# What is webhook? Definition and examples · Leadraft

URL: https://leadraft.co/glossary/webhook
Summary: A webhook is an HTTP request one app sends to a URL you choose when something happens, so other systems can react without polling.

Glossary · Technical · Last updated October 31, 2026

# Webhook

A webhook is an HTTP request one app sends to a URL you choose when something happens, so other systems can react without polling.

**Also called:** HTTP callback, Web callback.

Instead of your system asking "anything new?" every few minutes, the source app calls you. When an event happens, such as a search finishing or a new lead arriving, it sends an HTTP POST with a JSON body to your endpoint.

Because anyone can send a request to a public URL, good webhooks are signed. The sender computes an HMAC (RFC 2104) of the payload with a shared secret and puts it in a header; your endpoint recomputes it and rejects anything that doesn't match. Including a timestamp in the signature protects against replays. The Standard Webhooks specification describes a common way to do this.

Design your receiver to be idempotent, because senders retry on failures and you may get the same event twice. Respond quickly with a `2xx` code and do the heavy work in a background job.

In a lead workflow, webhooks connect list building to everything after it: pushing new leads into a CRM, starting an enrichment step, or notifying a sales channel when a monitor finds new businesses.

## Example

When a search completes, a webhook posts to an agency's endpoint. Its server verifies the signature, then adds the new leads to a client's HubSpot and posts a summary in Slack.

## In Leadraft

Leadraft sends signed webhooks, and also connects through Zapier, Google Sheets and JSON feeds, and direct pushes to Instantly, Smartlead, lemlist and HubSpot.

## Sources

1.  1.[IETF, RFC 2104: HMAC: Keyed-Hashing for Message Authentication](https://www.rfc-editor.org/rfc/rfc2104)
2.  2.[Standard Webhooks, specification](https://www.standardwebhooks.com/)

## Related terms

-   [Model Context ProtocolThe Model Context Protocol (MCP) is an open standard that lets AI assistants like Claude and ChatGPT connect to external tools and data sources.](https://leadraft.co/glossary/model-context-protocol)
-   [Lead listA lead list is a set of businesses or people you plan to contact, with the fields needed to qualify them and reach them, such as email and phone.](https://leadraft.co/glossary/lead-list)
-   [Lead enrichmentLead enrichment is adding missing data to a lead, such as emails, social links, categories or ratings, so it can be qualified and contacted.](https://leadraft.co/glossary/lead-enrichment)

## Further reading

-   [Integrations](https://leadraft.co/product/integrations)
-   [REST API](https://leadraft.co/docs/api)

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Last built: 2026-11-09