Webhook delivery with retries sequence diagram template

Participants in this sequence diagram

• Platform
• Event queue
• Webhook worker
• Receiver endpoint
• Dead-letter queue

How to use this sequence diagram template

1. Click Open in the editor. The sequence diagram opens on a new page in FlowDiagram — nothing is uploaded and there is no sign-up.
2. Rename, add or delete shapes and drag them where you want; connectors stay attached as things move.
3. Drop in vendor logos from the library — 1,160 of them, including every AWS, Azure and Google Cloud service icon — or restyle it with the colour and theme controls.
4. Prefer text? Edit the Mermaid source below and paste it in through ☰ → Import diagram (see the Mermaid editor); it imports as an editable diagram.
5. Export to PNG, SVG or PDF, or press Ctrl+L for a link that carries the whole diagram.

Mermaid source

The whole template is the text below. Paste it into FlowDiagram, keep it in Git next to the code it describes, or hand it to an AI assistant to extend.

sequenceDiagram
  autonumber
  participant App as Platform
  participant Q as Event queue
  participant W as Webhook worker
  participant R as Receiver endpoint
  participant DLQ as Dead-letter queue
  App->>Q: Publish invoice.paid event
  Q->>W: Deliver event
  W->>W: Sign payload (HMAC-SHA256)
  loop Up to 5 attempts, exponential backoff
    W->>R: POST /webhooks + signature header
    alt 2xx response
      R-->>W: 200 OK
    else Timeout or 5xx
      R-->>W: 503 Service Unavailable
      W->>W: Wait 2^n seconds and retry
    end
  end
  opt All attempts failed
    W->>DLQ: Park event for replay
    W->>App: Mark endpoint unhealthy
  end
  W->>Q: Ack message
  Note right of R: Receiver must verify signature and be idempotent

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