Shopify Custom App Developer Needed – API + Webhooks + Order Metafields Automation

@Microlent

Hello! This is a clean automation layer, not a storefront change, which is exactly how it should be built. The key here isn’t just connecting APIs. It’s ensuring idempotent webhook handling, clean metafield schema design, and reliable event-driven updates between Shopify and LegitApp. I would structure this as: • Shopify custom app (Node-based backend) • Secure orders/paid webhook listener • Idempotent intent creation with external Bearer-auth API • Structured metafields namespace for intent ID, submission URL, status, certificate link • External webhook receiver with signature validation • Status-driven email notifications via SendGrid or Klaviyo • Order page app block to surface authentication status inside Shopify The important part is handling webhook retries safely and preventing duplicate intent creation. Yes, I’ve built Shopify custom apps integrating third-party REST APIs with bidirectional webhook workflows, including payment-state-driven automations and external verification services. One clarification before scoping timeline: Do you prefer this as a private custom app for your store only, or a public app structure for future scalability? Happy to outline the full event flow before we begin. Best, Jenifer

@extreamcode

Hi, Understanding the intricacies behind your Shopify authentication workflow, I see how crucial it is to flawlessly glue your store to LegitApp’s backend for a smooth, automated customer journey. With extensive Shopify custom app development experience, especially integrating REST APIs and handling webhooks, I’m confident in delivering the precise backend service you need , syncing order metafields, handling webhook events, and automating emails using tools like SendGrid or Klaviyo. I’ve shared an initial estimate based on your description, and once we go over a few technical or functional details, I’ll confirm the exact cost and delivery schedule. The next step will be crafting a robust, secure app that seamlessly communicates between Shopify and your external service, accompanied by clear documentation and setup guidance. Could you share any existing documentation or API details for the LegitApp authentication service to better understand the integration scope? Thanks, Asad

@Shaiwan

Hello!!! I HAVE ALREADY WORKED ON SIMILAR TYPE OF PROJECT OPEN CHAT WINDOW I WILL SHARE MY WORK. Will this be a private custom app for a single store or public app architecture? Do you already have webhook event schemas and API documentation from LegitApp available for testing? What I offer: ⭐ Custom Shopify app with secure backend architecture ⭐ orders/paid webhook integration with validation ⭐ External REST API integration with Bearer authentication ⭐ Webhook listener with event-based order metafield updates ⭐ Automated email notifications via SendGrid or Klaviyo ⭐ Order status UI block with authentication progress + certificate link With 7+ years of experience in Shopify custom apps, API automation, and webhook-driven systems, I ensure stable and scalable integrations. First, I will design the webhook and API flow mapping. Then build and test metafield automation in staging. Finally deploy with documentation and setup guidance. Let’s discuss your workflow in detail. Best Regards, Shaiwan Sheikh

@monicasynthesis

Hello, I’ve gone through your job description and understand that you’re looking for an experienced Shopify developer to build a small custom backend app to integrate your store with the LegitApp external authentication service. With 5+ years of experience in Shopify custom apps, webhooks, and API integrations, I’ve successfully delivered similar backend automation projects. What I can help you with: • Develop a Shopify custom app or secure backend to handle orders, external API calls, and webhook events • Store authentication intent, submission URL, and status in Shopify order metafields • Send customer email notifications via SendGrid/Klaviyo based on webhook updates • Display authentication status and relevant buttons inside Shopify order history Warm regards, Monica Bhatia

@billybryan98

Hello, I’ve built reliable Shopify backends that talk to external APIs and handle webhooks end-to-end, without touching themes or storefront UI. My approach is to design a small, secure backend app that sits between Shopify orders and LegitApp, focused on automation, observability, and clean data flow. I’ve previously implemented REST API integrations with Bearer authentication, Shopify metafields storage for order-level state, and webhook-driven state machines that trigger email notifications and status updates. I’ll replicate that pattern here: on order paid, create an authentication intent via LegitApp, store intent ID and urls in order metafields, and email the customer with the submission link. As LegitApp webhooks arrive, I’ll update metafields and notify the customer, so the authentication status is visible in the Shopify order history. I can handle the full stack using a compact, well-documented backend, with clear setup steps and a clean, tested codebase. Please feel free to reach out so we can discuss specifics and timeline. I’m looking forward to collaborating. Best regards, Billy Bryan

