# Mario Colic **Full Stack Developer** · Shop Circle — Releasit Apps > I build production apps in the Shopify ecosystem at Shop Circle — from storefront to infrastructure. Focused on shipping fast, scalable software that merchants rely on daily. Also available: [all projects](https://mariocolic.com/projects) · [llms.txt](https://mariocolic.com/llms.txt) · [JSON-LD profile](https://mariocolic.com/profile) ## About I'm a full stack developer at Shop Circle on the Releasit Apps team. I build and maintain production Shopify applications end-to-end — from the storefront experience to the backend infrastructure. I care about writing clean, maintainable code and shipping products that solve real problems for real people. ## Experience ### Full Stack Developer — Shop Circle (2025 – Present) _Releasit Apps_ Building and maintaining production Shopify apps serving 150k+ merchants worldwide. Working across the full stack — from React frontends to backend infrastructure — shipping features, resolving complex bugs, and owning entire app lifecycles. **Stack:** React, Next.js, Remix, Nest.js, TypeScript, Shopify, Liquid, GraphQL ### Support Developer — Shop Circle (2024 – 2025) _Releasit Apps_ Specialized in customizing Shopify apps to meet merchant needs using JavaScript and CSS. Leveraged deep knowledge of in-app features and Shopify's data flow to deliver tailored solutions and optimize user experiences. **Stack:** JavaScript, CSS, Shopify, Liquid ## Tech Stack - **Languages:** JavaScript, TypeScript, Lua - **Frontend:** React, Next.js, Remix, Framer Motion - **Backend / Database:** Node.js, Remix, Express, Koa, Prisma, PostgreSQL, DynamoDB, Supabase, Redis - **API:** REST, GraphQL - **Styling:** Tailwind CSS, CSS - **Shopify:** Shopify, Polaris, App Bridge, Shopify CLI, Hydrogen, Theme Kit, Liquid, Shopify Functions, Checkout UI Extensions - **Cloud / Infra:** Vercel, AWS, Cloudflare, Railway, Docker - **Monitoring:** Sentry, CloudWatch, PostHog - **Testing:** Jest, Vitest, Playwright - **Tooling:** Git, GitHub - **Other:** Discord.js, Ace3 ## Projects ### Professional Work #### Releasit COD Form & Upsells — _Built for Shopify_ 1-Click Cash on Delivery order form with pre/post-purchase upsells, downsells, and quantity offers to boost conversion and AOV. Features OTP phone verification, A/B testing, multi-currency support, and event tracking across Facebook, TikTok, Google, Pinterest & Snapchat. Built as part of the Releasit team at Shop Circle. **Role:** Full Stack Developer - Part of Releasit — 150k+ active merchants across the app suite - Built for Shopify — Shopify's highest app quality tier Cash on delivery is how a large share of orders get paid for across the Middle East, North Africa, South Asia and Latin America — and Shopify's native checkout assumes a card. The app replaces that step with a single-page order form the merchant designs themselves: fields, layout, offers and copy, so a buyer can place an order in one click without ever reaching checkout. It runs as an embedded Shopify admin built in Remix and styled with Tailwind, using Polaris and App Bridge for the in-admin experience, while the buyer-facing form reaches the storefront through Liquid. Shopify data moves over both the GraphQL and REST Admin APIs, orders and configuration live in DynamoDB, and the service runs on AWS in Docker with CloudWatch for logs and alerting. Business logic is covered by Vitest. **Tech:** Remix, React, TypeScript, Node.js, Shopify API, App Bridge, Polaris, Liquid, GraphQL, REST, DynamoDB, AWS, Docker, CloudWatch, Vitest, Tailwind CSS **Detail page:** **Links:** [Shopify App Store](https://apps.shopify.com/releasit-cod-order-form) #### Releasit COD Fee & Verify — _Built for Shopify_ Set COD fees, discounts, and conditional rules by country, product, or order value. Verify orders with WhatsApp OTP to block fake checkouts and reduce RTO. Collect partial COD payments upfront with full payment tracking and balance visibility. Built as part of the Releasit team at Shop Circle. **Role:** Full Stack Developer - Part of Releasit — 150k+ active merchants across the app suite - Built for Shopify — Shopify's highest app quality tier Cash on delivery moves the risk onto the merchant: the order is placed before any money changes hands, so fake and impulse orders turn into returns to origin — stock shipped, courier paid, nothing collected. The app works on that from both ends, pricing the risk through conditional COD fees and removing it through verification before an order is accepted. Rules can key off country, product or order value, WhatsApp OTP confirms the buyer is real, and partial upfront payment turns a pure-COD order into one the merchant is already part-paid for, with the remaining balance tracked through to delivery. Same architecture as the order form it sits alongside: an embedded Remix admin on Polaris and App Bridge with Tailwind, Liquid on the storefront, Shopify's GraphQL and REST Admin APIs for data, DynamoDB for storage, and AWS with Docker and CloudWatch underneath. Tested with Vitest. **Tech:** Remix, React, TypeScript, Node.js, Shopify API, App Bridge, Polaris, Liquid, GraphQL, REST, DynamoDB, AWS, Docker, CloudWatch, Vitest, Tailwind