AI Webhook Debugging: Diagnose Failures in One Click

Every webhook developer knows this moment: a delivery shows 400 or 500, the dashboard says "failed," and now you're a detective. Was it the signature? The raw body? The wrong secret? A field you didn't expect? You open three browser tabs, re-read the provider's docs, add console.log lines, and trigger another real event to reproduce it.

That whole workflow is what AI webhook debugging replaces. Anonymily reads the failed exchange the way an expert would — the payload, your handler's actual response, and the signature-verification result — and tells you exactly why it failed and what to change. It's the one thing no generic tunnel or webhook inspector does, because it requires understanding webhooks, not just relaying bytes.

The pain: failures that don't explain themselves

A failed webhook gives you almost nothing to go on. The provider's dashboard shows a status code and maybe a truncated response body. The signal is all on your side — and it's scattered:

Was the signature valid? (If not: raw-body bug? wrong secret? wrong encoding?)
What did your handler actually return, and why?
Does the payload shape match what your code assumed?
Is this a test/live mode mismatch?

Correlating those by hand, under time pressure, is the slow part of webhook work. The fix is usually one line — finding it is the cost.

The painful manual way

Find the failed delivery in the provider dashboard.
Copy the payload out (if it's even shown in full).
Re-read the signature docs to check your verification logic.
Add logging, redeploy or restart, and trigger another real event to reproduce.
Stare at the diff between "what I expected" and "what arrived."
Repeat until it clicks.

It works, but it's archaeology, and step 4 means polluting real systems just to reproduce a bug.

The Anonymily way: one-click diagnosis

Anonymily captures the full exchange — request bytes, headers, signature result, and what your localhost returned — so the diagnosis has real signals to reason over. Then it produces a specific, actionable explanation, not generic advice.

In your editor (the one-click path)

Anonymily ships an MCP server, so you can ask in plain English right inside Claude or Cursor — no context-switching to a dashboard:

"Diagnose the last failed request on hook ab12cd34."

Under the hood that calls the diagnose_request tool and returns a structured diagnosis:

{
  "diagnosis": "Your endpoint returned 400 because the Stripe signature didn't match. The body was re-serialized after JSON parsing, changing the byte sequence the HMAC was computed over.",
  "recommendations": [
    "Use express.raw({ type: 'application/json' }) on the webhook route so req.body stays the raw Buffer.",
    "Pass that raw Buffer to stripe.webhooks.constructEvent, not a re-stringified object.",
    "Confirm STRIPE_WEBHOOK_SECRET matches this specific endpoint."
  ],
  "severity": "error"
}

That's the exact root cause and the fix — derived from your captured request, not a generic checklist.

From the API / CLI

The same diagnosis is one authenticated call:

curl -X POST \
  https://api.anonymily.com/v1/hooks/<hookId>/requests/<requestId>/diagnose \
  -H "Authorization: Bearer $ANONYMILY_TOKEN"

You capture the request once with npx @anonymilyhq/cli listen 3000, then diagnose any request in its history.

How the diagnosis actually works

It's grounded in structured signals, which is why it's specific rather than hand-wavy:

Provider detection — identifies the provider from headers/shape so advice is provider-correct.
Signature result — whether the HMAC verified, and if not, the likely reason (raw-body, secret, encoding, stale timestamp).
Your handler's response — the actual status code and body your localhost returned (Anonymily captures the response, not just the request).
Payload analysis — the real event type and fields versus what a handler for that event expects.

If the AI is ever unavailable, Anonymily falls back to a deterministic diagnosis built from those same signals — so a failed delivery always gets some actionable explanation, never a spinner.

Why this is genuinely unique

A tunnel (ngrok) forwards bytes — it can't tell you why a webhook failed. A webhook inspector shows you the request — but you still do the reasoning. Anonymily is the only tool that captures the full exchange including your handler's response and then explains the failure. That's the difference between "here's the data, good luck" and "here's the bug and the fix."

See the honest comparison in Anonymily vs ngrok.

Try it

Capture your webhooks:
```
npx @anonymilyhq/cli listen 3000
```
Let a failing event hit your handler (real, synthetic, or replayed).
Ask Anonymily to diagnose it — in your editor via MCP, or via the API.

You'll get the cause and the fix in seconds, not a debugging session.

Next steps

Auto-generate a webhook handler from a real payload — go from diagnosis straight to corrected code.
How to verify webhook signatures (HMAC) — the bug class diagnosis catches most often.
The Complete Guide to Webhooks — the full mental model.

TL;DR

Failed webhooks don't explain themselves, and reconstructing the cause by hand is the slow part of webhook work. Anonymily captures the full exchange — payload, signature result, and your handler's response — and an AI turns it into a specific root cause plus the fix, one click from your editor or one API call:

npx @anonymilyhq/cli listen 3000