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Auto Fulfill a Specific Shopify Product Using Shopify Flow (No Paid App)

Many Shopify merchants sell a mix of physical and digital products, samples, warranty products, freebies, or items that don’t require manual fulfillment.

Instead of manually fulfilling those products every time an order is placed, you can automate the process using Shopify Flow and the Shopify Admin API.

In this tutorial, I’ll show you how to automatically fulfill a specific item whenever an order is created—without installing any paid app.

What This Automation Does

When a new order is created:

Shopify Flow checks all fulfillment orders.
It searches for a specific SKU.
If the SKU exists in the order:
- The fulfillment order ID is captured.
- The line item ID is captured.
- The quantity is captured.
Shopify automatically creates a fulfillment for that item.

This is useful for:

Digital products
Warranty products
Free samples
Subscription welcome kits
Products fulfilled by external systems
Any item that doesn’t require manual processing

Requirements

Before starting, make sure:

Shopify Flow is installed.
Your store is on a plan that supports Shopify Flow.
The target product has a unique SKU.

For this tutorial we’ll use:

const TARGET_SKU = "FULL";

Replace FULL with the SKU you want to automatically fulfill.

Step 1: Create a New Shopify Flow Workflow

Create a new workflow and select:

Trigger

Order Created

This workflow will run every time a new order is placed.

Step 2: Add a Run Code Action

Add a Run Code step.

Input Query

query{
  order {
    fulfillmentOrders {
      id
      status
      lineItems {
        id
        totalQuantity
        sku
      }
    }
  }
}

This query fetches:

Fulfillment Orders
Line Item IDs
Quantities
SKUs

from the newly created order.

Step 3: Add the JavaScript Logic

Paste the following code inside the Run Code action:

export default function main(input) {
  const TARGET_SKU = "FULL";

  let fulfillmentOrderId = "";
  let lineItemId = "";
  let quantity = 0;
  let shouldFulfill = false;

  const fulfillmentOrders = input.order?.fulfillmentOrders || [];

  for (const fo of fulfillmentOrders) {
    const lineItems = fo.lineItems || [];

    for (const item of lineItems) {
      if (item.sku === TARGET_SKU) {
        fulfillmentOrderId = fo.id;
        lineItemId = item.id;
        quantity = item.totalQuantity;
        shouldFulfill = true;
        break;
      }
    }

    if (shouldFulfill) break;
  }

  return {
    shouldFulfill,
    fulfillmentOrderId,
    lineItemId,
    quantity
  };
}

What This Code Does

The script loops through all fulfillment orders and their line items.

When it finds a line item with the target SKU:

Stores the fulfillment order ID
Stores the line item ID
Stores the quantity
Returns the information for the next workflow steps

Step 4: Add a Condition

Add a condition after the Run Code step:

runCode.shouldFulfill == true

This ensures the workflow only continues when the target SKU is found.

Step 5: Create the Fulfillment via Admin API

Inside the True branch, add a Send Admin API Request action.

Use the following mutation:

{
  "fulfillment": {
    "notifyCustomer": false,
    "lineItemsByFulfillmentOrder": [
      {
        "fulfillmentOrderId": "{{runCode.fulfillmentOrderId}}",
        "fulfillmentOrderLineItems": [
          {
            "id": "{{runCode.lineItemId}}",
            "quantity": {{runCode.quantity}}
          }
        ]
      }
    ]
  },
  "message": "auto fulfilled"
}

This creates the fulfillment for only the matching product.

Step 6: Mark the Fulfillment as Fulfilled

After the Admin API request, add:

Mark Fulfillment Order as Fulfilled

Use:

{{sendAdminApiRequest.fulfillment.id}}

as the fulfillment order ID.

Disable customer notifications if desired.

Workflow Structure

Order Created
    ↓
Run Code
    ↓
Condition (SKU Found?)
    ↓
Yes
    ↓
Send Admin API Request
    ↓
Mark Fulfillment Order as Fulfilled

Flow file: Download AutoFulFill.flow

Customizations

Fulfill Multiple Products

Instead of checking a single SKU:

const TARGET_SKUS = ["FULL", "DIGITAL", "SAMPLE"];

Use:

if (TARGET_SKUS.includes(item.sku))

Fulfill Based on Product Type

You can query additional product data and automate based on:

Product Type
Vendor
Tags
Metafields

Notify Customers

To send fulfillment emails:

"notifyCustomer": true

Benefits of This Approach

✅ No paid apps

✅ Fully automated

✅ Uses native Shopify Flow

✅ Works with Shopify Admin API

✅ Easy to customize

✅ Reduces manual fulfillment work

Final Thoughts

Shopify Flow is one of the most underrated tools available to Shopify merchants and developers.

With a few lines of JavaScript and a simple Admin API call, you can automatically fulfill specific products whenever an order is placed, saving time and eliminating repetitive manual work.

If you’re already using Shopify Flow, this automation can be implemented in just a few minutes and can easily be extended to support more complex fulfillment logic.

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