FlowRelay FlowRelay
View FlowRelay for Shopify Flow

Zapier setup guide

Connect Zapier to Shopify Flow through FlowRelay.

Use a Webhooks by Zapier POST action to send one authenticated JSON event to a FlowRelay endpoint. FlowRelay checks the request, maps the event, and hands the External event trigger to Shopify Flow. The receipt records whether that handoff happened.

Set up your first endpoint Review authentication

Make the first test harmless.

Prove the transport and handoff before any live schedule, production trigger, or business-changing Shopify Flow action depends on it.

FlowRelay

Install FlowRelay, create one test endpoint, and keep its URL and generated authentication value private.

Shopify Flow

Create a workflow with FlowRelay’s External event trigger and a Log output action. Log only the synthetic event type or summary.

Zapier

A paid Zapier plan with Webhooks by Zapier, plus a Zap you can edit without publishing the first synthetic test as live automation.

Configure FlowRelay and Shopify Flow once.

Use the same endpoint mapping for the first synthetic send. Later, replace the sample values with fields from the real Zapier workflow.

Endpoint name
Zapier test to Shopify Flow
Source label
Zapier
Trigger variant
Generic
Default event type
zapier.synthetic.test
Mapped paths
event.type, event.id, event.occurred_at, event.summary
Required paths
event.id and event.type
Authentication
Static header for this guide; prefer HMAC when the sender can sign exact request bytes

In Shopify Flow

  1. Create a workflow and choose FlowRelay from the installed app triggers.
  2. Select External event, which matches the Generic endpoint variant.
  3. Add a Log output action with a synthetic field such as Event type or Summary.
  4. Save and enable the workflow before sending the test event.

Review the FlowRelay trigger setup

Configure Zapier to send the request.

The POST action accepts custom headers. Limit who can edit the Zap because the generated FlowRelay static secret is configured in that step, and rotate it if it is exposed.

  1. 01

    Add Webhooks by Zapier

    Add an action after a controlled test trigger and choose the POST event. Webhooks by Zapier is not available on the Free plan.

  2. 02

    Set the destination and payload type

    Paste the private FlowRelay endpoint URL and choose JSON as the Payload Type.

  3. 03

    Build the nested event object

    In Data, use event__type, event__id, event__occurred_at, and event__summary. Turn Unflatten on so Zapier sends them inside one event object.

  4. 04

    Add the authentication header

    In Headers, enter the exact FlowRelay header name and static secret generated for this endpoint. Do not put either value in a public note or sample.

  5. 05

    Test the action before publishing

    Send the synthetic event from the Test tab, then verify the Zap test, FlowRelay receipt, and Shopify Flow run as three separate facts.

Use synthetic JSON for the first send.

The values below contain no customer, order, token, endpoint, or merchant data. Replace the timestamp with the current test time if that helps you find the run.

Synthetic request body 
{
  "event": {
    "type": "zapier.synthetic.test",
    "id": "zapier-test-001",
    "occurred_at": "2026-07-29T15:00:00Z",
    "summary": "Synthetic Zapier to Shopify Flow test"
  }
}
Zapier request configuration
FieldValue
App and eventWebhooks by Zapier → POST
PlanProfessional, Team, or Enterprise
URLThe private endpoint URL copied from FlowRelay
Payload TypeJSON
Nested fieldsevent__type, event__id, event__occurred_at, event__summary; Unflatten on
HeadersExact generated FlowRelay static-header name and value

Verify three different facts.

A successful sender request, a FlowRelay handoff, and a completed Shopify Flow workflow are not the same fact.

  1. 1Zapier

    The test execution reached the HTTP step and received a 2xx response.

  2. 2FlowRelay receipt

    Authentication, required fields, mapping, Flow readiness, and handoff show the expected state.

  3. 3Shopify Flow

    A separate Recent runs entry shows that the External event trigger started the workflow.

  4. 4Only then

    Replace synthetic values, review side effects, and enable the live schedule or trigger.

Start with the first fact that failed.

Do not change all three systems at once. The earliest missing record identifies where to look next.

The action is unavailable
Confirm the Zapier account has a plan that includes Webhooks by Zapier.
The test returns 401 or 403
Check the exact Headers name and value against the endpoint’s current static-header credential.
The test returns 400
Check Payload Type JSON, turn Unflatten on, and confirm Zapier generated a valid JSON request body.
Zapier receives 202 but there is no Flow run
Open the FlowRelay receipt. A missing event.id or event.type appears there as a mapping failure. Fix a Failed or No workflow receipt first; after Delivered, continue in Shopify Flow.

Sources checked for this guide.

Platform field names and availability were checked against official documentation on July 29, 2026. FlowRelay behavior was checked against the shipped product and current public docs.

Prove one Zapier event before enabling live traffic.

Use a private credential, a synthetic payload, a harmless Flow action, and the receipt-backed handoff check together.

Set up your first endpoint Install FlowRelay