Expert Shopify Developer Needed

# Shopify Developer Needed – Integrate Custom Quote Calculator with Shopify Cart & Checkout We are an established Australian custom sticker and label printing business using Shopify. We have already built a browser-based custom quote calculator that allows customers to configure a custom printing order based on variables including: * Product type * Material * Width and height * Quantity * Number of designs * Finishing options * Custom pricing calculations * File uploads We are looking for an experienced Shopify developer to integrate this calculator properly with our Shopify store. ## Project Scope The calculator interface and pricing logic already exist. We need a developer to build the Shopify integration so that when a customer completes the calculator and clicks **Add to Cart**: 1. The correct calculated price is securely passed to Shopify. 2. A Shopify cart line item is created representing the custom product configuration. 3. All relevant order information is attached to the cart line item and remains available throughout: Cart → Checkout → Shopify Order → Order Admin → Fulfilment/Production Workflow. This information may include: * Product type * Material * Finish (e.g. Gloss or Matte) * Width * Height * Quantity * Number of designs * Price * Unique quote/configuration ID * Other production specifications 4. Customer-uploaded artwork files are correctly associated with the order. The production team must be able to reliably identify which uploaded files belong to each order and, where applicable, each design or line item. 5. The calculated price cannot be manipulated by customers through browser developer tools, JavaScript changes, modified requests, or cart quantity changes. The final price must be validated or generated securely before the item is added to Shopify checkout. 6. The solution must support multiple custom products in the same cart without files, specifications, or pricing becoming mixed between line items. 7. The integration must work reliably with Shopify checkout, order creation, payment capture, refunds, customer accounts and our downstream production workflow. ## Important Technical Requirement We are **not looking for a developer to rebuild the calculator from scratch**. We need someone who can review the existing calculator code and recommend and implement the correct architecture for connecting it to Shopify. We are open to using: * Shopify Cart API * Shopify Storefront API * Shopify Functions * Draft Orders * App Proxies * A lightweight custom Shopify app/backend * Metaobjects or metafields * Secure external file storage However, the developer must recommend the simplest reliable architecture that can scale with the business. We do not want unnecessary custom infrastructure or an over-engineered solution. ## Required Experience Please apply only if you have strong experience with: * Shopify custom development * Custom products and dynamic pricing * Shopify cart and checkout architecture * Shopify line item properties * Shopify Functions and/or custom Shopify apps * Secure server-side price validation * File upload workflows * Shopify Admin API * Webhooks * Integrating external applications with Shopify Experience building custom product configurators, calculators, print-on-demand systems, personalised product builders or similar Shopify applications is highly desirable. ## Deliverables The successful developer will: * Review the existing calculator code and pricing logic. * Recommend the appropriate Shopify integration architecture before development begins. * Implement the Add to Cart functionality. * Securely validate calculated pricing. * Ensure all custom product specifications are passed to Shopify. * Implement reliable artwork file handling and order association. * Ensure multiple custom products can exist in the same cart without data conflicts. * Ensure order information is clearly accessible in Shopify Admin. * Provide documentation explaining the architecture and integration. * Provide deployment instructions. * Provide a short warranty period for bug fixes after launch. ## When Applying Please answer the following questions: 1. Have you previously integrated a custom product calculator or configurator with Shopify? Please provide examples. 2. How would you securely handle dynamic pricing so customers cannot manipulate the price before checkout? 3. How would you associate multiple uploaded artwork files with individual Shopify cart line items and orders? 4. Would you recommend using a custom Shopify app/backend, Draft Orders, Shopify Functions, or another architecture for this project? Briefly explain why. 5. How would you prevent customers from changing cart quantities or other cart data in a way that results in incorrect pricing? 6. How would you ensure the solution can later integrate with an artwork proofing and production workflow? 7. Please provide your estimated timeline, fixed-price estimate or hourly rate, and availability. **Important:** Generic applications that do not answer the technical questions above will not be considered.