Webhook Debugging

Webhook Proxy

FastHook webhook proxy mode forwards source traffic to an upstream API and records both sides of the exchange. Use it when you need to see the provider request, upstream response, response body preview, latency, and the routed FastHook event trail in one request trace.

The same source URL model stays in place. A proxy source changes the source response behavior: instead of returning an immediate FastHook acknowledgement, it waits for the upstream API and returns the upstream response to the original caller.

Create proxy sourceRead proxy docs

What FastHook captures

• Inbound request method, path, query, headers, and body.
• Upstream target URL and method.
• Upstream response status, headers, body preview, and truncation state.
• Proxy response latency and fetch errors.
• Routed events, transformations, destination attempts, and retries when connections are active.

Webhook proxy configuration

{
  "name": "production-api-proxy",
  "type": "WEBHOOK",
  "config": {
    "mode": "proxy",
    "allowed_http_methods": ["HEAD", "GET", "POST", "PUT", "PATCH", "DELETE"],
    "proxy": {
      "target_url": "https://api.example.com/webhooks",
      "path_forwarding": true,
      "timeout_ms": 10000,
      "response_capture_limit_bytes": 65536
    }
  }
}

When to use webhook proxy mode

• You need to debug upstream 4xx or 5xx responses without losing provider delivery evidence.
• You want a stable webhook URL that can also forward traffic to an existing API.
• You are migrating from a direct provider webhook URL to a managed webhook gateway.
• You want ngrok-style traffic inspection for deployed webhook traffic, not only localhost traffic.
• You need the same traffic archived to S3/R2, sent to Slack, written to Google Sheets, or replayed later.

FastHook vs simple forwarding

A simple forwarder sends a request somewhere else. FastHook proxy mode also keeps the operational evidence: source auth result, request data, proxy exchange, routed events, ignored branches, transformed payloads, destination attempts, retry state, alerts, and trace history.

Related resources

• Webhook proxy guide
• Request trace page
• Webhook debugger
• Ngrok alternative
• Webhook Relay alternative
• Test webhooks locally

Frequently asked questions