Webhooks vs Polling: The Decision Most Teams Get Backwards
The polling versus webhooks decision is frequently made on the basis of what the API provider finds easiest to implement rather than what serves consumers best. Polling is easier to provide — it requires no additional infrastructure beyond the existing API endpoints. Webhooks require the provider to maintain delivery infrastructure, handle failures, implement retry logic, and manage consumer endpoint registration. The provider’s preference for polling is understandable. For the consumers who pay the operational cost of polling, it is not a neutral choice.
Polling means making repeated requests to check whether something has changed. A consumer that needs to know when an order status changes polls the order status endpoint every N seconds, processes each response to detect changes, and discards the responses where nothing has changed. At low polling frequencies, there is an inherent latency between when the state changes and when the consumer detects it. At high polling frequencies, the consumer makes many unnecessary requests and the provider receives traffic that provides no signal value.
The Operational Cost of Polling
The costs of polling are distributed and therefore invisible at the individual request level but visible at the system level. A consumer polling 1,000 resources every 30 seconds generates 120,000 requests per hour, the overwhelming majority of which return unchanged state. The provider’s infrastructure handles this traffic. The consumer’s infrastructure generates it. Neither party has made an explicit decision that this volume of unnecessary requests is an acceptable operating cost — it emerged from a default that was not examined.
For the provider, polling traffic can dwarf event-driven traffic by orders of magnitude. A webhook delivery system that delivers 1,000 events per hour is equivalent from a consumer data perspective to a polling system that generates 120,000 requests per hour to check 1,000 resources. The infrastructure cost difference favors webhooks significantly.
For the consumer, polling requires maintaining scheduler infrastructure, implementing change detection logic, handling the edge cases where a polling response contains multiple changes, and managing the latency between event occurrence and detection. None of this is difficult. All of it is unnecessary if webhooks are available.
Webhook Implementation Requirements
Webhooks require the consumer to operate an HTTP endpoint that receives event deliveries. This requirement is the primary argument for polling in environments where the consumer cannot expose a public endpoint — behind a corporate firewall, in a development environment without a public IP, in a batch processing context that does not maintain a persistent server.
The requirement is genuine and the tooling ecosystem that has grown up to address it — ngrok for development, services like Hookdeck and Svix for webhook management — reduces the friction for the cases where it is not. The cases where a consumer genuinely cannot operate a webhook endpoint are narrower than the cases where a consumer defaults to polling because polling is familiar.
The provider’s webhook implementation must address reliability. An event that is delivered once and not acknowledged by the consumer due to transient failure must be retried. The retry policy — exponential backoff, maximum retry count, dead letter handling for events that cannot be delivered — determines whether webhooks are operationally reliable or operationally surprising. Consumers should be able to observe delivery attempts and failures.
Idempotency is the requirement that most webhook implementations handle incorrectly. The consumer endpoint will receive duplicate deliveries — at-least-once delivery is the practical guarantee for any reliable webhook system. The consumer must handle this correctly, either by processing duplicate events idempotently or by tracking event IDs to detect and discard duplicates. An endpoint that processes payment webhooks without idempotency handling will process payments multiple times when retries occur.
When Polling Is Appropriate
Polling is appropriate when the consumer needs historical data rather than real-time events — checking the state of a resource as of a particular point in time. It is appropriate when the consumer’s processing model is inherently batch-oriented and the latency of periodic polling matches the processing cadence. It is appropriate when the events are so infrequent that the overhead of maintaining webhook infrastructure is disproportionate to the volume.
The default should be webhooks for real-time event notification, with polling as a fallback for environments where webhook receipt is not feasible. Providers who implement only polling because it is easier to build are making a decision that compounds across every consumer integration for the lifetime of the API. The right infrastructure investment is the one that serves consumers rather than the one that minimizes provider implementation effort.