LaunchDarkly Webhooks Skill

When to Use This Skill

• How do I receive LaunchDarkly webhooks?
• How do I verify the LaunchDarkly X-LD-Signature header?
• Why is my LaunchDarkly webhook signature verification failing?
• How do I handle feature flag change events (kind: "flag")?
• Why are my LaunchDarkly webhook deliveries unsigned?

Verification (core)

Signing is optional in LaunchDarkly. Only if the webhook has a secret (check Sign this webhook, or set secret via the API) does LaunchDarkly send X-LD-Signature: the HMAC-SHA256 hex digest of the raw request body, keyed with the secret. There is no timestamp and no prefix. Set a secret, or deliveries are unsigned, and your handler should refuse to run without one.

Node:

const crypto = require('crypto');

function verify(rawBody, signatureHeader, secret) {
  if (!signatureHeader || !secret) return false;
  const expected = crypto.createHmac('sha256', secret).update(rawBody).digest('hex');
  try {
    return crypto.timingSafeEqual(Buffer.from(signatureHeader), Buffer.from(expected));
  } catch {
    return false; // different lengths
  }
}

Python:

import hmac, hashlib

def verify(raw_body: bytes, signature_header: str, secret: str) -> bool:
    if not signature_header or not secret:
        return False
    expected = hmac.new(secret.encode(), raw_body, hashlib.sha256).hexdigest()
    return hmac.compare_digest(signature_header, expected)

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

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

Event Types

LaunchDarkly has no event-type header. The payload is an audit log entry, so dispatch on the body's kind field (and accesses[].action for the specific change).

Other fields: _id, date (ms epoch), accesses (action + resource, e.g. updateName on proj/alexis:env/test, or createApprovalRequest), name, description, title, titleVerb, member, target. Which events are sent is controlled by the webhook's policy (actions/resources statements).

For full details, see LaunchDarkly webhooks and the Webhooks API.

Important Headers

Environment Variables

LAUNCHDARKLY_WEBHOOK_SECRET=your_webhook_secret   # The webhook's secret (auto-generated or your own)

Local Development

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

Reference Materials

• references/overview.md - LaunchDarkly webhook concepts and payload
• references/setup.md - Configuration guide
• references/verification.md - Signature verification details