Case Study: Custom Shopify Middleware Solution to Calculate Prices & Taxes of Individual Bundle Items

Leveraging our extensive experience and expertise in custom Shopify app development, we recently built a bespoke middleware solution for a Swiss foodtech startup facing complex tax requirements.

Having raised a Series A in 2021, the client had initially developed a fully bespoke ecommerce solution in-house. In 2022, they asked Swanky to support them with a migration to Shopify Plus. One of the most challenging elements of the project was implementing a middleware solution to enable different rates of VAT to be charged on different products, which was further complicated by subscription bundle dynamics, variable pricing and serving international markets.

This case study explores the challenges our client was facing and the solution we built to overcome these.

Context: Individual price details required for ‘child’ items in a bundle

Before discussing the details of the middleware solution, it’s important to understand the context in which it was developed.

The wider project with this client leveraged Recharge’s native bundling functionality. This involved the creation of ‘parent’ products in Shopify and Recharge (the subscription boxes), which were then configured to be made up of a set number of ‘child’ products from our client’s product catalogue. The customer would then be instructed to pick a certain number of child products to meet a predetermined box value.

This setup meant that when orders were exported, the bundle line item appeared as a single product on the order, with the total price as its line item price. Meanwhile, the child products were added to the order valued at zero.

This posed a problem for our client, as its ERP (Enterprise Resource Planning Software) required that any tax and discount calculations happen at a line item level. Because of the idiosyncrasies of this system, they needed bundle orders to be exported to the ERP with correct individual prices for child items, along with relevant taxes and discounts – rather than a total price for the bundle and zero-priced child items.

How Swanky helped: Custom Shopify app development

Our app development team designed a custom Shopify app which would act as a middleware, exporting orders from Shopify and importing them into the client’s ERP system.

To ensure that individual line items, when uploaded, had correct and accurate financial information, we wrote a series of transformation functions within the middleware which would calculate the line item prices, taxes and discounts (extrapolated from the bundle price) and apply them to the line items in the order before being imported into the ERP.

A further complication was that Germany and Austria have different taxes applied to dairy alternatives – a category many of our client’s products fell into. This meant that the taxes on many items were not constant across the various countries where they trade, something which the middleware had to take into account.

As the export had to run twice a day – once before the warehouse picking and packing staff arrived for the morning shift and again mid-morning – it had to be efficient, performant and able to scale with the business as it expands through Europe.

Ultimately this project enabled the client to pursue a migration to Shopify Plus – reducing cost, complexity and legacy issues associated with the previous bespoke store – whilst broadening its customer offering (via subscriptions) and ensuring both tax compliance and effective back-end business operations.

Do you require custom app or middleware development on Shopify?

If you’re looking for a trusted Shopify Plus agency to consult on and implement complex custom development work for your website, then we’d encourage you to get in touch for a chat with our friendly team of ecommerce experts.

We’ve built bespoke Shopify apps for a range of needs and environments, including:

• Custom credit app for B2B retailer Saddleback
• Bespoke made-to-measure product builder for Australian brand Veneta Blinds
• Custom checkout solution to handle VAT exemption for online retailer Glebe Healthcare

Contact us today to learn more about how we could help unlock your ecommerce potential.