Twitch Webhooks Skill

Twitch delivers events through EventSub over the webhook transport. Twitch does not follow the Standard Webhooks spec — it has its own signature scheme and a three-way message-type protocol you must handle.

When to Use This Skill

• How do I receive Twitch EventSub webhooks?
• How do I verify Twitch webhook signatures?
• How do I respond to the webhook_callback_verification challenge?
• How do I handle stream.online, channel.follow, or channel.subscribe events?
• Why is my Twitch webhook signature verification failing?

Verification (core)

Twitch signs an HMAC-SHA256 over the concatenation of the Twitch-Eventsub-Message-Id header, the Twitch-Eventsub-Message-Timestamp header, and the raw request body (in that order). The digest is sent in Twitch-Eventsub-Message-Signature as sha256=<hex>. There is no SDK for the webhook transport, so verify manually. Use the raw body and compare timing-safe.

Node:

const crypto = require('crypto');

function verifyTwitchSignature(messageId, timestamp, rawBody, signatureHeader, secret) {
  if (!messageId || !timestamp || !signatureHeader) return false;
  const hmac = crypto.createHmac('sha256', secret);
  hmac.update(messageId);
  hmac.update(timestamp);
  hmac.update(rawBody); // string or Buffer of the raw body
  const expected = 'sha256=' + hmac.digest('hex');
  try {
    return crypto.timingSafeEqual(Buffer.from(signatureHeader), Buffer.from(expected));
  } catch {
    return false;
  }
}

Python:

import hmac, hashlib

def verify_twitch_signature(message_id, timestamp, raw_body, signature_header, secret):
    if not (message_id and timestamp and signature_header):
        return False
    message = message_id.encode() + timestamp.encode() + raw_body  # raw_body is bytes
    expected = "sha256=" + hmac.new(secret.encode(), message, hashlib.sha256).hexdigest()
    return hmac.compare_digest(expected, signature_header)

Message Types

Read Twitch-Eventsub-Message-Type and branch. Verify the signature first for all three types.

Revocation reasons: user_removed, authorization_revoked, notification_failures_exceeded, version_removed.

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

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

Common Event Types

For the full event reference, see Twitch EventSub Subscription Types.

Important Headers

Environment Variables

# The secret you set (10-100 ASCII chars) when creating the subscription via
# POST /helix/eventsub/subscriptions. It is NOT shown in a dashboard.
TWITCH_WEBHOOK_SECRET=your_eventsub_secret_here

Gotchas

• Verify the raw body, not re-serialized JSON — re-serializing changes bytes and breaks the HMAC.
• The subscription secret is set per subscription when you create it via the API with an app access token. User tokens are rejected for the webhook transport.
• The callback must be HTTPS on port 443.
• Respond within a few seconds or Twitch revokes the subscription after repeated failures.
• Delivery is at-least-once — dedupe on Twitch-Eventsub-Message-Id and reject timestamps older than 10 minutes.
• channel.follow requires version 2 with a moderator_user_id condition; channel.update is version 2.

Local Development

# Start tunnel (no account needed)
npx hookdeck-cli listen 3000 twitch --path /webhooks/twitch

Reference Materials

• references/overview.md - Twitch EventSub webhook concepts and events
• references/setup.md - Creating subscriptions and the signing secret
• references/verification.md - Signature verification details and gotchas