CSS **Detail page:** **Links:** [Shopify App Store](https://apps.shopify.com/cash-on-delivery-fee) #### Releasit Bundles & Upsells — _Built for Shopify_ Product bundling app with quantity offers, related product upsells, cross-sells, and custom discount strategies to increase AOV. As Lead Project Developer I led the design, architecture, and build from scratch as part of the Releasit team at Shop Circle — with analytics, A/B testing, and highest-level Shopify compliancy. **Role:** Lead Project Developer - Designed, architected and shipped solo in under 6 weeks - Part of Releasit — 150k+ active merchants across the app suite - Meets Shopify's highest-level Built for Shopify requirements Bundling is one of the cheapest ways to raise average order value, but on Shopify it usually means choosing between a rigid native discount and an app that fights the theme. This one covers quantity breaks, related-product upsells and cross-sells with custom discount strategies, and puts analytics and A/B testing next to them so a merchant can tell which offers actually earn their place. I owned it end to end — the design, the architecture and the build. Remix and React in TypeScript for the app, Prisma over PostgreSQL with Redis and Node.js services behind it, hosted on Hetzner. Shopify data flows over GraphQL, and the storefront side renders through Liquid. **Tech:** Remix, React, TypeScript, Node.js, Prisma, PostgreSQL, Redis, GraphQL, Shopify, Liquid, Hetzner **Detail page:** **Links:** [Shopify App Store](https://apps.shopify.com/releasit-bundle) #### Releasit COD Form — Tiendanube Cash on Delivery order form for Tiendanube, one of Latin America's largest ecommerce platforms. Built natively on their stack rather than ported from Shopify — Nexo for the embedded admin, the Nimbus design system for the UI, and their REST Admin API throughout, following Tiendanube's own recommended app architecture. Built as Lead Project Developer on the Releasit team at Shop Circle. **Role:** Lead Project Developer Tiendanube is one of the largest ecommerce platforms in Latin America, a region where cash on delivery carries a real share of orders — but its app ecosystem works nothing like Shopify's. Rather than porting the Shopify app across, this one is built the way Tiendanube itself recommends: Nexo for the embedded admin, the Nimbus design system for the interface, and their REST Admin API for everything else. As Lead Project Developer I set the architecture and led the build. The MVP covers the form designer, quantity offers, a custom thank-you page, WhatsApp integration, shipping-rate handling, analytics, and Conversions API tracking for Meta and TikTok. React and TypeScript on the front, Node.js behind it. **Tech:** Tiendanube, Nexo, Nimbus, React, TypeScript, Node.js, REST API **Detail page:** _Currently in development — no public preview yet._ #### Releasit Support Platform Internal platform used daily by our CX and Support Developer teams to operate merchant stores at scale. Agents can navigate and edit any app install — its settings, database records, and integrations — inject custom CSS or JS that executes on the storefront, and copy full configurations between stores. Also recovers lost orders directly from CloudWatch logs. Built as part of the Releasit team at Shop Circle. **Role:** Full Stack Developer - Used daily by an 18-person CX and Support Developer team - Reaches any app install across the Releasit suite Support at this scale is a tooling problem. An agent working a merchant ticket needs to see the actual install — its settings, its records, what the storefront is really rendering — and usually needs to change something, without asking the merchant for collaborator access or queueing behind a developer. Around eighteen people across CX and Support Development work out of this tool every day. The platform gives them that directly: navigate and edit any install's settings and database records, inject custom CSS or JavaScript that executes on the storefront, copy a full configuration from one store to another, and recover lost orders straight out of CloudWatch logs. Built in Remix and React on Node.js, with DynamoDB behind it and the Shopify Admin API for store access. **Tech:** Remix, React, Node.js, DynamoDB, CloudWatch, Shopify API **Detail page:** _Internal tool — no public preview available._ ### Notable Side Projects #### Unmerciful — Guild Armory & Portal A full-stack platform for Unmerciful, a Horde PvP guild on Warmane's Icecrown realm - which I have been leading for the past 6 years. It pulls live server data into a public armory where anyone can look up a character's gear, stats, and arena history, or view them as a full 3D model. Members get their own space to claim characters and earn a guild rank, newcomers apply to join, and the whole guild can host, organise, and sign up for PvP events. Six years of leading a guild turned into a piece of software. The public half is an armory built on live server data: look up any character on the realm and see their gear, stats and arena history, or view the whole character as a 3D model in the browser. Behind the login it becomes the guild's operations tool. Members claim their characters and