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Ecommerce & Retail · Shopify Apps

Shopify Stock Reservation System

We launched a public Shopify application that provides merchants with timed cart reservations to reduce abandoned carts and improve inventory accuracy.

Shopify Stock Reservation System
Focus
SHOPIFY, MICRO-SAAS, CUSTOM-WEB-APP, SAAS
Delivered
16 Dec 2025
Location
Germany

Outcome

Thousands of themes get a countdown timer; stock held via Draft Orders until it expires.

The Vision & Challenge

Our partner, an e-commerce software developer, identified a specific point of failure in high-volume online stores. Their goal was to build and launch a Micro-SaaS application on the Shopify App Store, creating a new, recurring revenue stream.

The central problem was inventory paralysis caused by abandoned carts. When a customer adds a high-demand, low-stock item to their cart but does not check out, that item is functionally removed from sale. This results in lost sales from other interested buyers and creates inaccurate stock levels, a critical issue for any merchant.

Robust Devs was engaged to design and build the complete application from the ground up. We developed a system that integrates directly with Shopify to place a temporary, timed hold on items in a customer's cart. This creates fair urgency for the buyer and automatically returns the inventory to the public pool if the sale is not completed.

The challenge

  • Maintaining perfect, real-time data synchronization between the storefront cart, our application's backend, and Shopify's inventory system was essential.
  • The frontend timer component had to be injected and function correctly across thousands of unique Shopify themes without manual configuration by the merchant.
  • The system required a flexible rules engine, allowing merchants to set different reservation durations for different tiers of customers.

How we solved it

  • We built a Laravel backend that utilizes Shopify’s Draft Order API and webhooks. This creates a reliable, two-way sync that reserves inventory and reflects any cart changes, whether made by the customer or the admin.
  • A theme-agnostic JavaScript module was written to intelligently scan the store’s DOM and place the countdown timer in the correct location on cart and product pages, ensuring wide compatibility.
  • We developed a merchant-facing admin panel using Shopify Polaris. Inside, merchants can create rules that link reservation times to specific customer tags, enabling custom sales strategies for VIPs or first-time buyers.
Three reservation windows shown as rings of increasing length. When any customer adds a high-demand item to their cart, the app provisionally reserves that unit through Shopify’s Draft Order API, removing it from the public stock count so the merchant’s inventory stays accurate and the item cannot be oversold. How long the hold lasts is set against Shopify’s native customer tags: a new visitor gets the shortest window, a returning customer the standard one, and a tagged VIP the longest. If checkout does not complete, the unit returns to sale automatically.

Technologies

What we built it with

Front-end
  • JavaScript
  • ReactJS
  • HTML5
  • CSS3
Back-end
  • PHP
  • Laravel
DevOps
  • Linux
  • Digital Ocean
  • AWS
Database
  • MySQL
Also used
  • Shopify Polaris
Integrations
  • Shopify
Project screen

Real-Time Inventory Reservation

When a customer adds an item to their cart, our system instantly communicates with the Shopify Draft Order API to provisionally reserve that unit. This action removes it from the public-facing stock count, preventing overselling and giving the merchant an accurate, real-time view of available inventory.

Tiered Reservation Timers

The application allows merchants to define unique reservation windows based on Shopify's native customer tags. A store owner can set a longer timer for a VIP customer and a shorter one for a new visitor. This gives merchants a granular tool to manage demand and reward customer loyalty.

How we built it

Used Shopify's own Draft Order API to hold the stock, and a DOM-scanning script to place the timer in any theme. Holding inventory for a cart needs something Shopify can honour on its side, so the Laravel backend creates a draft order for each reservation and listens to webhooks, giving a two-way sync that reflects changes whether the customer or the admin made them. The timer had to work across thousands of unique themes with no configuration, so the JavaScript module scans the DOM for the right place on cart and product pages and inserts itself there. Merchants tie reservation lengths to customer tags in a Polaris panel, which turns a hold into a VIP or first-buyer strategy.

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