@arshig8

Hello, As an experienced Shopify developer, I am highly skilled in building custom apps and integrating APIs and webhooks. I have a deep understanding of Shopify's metafields system, including the ability to store and update data effectively. This intricacy aligns perfectly with your specific project requirements. Not only have I developed projects that utilize webhooks and external APIs extensively, but I have also integrated backend services and utilized REST APIs for secure authentication processes. What sets me apart is my holistic approach to digital solutions. Beyond the backend development, I am well-versed in creating engaging UI for a smooth user experience—a skill that will come in handy when crafting the order page UI block showing status and buttons as requested in your project description. Additionally, my expertise in Email API integration ensures seamless communication between your customers and the authentication service throughout the entire process. Lastly, my commitment to delivering clear documentations along with clean codes will ensure that you have a fully automated workflow that is easy to maintain and comprehend. Combined with my dedication to providing tailored solutions that help businesses stand out in the online market, hiring me guarantees a solution-oriented and a highly professional execution of your project. Thanks, Arshiya

@jayprakashyadav

With over 15 years of experience in the web development field, I have gained considerable mastery in Shopify app development and API integration – which makes me an excellent fit for your project. If you choose to work with me, you're guaranteed a solution for your custom backend app that will seamlessly integrate your Shopify store with LegitApp, through effective utilization of webhooks, order metafields and REST API. Throughout my career, I have built numerous Shopify custom apps like the one you require. For instance, I recently developed an app utilizing OPEN AI API for auto-generating articles and images along with social share. This is proof enough that I can handle the automation aspect that your project entails without missing a beat. Moreover, I understand and appreciate the need for clean and well-documented code. Thus, once I complete this project for you, you'll not only have a fully automated workflow but also proper setup instructions that make it easy to manage even after my work is done. It'll be great working with you on this small yet impactful integration project. Let's get started! Thanks, Jay

@Rajoriadares

Hello Client, Greeting of the day!!!! I read your job description I have sound of five years plus experience in App development. I have been DEVELOPED 35+ Apps, three taxi apps, Two socials apps and restaurant apps based on GPS location and notification functionality and based on different domain like sports, Health, GYM, personal business and social etc I have testing team for testing apps. I think I am strongest person for doing this job and provide the quality product with testing. I am always available for your support. Thanks Sr. Mobile Developer

@efanntyo

Hi there, ⭐ I’m Efanntyo, a seasoned full-stack developer and AI specialist with deep expertise in Shopify app development, RESTful integrations, and webhook-driven automation. I’ve built multiple Shopify custom apps that connect to external services via secure APIs, manage order-level data in Shopify metafields, and automate customer communications end-to-end. For your project, I will deliver a focused backend integration (no UI edits) that seamlessly orchestrates: (1) on order paid, a backend call to LegitApp to create an authentication intent, (2) capture and store the intent ID, hosted submission URL, and status in Shopify order metafields, and (3) trigger customer emails with the submission URL. Core approach: - Build a secure Shopify custom app or backend service with easy rotation of credentials and proper scope management for order metafields. - Implement Shopify webhooks for orders/paid and robust external API integration using Bearer authentication, with retry strategies and clear error handling. - Create an external webhook receiver to process events (initial submission, extra photos, completion) and map them to Shopify metafields and customer notifications. - Email automation via a reliable provider (SendGrid/Klaviyo) to keep customers informed at each webhook event. - Expose a lightweight Order UI block to display status, results, and actionable buttons inside the Shopify order page. - Deliver clean, well-documented code with basic setup instructions and test

@valeriaperezw6

Hello, Greetings , Good evening! I’ve carefully checked your requirements and really interested in this job. I’m full stack node.js developer working at large-scale apps as a lead developer with U.S. and European teams. I’m offering best quality and highest performance at lowest price. I can complete your project on time and your will experience great satisfaction with me. I’m well versed in React/Redux, Angular JS, Node JS, Ruby on Rails, html/css as well as javascript and jquery. I have rich experienced in RESTful API, App Developer and Shopify Development. For more information about me, please refer to my portfolios. I’m ready to discuss your project and start immediately. Looking forward to hearing you back and discussing all details.. Thank you for your attention

