Workflow WebhooksWorkflow Webhooks

How to connect Standard Webhooks to Shopify Flow

Standard Webhooks is an open specification for signing webhooks, used by OpenAI, Supabase Auth Hooks and a growing list of services. One preset covers all of them. Workflow Webhooks turns that call into a Shopify Flow trigger, so your store can react to it: tag a customer, add an order note, send an internal email, update a metafield - anything Shopify Flow can do.

This guide sets up the whole path - Standard Webhooks sends, Workflow Webhooks receives and verifies, Shopify Flow acts - with Standard Webhooks's HMAC signature checked on every request, so nothing but Standard Webhooks can start your workflow.

What you can build

  • Take an OpenAI webhook - a finished batch job or a completed response - and have Flow act on the result in your store.
  • React to a Supabase Auth Hook, so a signup in your own app tags the matching Shopify customer.
  • Receive from any service that follows the standardwebhooks.com spec without configuring a custom signature.

Typical events to send: any event the sending service defines.

The same preset also verifies webhooks from OpenAI, Supabase Auth Hooks.

Before you begin

  • Workflow Webhooks installed on your Shopify store.
  • Shopify Flow installed, which is free from the Shopify App Store.
  • An account on Standard Webhooks with permission to create webhooks.

Step 1 - Create the webhook in Workflow Webhooks

  1. Open Workflow Webhooks -> Webhooks -> Create webhook and give it a name you will recognise in Flow, such as Standard Webhooks events.
  2. Under Authentication, choose HMAC.
  3. Under Signature provider, pick Standard Webhooks. The app fills in the header, algorithm, signed payload and replay window for you - there is nothing else to configure.
  4. Leave the secret empty for now and Save. Copy the webhook URL shown on the page.

See Authentication for the other authentication modes, and Payload mapping and Flow variables for choosing which fields reach Flow.

Step 2 - Add the endpoint in Standard Webhooks

Add the URL as the endpoint in the sending service, then copy the signing secret it shows you (it starts with whsec_).

How to find your Standard Webhooks signing secret

The signing secret starting with whsec_. Paste it whole; if it is shown as v1,whsec_... (Supabase), leave out the leading "v1,".

Standard Webhooks's own documentation on webhook signatures has the exact wording and screenshots for your account.

Paste that secret into the webhook's Secret field in Workflow Webhooks and save. From that moment every Standard Webhooks delivery is verified before it reaches Flow.

What this checks

What Value
Signature header webhook-signature
Where the signature sits The header value, after the prefix v1,
What is signed {header:webhook-id}.{timestamp}.{body}
Signature HMAC-SHA256, base64 encoded
Timestamp The webhook-timestamp header, as Unix seconds
Replay protection Requests whose signed timestamp is more than 5 minutes away from now are rejected
The secret Base64-decoded before use. The leading whsec_ is stripped before decoding. Paste it exactly as the sender shows it

In the signed payload, {body} is the raw request body, byte for byte, and {timestamp} is the timestamp above, and {header:webhook-id} is the webhook-id request header.

A request that fails any of these is rejected with 401, is recorded in History and troubleshooting, and never starts a workflow.

Step 3 - Build the Shopify Flow workflow

  1. In Shopify Flow, create a workflow and choose the Workflow Webhooks trigger.
  2. Press Record events, then send a test event from Standard Webhooks (or use Send test in Workflow Webhooks) so Flow learns the shape of your data.
  3. Every webhook you own fires the same Flow trigger, so add a first condition on the webhook id to keep this workflow to Standard Webhooks only. The id is shown on the webhook page.
  4. Add your actions - tag a customer, add a note, send an internal email, update a metafield.

Step 4 - Test it end to end

Trigger a real event in Standard Webhooks. In Workflow Webhooks -> History you should see the invocation with status Success. If the signature was wrong you get a failed entry with the reason instead, and Verifying signed webhooks explains the signature tester that shows you exactly which step failed.

The signature does not match▾

In this order: the secret (the most common cause - an extra space, or a key from the wrong environment), whether the sender is using a different endpoint's secret, and whether anything between Standard Webhooks and the app rewrites the body. Signatures cover the raw bytes, so a proxy that re-formats JSON breaks them. The signature tester on the webhook page shows the exact text that was signed.

I get 401 on every request▾

Check that the webhook's authentication is set to HMAC with the Standard Webhooks provider selected, that the secret is filled in, and that Standard Webhooks is posting to the URL exactly as the app shows it, including the code at the end.

Nothing appears in History▾

The request never arrived. Re-check the URL in Standard Webhooks, and look at Standard Webhooks's own delivery log for the response it got. A 404 means a wrong or deleted webhook, a 429 means you are over your plan's invocation limit - see Plans and usage.

The workflow runs for the wrong events▾

Every webhook in your store fires the same Flow trigger. Add a condition on the webhook id as the first step of the workflow, or narrow the events you send from Standard Webhooks.

Requests fail with "timestamp outside tolerance"▾

Standard Webhooks signs a timestamp and the app rejects anything more than 5 minutes old. This is normally a clock problem on the sending side, or a delivery that Standard Webhooks retried much later with the original timestamp. Retries from the same original request cannot pass; ask Standard Webhooks to send a fresh event.