LinkedIn Webhooks Skill

When to Use This Skill

• How do I receive LinkedIn webhooks?
• How do I pass the LinkedIn challengeCode endpoint validation?
• How do I verify the LinkedIn X-LI-Signature header?
• Why is my LinkedIn webhook signature verification failing?
• How do I handle LinkedIn LEAD_ACTION or ORGANIZATION_SOCIAL_ACTION_NOTIFICATIONS events?

LinkedIn webhooks are two endpoints on one URL:

1. GET — endpoint validation. LinkedIn sends ?challengeCode=<uuid> and you echo back a JSON challengeResponse. Re-run every 2 hours; 3 consecutive failures block the endpoint.
2. POST — event delivery. Each request carries an X-LI-Signature header you must verify.

Both use HMAC-SHA256 keyed with your app's clientSecret, hex-encoded. LinkedIn does not follow the Standard Webhooks spec, and there is no linkedin-api-client SDK method for webhook verification — verify manually.

Verification (core)

Two HMACs, both keyed with clientSecret, both lowercase hex. The message differs:

• Challenge (GET): message = challengeCode (the raw UUID).
• Signature (POST): message = the literal string "hmacsha256=" prepended to the raw JSON body. The hmacsha256= prefix lives only in the string-to-sign; the X-LI-Signature header value is the bare hex digest.

Node:

const crypto = require('crypto');

// GET endpoint validation — respond 200 with {challengeCode, challengeResponse} within 3s
function challengeResponse(challengeCode, clientSecret) {
  return crypto.createHmac('sha256', clientSecret).update(challengeCode).digest('hex');
}

// POST signature verification — pass the RAW body, compare timing-safe
function verify(rawBody, signatureHeader, clientSecret) {
  const stringToSign = 'hmacsha256=' + rawBody; // prefix is only in the string-to-sign
  const expected = crypto.createHmac('sha256', clientSecret).update(stringToSign).digest('hex');
  try {
    return crypto.timingSafeEqual(Buffer.from(signatureHeader || '', 'hex'), Buffer.from(expected, 'hex'));
  } catch {
    return false;
  }
}

Python:

import hmac, hashlib

def challenge_response(challenge_code: str, client_secret: str) -> str:
    return hmac.new(client_secret.encode(), challenge_code.encode(), hashlib.sha256).hexdigest()

def verify(raw_body: bytes, signature_header: str, client_secret: str) -> bool:
    string_to_sign = b"hmacsha256=" + raw_body  # prefix is only in the string-to-sign
    expected = hmac.new(client_secret.encode(), string_to_sign, hashlib.sha256).hexdigest()
    return hmac.compare_digest(signature_header or "", expected)

For complete handlers (GET challenge + POST verify + event dispatch + dedupe) with tests, see:

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

Common Event Types

LinkedIn sends no event-type header — identify the notification from the payload body. Webhooks are gated per product behind partner programs.

Talent (Apply Connect) also delivers job status updates and resync requests. See references/overview.md for payloads.

Important Headers

Environment Variables

LINKEDIN_CLIENT_SECRET=your_app_client_secret   # Developer Portal → App → Auth tab

Local Development

LinkedIn requires HTTPS and does not support ngrok. Use the Hookdeck CLI for a supported HTTPS tunnel:

npx hookdeck-cli listen 3000 linkedin --path /webhooks/linkedin

Gotchas

• Use the raw body — never re-serialize or pretty-print the JSON before hashing, or the signature won't match.
• hmacsha256= prefix is part of the string-to-sign only, not the header value.
• Respond to the GET within 3 seconds with Content-Type: application/json, or validation fails.
• Dedupe on notificationId — duplicate deliveries are expected; org social-action notifications retry every 5 minutes for up to 8 hours.
• From 2026-03-16, unvalidated Lead Sync webhooks stop receiving notifications.

Reference Materials

• references/overview.md - LinkedIn webhook concepts, products, event payloads
• references/setup.md - Developer Portal configuration, scopes, subscriptions
• references/verification.md - Challenge + signature verification details and debugging