@QuickMentor

Shopify Custom App Developer Needed – API + Webhooks + Order Metafields Automation I'm excited after reviewing your project details! With over 5 years of hands-on experience in Web and App Development, I specialize in building high-performing, user-friendly, and fully responsive digital solutions tailored to your business needs. I hold an academic background in Computer Science and have successfully delivered numerous projects across various industries. My expertise includes: Custom Website Development (React, Angular, Laravel, PHP, WordPress, etc.) Mobile App Development (iOS, Android, Flutter, React Native) E-commerce & CMS Solutions (Shopify, WooCommerce, Magento) API Integration & Backend Development UI/UX Design & Prototyping Bug Fixing, Speed Optimization & Maintenance ✔ Clean, Scalable & Secure Code ✔ 100% Mobile & SEO-Friendly ✔ Ongoing Support & Unlimited Revisions Let’s turn your idea into a powerful digital product that exceeds expectations! Check my profile: https://www.freelancer.com/u/QuickMentor Looking forward to working with you!

@GameOfWords

Shopify Custom App Developer Needed – API + Webhooks + Order Metafields Automation I’m a full-stack software engineer with expertise in React, Node.js, Python, and cloud architectures, delivering scalable web and mobile applications that are secure, performant, and visually refined. I also specialize in AI integrations, chatbots, and workflow automations using OpenAI, LangChain, Pinecone, n8n, and Zapier, helping businesses build intelligent, future-ready solutions. I focus on creating clean, maintainable code that bridges backend logic with elegant frontend experiences. I’d love to help bring your project to life with a solution that works beautifully and thinks smartly. To review my samples and achievements, please visit:https://www.freelancer.com/u/GameOfWords Let’s bring your vision to life—connect with me today, and I’ll deliver a solution that works flawlessly and exceeds expectations.

@TeamGTW

Hello! I understand you need a Shopify custom backend app to integrate your store with the LegitApp external authentication service. The workflow includes triggering the API after order payment, storing intent data in Shopify order metafields, handling external webhooks for status updates, sending customer email notifications, and displaying authentication status inside the Shopify order history. The project is mainly backend automation with secure API and webhook handling, not frontend UI development. I have 6 years of experience building Shopify custom apps, API integrations, and webhook-based automation systems. My focus will be on creating a secure and reliable integration that automatically manages authentication intents, webhook processing, metafield updates, and customer notifications. I will ensure clean architecture, proper error handling, and scalable code so the system remains stable as order volume grows. I specialize in backend integrations where multiple systems must communicate smoothly and securely. I have previously worked on Shopify apps involving webhooks, external APIs, and automation workflows, and I can share relevant examples in private chat. I ALSO OFFER THREE MONTHS OF SUPPORT AFTER DELIVERY TO ENSURE EVERYTHING RUNS SMOOTHLY, AND I’D BE HAPPY TO SHARE RELEVANT PROJECT EXAMPLES IN A PRIVATE CHAT. Let’s connect to discuss timeline and implementation details. Best regards, Nikita Gupta

@techwagger

As an Application Solution Architect with extensive experience in Shopify custom app development, webhooks, REST API integration and Shopify metafields, I am confident in my ability to successfully execute this project for you. I have the proficiency to develop a fully automated workflow between your Shopify store and the LegitApp authentication service API. This includes effectively processing webhooks events and updating Shopify order metafields in real-time. Furthermore, I am well-versed in integrating email services using platforms like SendGrid and Klaviyo which would ensure smooth communication between you, your customers and the external authentication service throughout the process. Prioritizing clean, documented codes and offering cohesive system setup instructions to clients is a standard practice for me. With a firm belief in using innovative solutions backed by emerging technologies, my goal is to not only deliver a top-notch application but also enhance the overall user experience and optimize your bottom line. Please review our extensive technology expertise above and let me know if there are any specific examples or solutions you would like to explore further. Thank you once again for your time and consideration; I look forward to connecting with you!

