Full-stack Developer in Belgrade, Serbia

iOS application developed using Flutter framework, which is designed to be used by patients who have heart diseases to help them adapt their lifestyle to feel better. The app doesn't have an associated first-party back-end, and it uses Firebase and its Cloud Firestore for storing content in a NoSQL way. I worked as a solo front-end developer, defining app architecture from scratch and focusing on its robustness. Hence, its front-end has a "mini back-end" in separate Flutter modules.

The look and feel of the app rely on the Figma prototype. The app's core is the Get design pattern and state management system (https://pub.dev/packages/get), and it's very suitable for creating reusable and generic portions of the code, which can be implemented easily in some other application environments. The app is accessible only to subscribers registered into RevenueCat back-end using Apple Store in-app purchase mechanism.

After subscribing, users have access to health tests, daily/weekly tasks, and health data (integrated Apple Health Kit). Based on their daily activity, the app calculates scores using very complex calculations to present users real state of their bodies.

Boost website is one of the samsung.com services, which is available in the United Kingdom and Ireland as two separate web applications using the common back-end. The project was designed to detect users' mobile devices - https://samsung.com/uk/boost and https://samsung.com/ie/boost pages, to serve them partner offers and promotions by generating voucher codes. Official partners generate voucher codes - Deezer, Calm, YouTube Premium, Readly, Google Play Pass, Google Play Points, Adobe Lightroom, Disney+, Fiit, and Antstream.

The app's front-end was developed using React framework, and the back-end was implemented in Node.js, while MongoDB is used on the database side. I led a team of two developers and a QA engineer as a technical project manager with some support in development and deployment.

Some of the features are:
• Samsung Account Social Sign In
• ReCaptcha Enterprise
• Device detection (eligible devices - S21 Series, Flip, Fold, Tab S7, Desktop)
• Country detection (used third-party API - https://ipdata.co/pricing.html)
• Integration of new partners (Disney+) and their voucher codes

Back-end deployment requires Kubernetes and Helm usage; Front depends on Adobe Experience Manager.

This web application offers users with a non-Samsung device to buy its Samsung alternative in the same class (main targets are Apple and Huawei). It was developed for the Adriatic region. Its core feature is the device brand and model recognition algorithm based on user-agent and third-party libraries. This system has an admin panel with content management features, where the admin can define products, offer contents, partners, and target groups for detection. Based on the detected target group, the relevant competitor's website is rendered, and the user can be redirected through it to the partners' shops. Partners are lead technical retailers in Serbia.

I led a team of two software engineers who delivered the product, and I was responsible for communication with the client and partners. Competitors' platform offers its API for redeeming voucher codes and tracking sales on partner's websites. Partners can sign in to their admin panel and track their vouchers.

Project is implemented in Laravel (MVC + API) with front-end stack - HTML, CSS, JavaScript, Bootstrap. MySQL is used as a database server. I set up CI/CD with Docker and self-hosted Gitlab.

Flutter application developed for the biggest food retail company in Serbia (MAXI - https://maxi.rs) which is the part of the huge global retail group - Ahold Delhaize (https://www.aholddelhaize.com). The goal of the app was to perform online giveaways through puzzle games and augmented reality features. I was responsible for front-end development, while API endpoints were implemented in parallel by another development team.

The application consists of an integrated puzzle game built using the Unity framework. Besides that, there is an interactive map filled with markers on the territory of Serbia, generated by a specific algorithm that takes into the account user's location and location of all retail stores in the country. Map markers are representing gift boxes that can be collected by using the Augmented Reality feature. Gift boxes are used for getting giveaway products from stores and for getting additional lives for the game.

From the additional features, the app used Firebase Dynamic Links and Push Notifications. I was providing weekly builds to be tested by the end company using Firebase Distribution and Test Flight.

Customer website and admin panel feature updates for the biggest cryptocurrency exchange in Serbia. I was responsible for the back-end development of APIs (in Laravel) used by the customer website, which was developed in parallel by another team member. Also, I had full-stack tasks on Admin Panel, which has MVC architecture - back end built in FuelPHP framework, and front in HTML, CSS, and JavaScript.

The tasks which I worked on were related to two big features:
1. Automatic handling of weekly transaction limits and user risk levels.
2. Creation of secure Crypto and Fiat wallets integrated with third-party systems

These features had related tasks that needed to be implemented both on the admin panel and customer websites.

When the first feature was implemented, it reduced the amount of manual work which operators previously performed. It provided support for uploading various personal documents used and processed by finance institutions of the countries where the site was deployed (Serbia, North Macedonia, and Australia).

Wallet development upgraded company, which only had Crypto-Fiat centralized exchange feature to the trading ecosystem with personal wallets, where customers can hold Crypto/Fiat. Implemented MFA/reCAPTCHA.

A web platform which sells guest posts on high authority websites with solid metrics and traffic stats. These websites cover a wide variety of niches including finance, education, gambling, travel, health, and much more. Unlike some other link building providers, Authority Builders provides links from trusted, real ranking websites.

