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What is Hook0?

Hook0 is an open-source webhook server (Webhooks as a Service). It receives events from your applications and delivers them to configured webhook endpoints, handling retries, signatures, and monitoring for you.

The problem​

When your application needs to send webhooks, you end up building:

  • Retry logic for when the receiving system is down
  • Queue management for thousands of deliveries
  • Monitoring to track and debug failures
  • Signature generation for authenticity

Hook0 handles all of that so you don't have to.

Before and after Hook0​

Without Hook0​

Problems:

  • Webhook code scattered across your application
  • No centralized visibility on delivery status
  • Retry and failure logic you have to maintain yourself
  • Hard to debug failed deliveries

With Hook0​

What changes:

  • One API call to send events
  • One dashboard for all deliveries
  • Retry logic works out of the box
  • Full visibility and debugging tools

How Hook0 works​

  1. Your application sends events to Hook0 via REST API
  2. Hook0 validates and stores events
  3. Hook0 delivers events to configured webhook endpoints
  4. Failed deliveries are retried on a fixed schedule (3s, 10s, 3min, 30min, 1h, 3h, 5h, 10h)
  5. All attempts are logged and viewable in the dashboard

Core concepts​

Organizations​

The top-level entity. Organizations group users and applications together, providing isolation and access control.

Applications​

Applications represent your services or products within an organization. Each application can define event types and have multiple subscriptions.

Event types​

Event types define what events your application can emit. Examples:

  • user.account.created
  • payment.transaction.completed
  • order.shipment.shipped

Events​

An event is a specific occurrence of an event type, containing:

  • Event type identifier
  • Payload data
  • Metadata
  • Timestamp

Subscriptions​

A subscription defines where and how webhook notifications get delivered:

  • Target webhook URL
  • Which event types to receive
  • Authentication headers
  • Retry configuration

Request attempts​

Hook0 tracks every delivery attempt:

  • Response status codes
  • Response bodies
  • Timestamps
  • Retry attempts

Why Hook0?​

  • Open source (SSPL v1), self-hostable, or use the cloud version
  • Written in Rust, scales horizontally
  • RESTful API with official SDKs for eleven languages
  • Automatic retries, dead letter queues, rate limiting
  • Full delivery visibility in the dashboard

Use cases​

  • SaaS integration: let customers receive webhook notifications from your platform
  • Microservices: decouple services with async webhook delivery
  • Audit and compliance: track all events and their delivery status
  • Third-party integrations: connect to Slack, Discord, or any HTTP endpoint

Next steps​