orb-webhooks

Orb Webhooks

When to Use This Skill

• Setting up Orb webhook handlers
• Debugging Orb signature verification failures
• Understanding Orb event types and payloads
• Handling usage-based billing, subscription, or invoice events

Verification (core)

Orb signs every webhook with HMAC-SHA256 over the literal string v1:{X-Orb-Timestamp}:{rawBody}. The hex digest is delivered in X-Orb-Signature prefixed with v1= (e.g. v1=abc123…). The ISO 8601 timestamp arrives separately in X-Orb-Timestamp. Use the raw request body — don't JSON.parse first.

The orb-billing SDK (npm and PyPI) does not expose an unwrap()/constructEvent() helper at this time, so manual HMAC verification is the canonical path in every framework.

Node:

const crypto = require('crypto');

function verifyOrbSignature(rawBody, signatureHeader, timestamp, secret) {
  if (!signatureHeader || !timestamp) return false;
  const provided = signatureHeader.startsWith('v1=') ? signatureHeader.slice(3) : signatureHeader;
  const expected = crypto
    .createHmac('sha256', secret)
    .update(`v1:${timestamp}:${rawBody}`)
    .digest('hex');
  try {
    return crypto.timingSafeEqual(Buffer.from(provided, 'hex'), Buffer.from(expected, 'hex'));
  } catch {
    return false;
  }
}

Python:

import hmac, hashlib

def verify_orb_signature(raw_body: bytes, signature_header: str, timestamp: str, secret: str) -> bool:
    if not signature_header or not timestamp:
        return False
    provided = signature_header[3:] if signature_header.startswith("v1=") else signature_header
    expected = hmac.new(
        secret.encode(), f"v1:{timestamp}:".encode() + raw_body, hashlib.sha256
    ).hexdigest()
    return hmac.compare_digest(provided, expected)

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

• examples/express/ — Full Express implementation
• examples/nextjs/ — Next.js App Router implementation
• examples/fastapi/ — Python FastAPI implementation