I am the head of the tech team, who is responsible for leading a group of six software engineers. My team is working together in the office and provide remote outsourcing for Authority Builders Co. Besides managing the team, I am working on core system stuff and collaborating with projects managers, sales, finance teams, and founders.

The project consists of four web portals which are organized as separate web applications: Customer, administrator, blogger, and content writer portals. Web applications based on MVC and API architecture use the CodeIgniter framework. My team is working on developing new features, improving existing functionalities, code optimization, front-end upgrades, and more. The most important part of the back-end stack is developing and integrating payment systems (PayPal, Stripe APIs), which are directly affecting the income of Authority Builders Co.

A social app that allows groups to decide where they want to eat. It utilizes a gesture-based user interface for finding nearby restaurants and bars in the US. The idea behind the app is to remove the back and forth discussions between groups by automating the decision-making process with a unique preference system.

I was responsible for implementing a complete Flutter app based on the Invision prototype that the designer provided. I collaborated with a back-end developer who prepared an API for which I integrated endpoint calls and data flow on the front end.

The app uses a location feature to select an area of interest for a group, a smart push notification system that keeps the app synchronized in real-time and deep links that allow new users to join the eating decision process easily.

I implemented a lot of animations on different screens, which makes the gesture-driven interface more powerful. I also deployed the beta version of Android and iOS apps in the Play Store and App Store.

Multiple dating websites for more than 10 countries in their native languages worldwide, backed by a multi-functional Admin platform with both common and separated data for all websites. Websites and admin panels are implemented in Laravel with a standard front-end tech stack (HTML, CSS, JavaScript). The purpose of the websites is to attract customers to buy credits to send messages to "fantasy" girls on whose behalf operators respond to them. Operators have their supervisors and can sign in to the admin panel for a specific country, where they have historical stats and different parameters for evaluation of their work.

Responsibilities:
• Payment integrations (RocketGate, PaysafeCard, CCBill)
• Marketing platform integration (Everflow)
• Scraping content from websites that are global leaders in the dating industry
• Creating automatic backup mechanisms for database and file system which counted more than 1TB of data
• Automatic deployment mechanisms with the possibility for real-time production fixes
• New features which led to huge revenue growth in a few months

Managed both ends, database and web servers.

Fork of SuiteCRM system with many new features implemented to satisfy requirements for managing and presenting data from the warehouse of Payment1 Loan company (https://payment1.com). All extensions to the existing CRM system were developed using pure PHP programming language and MySQL database (back end), and data representation were implemented using standard front-end tech stack - JavaScript, HTML, and CSS.

I was responsible for full-stack development and DevOps on the CRM's side. I had intensive communication with the tech team, which maintained Payment1 Loan data warehouse storage and their presentation site (https://payment1.com).

Some of my achievements were:
• Creating automatic Bash Script for daily importing of users, payments, loans from the data warehouse to the newly created CRM system (Bash Script with periodical SFTP connection).
• Writing high-quality MySQL raw queries to extract all necessary stats from the CRM to present them to the employees who are using it.
• Tracking complete user behavior with a specific algorithm and monitoring their activity, average time spent, and recording sign-up conversions from various referrers.
• Setting up an email server to support campaigns.

A cross-platform app that was developed using the Flutter framework for Dart programming language. The purpose of the app was to connect subscribed clients with their favorite personal trainers, via online video workouts and exercises during lock-down, caused by the COVID-19 virus.

I was responsible for all parts of this project including the Flutter app, Laravel API (MySQL database), and Laravel MVC admin panel. I worked as a developer who needs to fix all design and functionality issues made by developers who worked on this project from start. I also redesigned and reimplemented all parts of this project, including refactoring code structure and creating reusable design patterns. Implemented functionalities like social login, subscriptions, search, feed, favorites, and profile.

I localized both sides of the app (front-end and back-end localization) to Arabic and English. I also deployed test versions of Android and iOS App to the Google Play Store (production) and App Store (test flights).

• Developed a cross-platform (iOS, Android) app using the Flutter framework and the Dart programming language.
• Built a back-end REST API which was implemented using Spring Boot in Java. The data layer is accessed via PostgreSQL.
• Implemented a Firebase API (for authentication) and Google Cloud Services (Firestore and Google Cloud Storage).
• Developed an admin platform in PHP using the Laravel framework which connects to the same PostgreSQL database.

I was responsible for all parts of the project (excluding app design and deployment). The mobile app includes a subset of standard social network features (like a simple version of Instagram) including posts, likes, comments, followings, chat, and notifications. I also implemented additional functionalities like makeover courses and lessons (that content is uploaded through the admin panel). I used Google Cloud Storage to store social network media content (videos, images, and lessons). The chat and notification subsystem was implemented using Google Firestore with Firebase-based user authentication.

