Webhook
Noun · Development · Origin: 2007
Definitions
A webhook is an HTTP callback mechanism that allows one system to send real-time notifications to another when a specific event occurs. Instead of the receiving system repeatedly polling an API for updates, the source pushes data to a pre-configured URL as soon as the event happens. For example, Stripe sends a webhook when a payment succeeds, GitHub sends one when a pull request is merged, and Slack sends one when a message is posted. Payloads are typically JSON over HTTPS POST requests. Implementing webhooks requires handling retries (since HTTP calls can fail), verifying signatures to prevent spoofing, and processing events idempotently so duplicate deliveries do not cause duplicate side effects. Webhooks are the foundation of event-driven integrations between SaaS platforms.
In plain English: A way for one application to automatically notify another when something happens — like setting up a doorbell instead of checking the door every five minutes.
Etymology
- 2007
- Jeff Lindsay coins the term 'webhook' as a user-defined HTTP callback — the web equivalent of a Unix pipe
- 2010s
- GitHub, Stripe, and Slack integrate webhooks, making them the standard pattern for real-time event notification between services
- 2020s
- Webhook reliability becomes a discipline — retry logic, dead-letter queues, and signature verification become best practices
Origin Story
The web's version of 'don't call us, we'll call you'
A **webhook** is an HTTP callback: a URL that receives data when an event occurs, inverting the traditional request/response pattern. Instead of repeatedly polling an API to check for changes, you register a webhook URL and the service pushes updates to you. The term was coined by **Jeff Lindsay** in 2007 on his blog.
Lindsay's insight was that webhooks turned any web application into a programmable platform. He wrote: "Webhooks are user-defined HTTP callbacks. They are triggered by some event, such as pushing code to a repository or a comment being posted to a blog. When that event occurs, the source site makes an HTTP request to the URI configured for the webhook."
The pattern existed before the name — PayPal's Instant Payment Notification (IPN) was essentially a webhook. But Lindsay's naming crystallized the concept and made it a standard architectural pattern. Today, webhooks are used by GitHub, Stripe, Slack, Twilio, and virtually every SaaS platform. They're the event-driven web's equivalent of "don't call us, we'll call you."
Coined by: Jeff Lindsay
Context: Jeff Lindsay's blog, 2007
Fun fact: The biggest challenge with webhooks isn't sending them — it's receiving them reliably. If your server is down when a webhook fires, you miss the event. This spawned an entire category of 'webhook relay' services and the practice of implementing idempotent webhook handlers.