xero-webhooks

Xero Webhooks

When to Use This Skill

• How do I receive Xero webhooks?
• How do I verify the x-xero-signature header?
• Why is my Xero webhook stuck as "inactive" / failing Intent to Receive (ITR)?
• How do I handle CONTACT, INVOICE, CREDITNOTE, or SUBSCRIPTION events?
• How do I fetch the changed record from a Xero webhook payload?

Verification (core)

Xero signs the raw request body with HMAC-SHA256 keyed on the app's webhook signing key, base64-encodes the digest, and sends it in the x-xero-signature header. Capture the raw body before JSON parsing (parsing re-serializes the bytes and breaks the HMAC). Compare timing-safe. The official SDKs (xero-node, xero-python) do not ship a webhook-signature helper — verify manually.

Node:

const crypto = require('crypto');

function verifyXeroSignature(rawBody, signatureHeader, signingKey) {
  if (!signatureHeader) return false;
  const expected = crypto.createHmac('sha256', signingKey).update(rawBody).digest('base64');
  try {
    return crypto.timingSafeEqual(Buffer.from(signatureHeader), Buffer.from(expected));
  } catch {
    return false; // length mismatch = invalid
  }
}

Python:

import hmac, hashlib, base64

def verify_xero_signature(raw_body: bytes, signature_header: str, signing_key: str) -> bool:
    if not signature_header:
        return False
    expected = base64.b64encode(
        hmac.new(signing_key.encode(), raw_body, hashlib.sha256).digest()
    ).decode()
    return hmac.compare_digest(signature_header, expected)

Intent to Receive (ITR): When you save the endpoint, Xero POSTs validation payloads and your server MUST respond within a few seconds: HTTP 200 when the signature matches, HTTP 401 when it does not. Anything else (including a 400) fails ITR and leaves the webhook inactive. Return 401 — not 400 — for a bad signature. The same verify-then-200/401 logic serves both ITR probes and real events.

For complete handlers with route wiring, event dispatch, and tests, see:

• examples/express/
• examples/nextjs/
• examples/fastapi/