This is an application which communicates with third-party APIs which provide COVID-19 Stats for the US, locations of test centers, test results, business events, QR code ticket scanning, geolocation features, and other stuff to help fight this disease

As a full-stack developer, I implemented it from scratch. I was also responsible for the Flutter app which communicates with the REST API, which I implemented using Spring Boot in Java and PostgreSQL database, and third-party APIs for tracking virus statistics. I was also responsible for the deployment of the app to Google Play Store and App Store (Test Flight).

I implemented a decentralized web platform for secure file sharing between users.

It's based on Ethereum smart contracts and the InterPlanetary File System (IPFS). I built the front end using the JavaScript API for the Ethereum blockchain and IPFS and executed the back-end code only within the smart contracts, which are implemented using Solidity. A central server doesn't exist in the application at all. That system has a futuristic concept for file sharing without the presence of a third-party server.

I established a connection with Ethereum network using the Metamask extension for the Google Chrome browser. The main innovation, which the implementation of this system provides, is the protection of file content located on IPFS network. The files are protected using symmetric-key cryptography and related keys for protection are encrypted with public/private keypair.

I developed that system as an individual project which means that I was responsible for the front end and back end of this decentralized web application.

I implemented an admin sales management platform for sophisticated and semi-complex web stores.

It allows the manipulation of products, categories, brands, coupons, vouchers, invoices, suppliers, orders, and more. In addition to selling, there is also an option to add new text articles to the company blog. Various statistical parameters are also available (based on sales trends), and stock balances can be tracked as well as the distribution of products in any single shop.

It can be integrated into any client's website because it is entirely independent of the particular sales company. There are also multiple user groups in the system with different degrees of privileges. We built it for the Serbian market, and several online sales companies are currently using it. As the platform facilitates a large volume of sales, so much of the paperwork is automated, which saves a significant amount of time for shop administrators.

The platform was implemented using the Laravel framework and MySQL database. The front end was built using the Bootstrap library along with standard technologies like HTML, CSS, JavaScript, and jQuery.

I developed a mobile and web application which connects blue-collar workers—like mechanics, plumbers, electricians, and so on—with clients who in need of their services. The way it works is people who are looking for work provide advertisements for the work that they are capable of doing and the clients peruse them.

I was responsible for creating and filling out the GUI components for desktop (JavaFX framework) and mobile application (Android Studio) based on a previously defined prototype.

I developed a web app's back end. The app's primary purpose is to connect teachers with students along with providing support for booking private lessons and payment exchanges. The tutors advertise which university courses they can help in as well as their pricing.

I developed a REST API (using the Laravel framework) and coded REST services for authentication, class booking, and more. I also built models that are responsible for managing MySQL database entities.

The project is intended, above all, to be a website and webshop of a company that has been a leading seller, importer, and distributor of audio equipment in Belgrade for 20 years. The company represents only world-renowned audio brands, and it is the exclusive importer of them for the Republic of Serbia. It also specializes in all facilities where music is an indispensable element of everyday events.

It is an advanced eCommerce website that is implemented in the Laravel framework using a MySQL database as a data storage. The site has an MVC architecture, and I built the front end using the Bootstrap library along with standard technologies like HTML, CSS, JavaScript, and jQuery. The developed website includes several different user groups, as well as an admin platform through which it is possible to manage the content of the web-store.

I was responsible for the implementation of the entire website.

I completely developed the front end and back end of a ticket reservation website for a film festival with a large number of screenings over several days in different projection halls.

I implemented the site using Java Server Faces (PrimeFaces library) and connected the MySQL database entities using JDBC and JPA. The web application also has an MVC architecture type.

I developed the entire front end and back end of a website that hosts recorded classes for many courses at the University of Belgrade, School of Electrical Engineering.

The site is beneficial to students in their exam preparation. The audio recordings are divided by university levels, sections, and exam titles, and they are playable through a website-embedded audio player. All of the audio files were stored with compression on a central server, and we used a database to index them.

Along with implementing the MVC architecture in the app, I built the back end using the Laravel framework and the front end using JavaScript, jQuery, Ajax, HTML, CSS, and Bootstrap.

I developed a console application for synchronizing, controlling, and validating shop transactions between multiple client programs. It's implemented in Java, using Java Message Service and Glassfish server for remote messaging. We stored all transaction data inside a MySQL database, which is accessible via a Hibernate framework.

I developed this Android game in Java using Android Studio.

The game provides three playing modes: single-player mode against a bot, multiplayer split-screen mode, and spectator mode with two bots playing as opponents. To roll the dice, data is collected from physical device sensors.

I also implemented three difficulty bot levels using artificial intelligence. An SQLite database stores all of the saved games and history of results.

The game implementation consists of two components: server and client.

The server component represents the game supervisor, and client components are the players playing the game as opponents. Communication between clients and server was implemented in Java using Sockets, and there is support for both LAN and WAN game lobbies.

I was responsible for both developing the game in Java and creating a graphical user interface (GUI) using the Java Swing library.

I developed an Android game that implements the physics of a ball bouncing and accelerating. It is a single-player game that was built in Android Studio, using the Java programming language.