Why Shopify Webhook HMAC Verification Keeps Failing

You set up the webhook. Got the secret. Wrote the HMAC check. Still getting: HMAC VALIDATION FAILED Or worse — it passes locally but fails Shopify's automated review. Here's every real reason it happens. if you just want all of this handled without thinking about it — Tern fixes every issue below out of the box. keep reading to understand why. 1. You're using the wrong secret This is the most common one and it's not obvious from the docs. Shopify doesn't give you a dedicated webhook secret like Stripe does. You use your app's client secret — the API secret key from your Partner Dashboard. Not the API key. Not the access token. The client secret. # ❌ wrong — this is the API key SHOPIFY_API_KEY = abc123... # ✅ correct — this is what signs webhooks SHOPIFY_API_SECRET = shpss_xyz789... If you're passing the wrong value here every HMAC will fail silently. 2. The signature is base64 — not hex Shopify's X-Shopify-Hmac-SHA256 header is base64 encoded , not hex like Stripe. Most HMAC examples o