earn a rank, applicants submit and follow a join request, and the roster hosts, organises and signs up for PvP events. Next.js and React in TypeScript, with Supabase and PostgreSQL holding accounts and guild data, and the whole thing installable as a PWA so it behaves like an app on a phone. **Tech:** Next.js, React, TypeScript, Supabase, PostgreSQL, PWA **Detail page:** **Links:** [Live](https://unmerciful.app) #### WoW 3.3.5a PVP Addon All-in-one PVP addon for World of Warcraft 3.3.5a, built out of frustration after 15 years of running 20 separate addons just to play the game I love. Replaces my entire combat UI: custom unitframes (player, target, focus, arena), spell castbars with enemy cast tracking, cooldown timers for self and opponents, and diminishing-returns / CC tracking. Written in Lua on the Ace3 framework with XML UI definitions. Fifteen years of PvP on 3.3.5a means fifteen years of stitching together twenty addons that each do one thing, none of which agree on how they look or where they sit. This replaces that whole pile with one coherent combat UI. Custom unitframes for player, target, focus and arena; spell castbars that track enemy casts as well as your own; cooldown timers for both you and your opponents; and diminishing-returns and crowd-control tracking, which is what actually decides an arena game. Written in Lua on the Ace3 framework, with the interface laid out in XML against the 3.3.5a client API. **Tech:** Lua, Ace3, WoW API, XML **Detail page:** _Live link will follow once the addon is fully released._ #### Mini Shop Multi-tenant e-commerce platform inspired by Shopify — built from scratch to deeply understand how Shopify works under the hood. Full ecosystem including storefront rendering, tenant isolation, database architecture, logging, and error monitoring. The fastest way to understand a platform is to rebuild it. Mini Shop is a multi-tenant ecommerce platform written from scratch to learn how Shopify works underneath — not the app layer I work in daily, the platform layer beneath it. That meant solving the parts that are invisible from the outside: rendering a storefront per tenant, isolating tenants at the data layer, designing a schema that holds up when every row belongs to someone, and running logging and error monitoring across all of it. Next.js on DynamoDB and Redis, with CloudWatch and Sentry for observability. **Tech:** Next.js, DynamoDB, Redis, CloudWatch, Sentry **Detail page:** _Preview is not available._ #### Shopify Debug Extensions Chrome extensions built to enhance our support team's workflow — live storefront debugging, app diagnostics, and automated code changes directly from the browser. Support work on Shopify apps is mostly diagnosis: what is this storefront actually rendering, which app is fighting which, what does this install's configuration look like right now. These extensions put the answers in the browser next to the store instead of in a separate tool. Live storefront debugging, app diagnostics, and automated code changes applied straight from the browser — plain JavaScript against the Chrome extension APIs, built around how the support team actually works. **Tech:** JavaScript, Chrome APIs, CSS, Shopify **Detail page:** _Preview is not available._ #### Discord Automation Bot Discord bot with admin controls, scheduled messaging, game API integrations, and automated response systems. Hosted 24/7 via Railway. A bot that grew out of running a community rather than out of wanting to write a bot: admin controls for the people moderating, scheduled messaging so announcements do not depend on someone being awake, game API integrations that pull live data into the server, and automated responses for the questions that get asked every week. Built on Discord.js and Node.js, hosted 24/7 on Railway. **Tech:** JavaScript, Node.js, Discord.js, Railway **Detail page:** **Links:** [GitHub](https://github.com/MarioGit19/DiscordBot) #### Illuminate Web-Shop One of the first projects I ever built. E-commerce storefront with product filtering, cart drawer, streamlined checkout, and smooth UI transitions throughout the customer journey. Made in order to understand the flow of ecommerce and customer behavior/journey. One of the first things I ever built, and the reason the rest of my work looks the way it does. A storefront with product filtering, a cart drawer, a streamlined checkout and transitions that hold the flow together — made to understand how a customer actually moves from landing on a product to paying for it. That journey is the same one every Shopify app I have worked on since sits on top of, which is why it is still here. **Tech:** React, JavaScript, HTML5, CSS3 **Detail page:** **Links:** [Live](https://illuminate-mario.netlify.app/) · [GitHub](https://github.com/MarioGit19/Illuminate) ## Contact _Available for collaboration._ - **Location:** Sarajevo, Bosnia & Herzegovina · CET - **Email:** [mario.colic98@hotmail.com](mailto:mario.colic98@hotmail.com) - **WhatsApp:** [+387 62 883 196](https://wa.me/38762883196) - [GitHub (Personal)](https://github.com/MarioGit19) - [GitHub (Work)](https://github.com/Mario-Colic) - [LinkedIn](https://www.linkedin.com/in/mario-colic-23207a171/)