@TechWagger2026

As a seasoned and adaptable Shopify developer, I’ve successfully tackled numerous projects dealing with API integrations, webhook management, Shopify metafields, and more. One such project I’d like to highlight is when I built a Shopify custom app for an e-commerce client using webhooks and external APIs. In addition to my extensive experience in web development — be it in PHP (Core, Laravel, etc.) or as a full stack developer using MERN/MEAN — my skills encompass a wide range of areas critical to the success of this project. Not only am I proficient in REST API integration and Email API integration (which means integrating the external authentication service API you need would be second nature to me), but my competency with Frontend technologies such as HTML5, CSS, TailwindCSS would ensure the slight UI block you’re requesting fits seamlessly into your existing system. Ultimately, opting for my services guarantees you the benefit of all these skills rolled up into one reliable package that consistently produces results. You can count on not just an accomplished developer but also a communicative collaborator committed to exceeding your expectations. I’m excited about the possibility of partnering with you on this project and discussing how we can optimize Shopify store operations through our solution!

@Syedh1998

You already have the external authentication flow built, what you need is a reliable backend bridge that keeps Shopify orders, metafields, and customer notifications perfectly in sync. This is about clean automation, not theme tweaks. I’d build this as a secure Shopify custom app that listens to orders paid webhooks, triggers the external API with proper Bearer authentication, captures the intent ID and hosted submission URL, and writes them into structured order metafields. The app would also handle outgoing email notifications through SendGrid or Klaviyo, ensuring customers receive their submission link immediately after payment. For incoming external webhooks, I’d implement a verified webhook receiver with signature validation, idempotent processing, and clear status mapping to Shopify metafields. Each event updates order status, result, and certificate link while triggering the correct customer notification. I can also add an order status block extension so customers see authentication progress directly inside their order history. I’ve built Shopify custom apps integrating third party APIs and webhook driven workflows where reliability and data consistency were critical. If helpful, I can outline the exact webhook architecture and data model before we begin. Syed

@rbtech1984

Hello There!!! ★★★★ ( Shopify Custom App & Webhook Automation ) ★★★★ I understand you need a lightweight Shopify backend app to connect paid orders with LegitApp via API, store results in order metafields, and automate email + webhook updates. Focus is reliable glue automation, not UI work. ⚜ Shopify custom app backend setup ⚜ orders/paid webhook automation ⚜ External REST API (Bearer) integration ⚜ Order metafields status management ⚜ External webhook receiver handling ⚜ Automated customer email triggers ⚜ Order status UI block support I have 9+ years experience building Shopify automations and webhook driven systems. I’ve built similar flows syncing orders with third-party verification and fulfillment APIs. My approach: Node.js or Laravel secure app, verified webhooks, queue-based processing, and clean metafield structure so future scaling is easy and stable. Yes — I have built Shopify custom apps using webhooks and external APIs and can share examples in chat. Let’s discuss and get this running smoothly. Warm Regards, Farhin B.

@PrateekP3003

Hello! As per your project post, you’re looking to build a small Shopify custom backend app that integrates your store with the LegitApp external authentication API using webhooks, metafields, and automated email notifications. Am I right? I'M GLAD TO SAY THAT I HAVE EXPERIENCE BUILDING SHOPIFY CUSTOM APPS WITH WEBHOOK-DRIVEN API INTEGRATIONS. The goal will be to create a fully automated, secure glue layer between Shopify and the external service without touching theme UI or interfering with existing workflows. My focus will be on implementing: • Shopify webhook listener for orders/paid • Secure REST integration with the external API to create authentication intents • Storing intent ID, submission URL, and status inside Shopify order metafields • Webhook receiver for external status updates • Automated email notifications via SendGrid or Klaviyo I will build this as a Shopify custom app (Node.js or Python backend) using secure webhook validation, structured logging, and scalable architecture. I specialize in webhook-based automation systems and external API integrations within Shopify environments. Yes, I have previously built Shopify custom apps that sync order data with third-party services via webhooks and REST APIs, and I can share relevant examples upon request. I am confident I can deliver this integration smoothly and efficiently. Best regards, Prateek

@abdullahbhabh

As a seasoned developer with a laser focus on Shopify, I'm confident I have the skills and experience necessary to create a robust and streamlined integration for your store. Over the past decade, I've built custom apps for similar scenarios, successfully working with complex webhooks and APIs to tie external services to Shopify stores. To give you an example, for one of my previous clients, Shop2Door, I built detailed backend logic to automate their stock management system quite similar to your requirements. Choosing me means choosing reliability. From our initial conversations through the delivery of your fully automated, glitch-free workflow, you can count on clear communication and adherence to deadlines. Let's discuss your project in detail and bring increased efficiency to your Shopify store!