# Hook0 Documentation > Hook0 sends webhooks on your behalf: one API call per event, HMAC signatures, retries with a dead letter queue, delivery logs, and a subscriber portal your customers manage themselves. Open-source (SSPL-1.0) — self-host it, or use the cloud hosted in the EU (France). Every page published here is listed below. ## Hook0 Documentation - [Hook0 Docs — Webhook Server for Reliable Delivery](https://documentation.hook0.com/): Guides, API reference, and architecture docs for Hook0. Self-host or use the cloud — retries, HMAC signatures, and monitoring included. Start sending webhooks in 5 minutes. ## Getting Started - [Hook0 — Open-Source Webhook Server You Actually Own](https://documentation.hook0.com/explanation/what-is-hook0): Self-host or use the managed cloud. Hook0 handles retries, HMAC signatures, and delivery monitoring. Free tier included — no vendor lock-in, full source access. - [Send Your First Webhook in 5 Minutes — Hook0 Quickstart](https://documentation.hook0.com/tutorials/getting-started): From zero to working webhook: create an app, define event types, subscribe an endpoint, and fire a test event. Free tier covers everything — no credit card needed. ## Concepts - [Concepts](https://documentation.hook0.com/concepts/): Core concepts in Hook0 - [Organizations](https://documentation.hook0.com/concepts/organizations): Multi-tenant containers for teams and applications in Hook0 - [Applications](https://documentation.hook0.com/concepts/applications): Logical containers grouping events and subscriptions in Hook0 - [Events](https://documentation.hook0.com/concepts/events): Notifications sent from your applications to Hook0 - [Event Types](https://documentation.hook0.com/concepts/event-types): Categories for webhook events in Hook0 - [Labels](https://documentation.hook0.com/concepts/labels): Key-value pairs for filtering and routing events to subscriptions - [Subscriptions](https://documentation.hook0.com/concepts/subscriptions): Webhook endpoints that receive events from Hook0 - [Request attempts](https://documentation.hook0.com/concepts/request-attempts): Webhook delivery tracking and retry mechanism in Hook0 - [Application secrets](https://documentation.hook0.com/concepts/application-secrets): The API token of a Hook0 application, what it can do, and how it is provisioned - [Service tokens](https://documentation.hook0.com/concepts/service-tokens): API credentials for automated systems and programmatic access to Hook0 - [Metadata](https://documentation.hook0.com/concepts/metadata): Attach arbitrary key-value data to Hook0 objects ## Tutorials - [Tutorials](https://documentation.hook0.com/tutorials/): Step-by-step guides to get you from zero to working webhooks. - [Building your first webhook system with Hook0](https://documentation.hook0.com/tutorials/first-webhook-integration): This tutorial walks through integrating Hook0 into a SaaS platform so your customers can receive webhooks. It uses curl commands throughout, so you can follow along in any language. - [Webhook Events & Subscriptions — Design It Right](https://documentation.hook0.com/tutorials/event-types-subscriptions): Structure events into a type hierarchy, let subscribers filter with wildcards, and route across tenants. The schema design that saves you a migration later. - [Webhook HMAC Verification: the Step Most Integrations Skip](https://documentation.hook0.com/tutorials/webhook-authentication): Working code for Python, Node.js and Go. Covers HMAC-SHA256 signatures, timestamp validation to block replay attacks, and the IP allowlisting gotcha that breaks production. - [Building a Stripe-like webhook system](https://documentation.hook0.com/tutorials/build-stripe-like-webhooks): This tutorial walks through building a production-grade webhook system similar to Stripe's, using Hook0. You will set up event types, a webhook receiver with signature verification, multi-tenancy, an… ## How-to Guides - [How-to Guides](https://documentation.hook0.com/how-to-guides/): Problem-solving guides for specific challenges you'll encounter when working with Hook0 in production. These guides assume you have basic Hook0 knowledge and focus on solving real-world problems. - [Debug Failed Webhooks: Read the Delivery Log, Then Replay](https://documentation.hook0.com/how-to-guides/debug-failed-webhooks): Find out why a webhook failed: read the status code, error name and response body of each attempt, see when Hook0 retries it, then replay the event. - [Webhook Endpoint Security: Why HMAC Beats an IP Allowlist](https://documentation.hook0.com/how-to-guides/secure-webhook-endpoints): Secure a webhook endpoint in five checks: HMAC signature, timestamp window, payload schema, event_id dedup and rate limiting, and why IP allowlists fall short. - [Webhook Monitoring: The 5 Delivery Metrics and the API Fields Behind Them](https://documentation.hook0.com/how-to-guides/monitor-webhook-performance): Success rate, retry rate, error mix, endpoint response time and delivery latency: which Hook0 API field each one comes from, how to compute it, and when to alert. - [Client-side Error Handling Best Practices](https://documentation.hook0.com/how-to-guides/client-error-handling): Implement robust error handling for Hook0 API responses in your applications - [Multi-Tenant Webhook Service: Route Each Tenant With Labels](https://documentation.hook0.com/how-to-guides/multi-tenant-architecture): One Hook0 application for every customer: tag events with a tenant label, filter each tenant's subscriptions on it, and show per-tenant delivery logs. - [Service Tokens: How to Scope Hook0 API Access Down with Attenuation](https://documentation.hook0.com/how-to-guides/manage-service-tokens): Create Hook0 service tokens for CI/CD, scripts, and AI assistants, then attenuate them to least-privilege scope so a leaked token can't touch your whole organization. - [Troubleshooting Guide](https://documentation.hook0.com/how-to-guides/troubleshooting): This guide helps you diagnose and resolve common issues with Hook0. Each section includes symptoms, root causes, solutions, and debug commands. - [Webhook Best Practices: 8 Rules That Prevent Lost and Duplicate Events](https://documentation.hook0.com/how-to-guides/webhook-best-practices): Sign payloads, deduplicate on event_id, answer 200 fast and process async, version event types, use HTTPS: the producer and consumer rules, with Hook0's signature format. ## Reference - [Reference](https://documentation.hook0.com/reference/): Technical specifications for Hook0. Use this reference when you need exact details about APIs, configuration options, data formats, or error codes. - [Hook0 API Reference](https://documentation.hook0.com/openapi/intro): Welcome to the Hook0 API reference documentation. This comprehensive guide provides detailed information about all available API endpoints, request/response formats, and authentication methods. - [Event Payload Schemas](https://documentation.hook0.com/reference/event-schemas): This reference provides standardized schemas and examples for common event types in Hook0. Following these schemas ensures consistency and compatibility across integrations. - [Configuration Reference](https://documentation.hook0.com/reference/configuration):