *  GET /api/sync/stripe-reconcile

This gives you the best of both worlds: low latency from webhooks and guaranteed completeness from polling. The polling job checks for any records that the webhook should have delivered but did not.

Implementation Tips

• Make your endpoints idempotent. Whether you use polling or webhooks, your processing logic should handle the same event being delivered multiple times without creating duplicate records.
• Verify webhook signatures. Always validate the HMAC signature or token sent with webhook requests to ensure they come from the expected source, not from a malicious actor.
• Use incremental polling. When polling, track the last sync timestamp and only request records modified after that point. This reduces data transfer and processing time.
• Respond quickly to webhooks. Return a 200 response immediately and process the data asynchronously. Most webhook senders have short timeouts and will retry if they do not get a fast response.