Webhook
Last Updated: July 29, 2026 | By Mihail Sebastian | AI Dictionary
An HTTP callback that pushes data to a receiving URL the moment an event happens, so services learn about training runs or payments without polling.
What is a Webhook?
A webhook is an HTTP callback: when an event happens in one system, it immediately sends the details to a URL that another system provides. The receiver gets the data pushed to it at the moment of the event instead of repeatedly asking whether anything changed.
Polling wastes requests and adds delay. A webhook costs one request, exactly when it matters.
How Webhooks Work
The receiving service exposes an endpoint URL and registers it with the sender. When the event fires (a training job finishes, a payment clears, code is pushed), the sender issues an HTTP POST to that URL with a JSON payload describing what happened.
The receiver verifies the request is genuine, usually by checking a shared-secret signature in the headers, then acts on it. If the endpoint is down, most senders retry with backoff.
The pattern is everywhere in developer infrastructure. GitHub fires webhooks on every push to start CI builds, payment providers fire them when charges settle, and ML platforms fire them as jobs change state.
Example of a Webhook
An ML team runs training jobs that take hours. Instead of watching a dashboard, they register a webhook endpoint with their training platform.
When a job completes, the platform POSTs a JSON payload (job ID, final metrics, model location) to that endpoint. The endpoint, a small serverless function, posts the metrics to the team’s chat channel and, if evaluation clears the threshold, triggers the pipeline that packages the model for deployment.
Nobody polls anything. The finished job announces itself.
Related AI terms: JSON · Lambda Function · Pipeline · Deploy
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Mihail Sebastian — Writes about AI governance, regulation, and the technology behind them. Placeholder bio — replace with a real credential line. About