Acko Spasic
Verified Expert in Engineering
Software Engineer and Full-stack Developer
Novi Sad, Vojvodina, Serbia
Toptal member since November 12, 2019
Acko is a highly talented software engineer with a proven history of working in the information technology and services industry. He has thorough knowledge and skills in JavaScript and TypeScript web programming (Node.js, React), as well as great communication and adaptation capabilities. Acko is a strong business development professional who leverages cutting-edge technologies for the best possible software solutions.
Portfolio
Experience
- Web Programming - 10 years
- JavaScript - 9 years
- Node.js - 7 years
- React - 6 years
- Socket.IO - 6 years
- Asynchronous Programming - 4 years
- TypeScript - 4 years
- REST - 3 years
Preferred Environment
Git, Linux, WordPress, WooCommerce, NGINX, Node.js, TypeScript, Web3, Solana, Ethereum
The most amazing...
...project I've been part of was developing enterprise businesses and websites that serve millions of users on a monthly basis.
Work Experience
Lead Senior Software Engineer / CTO
Freelance Clients
- I've led the team on developing the whole application from the grounds up, bringing it up from 0 users up to 100k+.
- Worked on optimizations allowing 500 parallel users using real-time features.
- Was responsible for fast response and reaction time in case of a bug or exploit on production.
Lead Full-Stack Developer / CTO
Freelance Clients
- Design and implement full system with user facing web app (PHP + HTMX), API service for clients setup (PHP), multiple microservice for different blockchain interactions (Node.js).
- Set up deployment infrastructure for the whole microservice structure.
- Worked on implementation of a multiple API versions, keeping the older version supported for a while due to having active users.
CTO
Freelance Clients
- Designed and developed a payment platform for credit card transactions, supporting Mastercard and Visa. Implemented secure processing, user-friendly interfaces, and compliance with industry standards for safe and efficient transactions.
- Managed a team of five to effectively implement a scalable software solution, fostering collaboration and ensuring project milestones were met. Focused on Agile methodologies to enhance productivity and deliver high-quality results.
- Oversaw the launch process that successfully handled over $100,000 in daily transaction volume. Ensured smooth operations, optimized workflows, and maintained system stability to support high-demand processing.
Senior Integration Developer
Bolt
- Developed a custom plugin to integrate Bolt Payment Gateway with WooCommerce on WordPress, enabling secure and effortless transactions. Focused on compatibility, ease of use, and smooth checkout experiences.
- Integrated the Bolt Payment Gateway plugin across 30+ high-traffic WooCommerce sites, handling millions of online orders. Ensured stability, scalability, and secure payment processing for reliable performance.
- Developed comprehensive unit tests for the entire application, ensuring code reliability and functionality.
Full-stack Developer
Ujamaa Marketplace LLC
- Developed a responsive landing page following Figma layouts, ensuring pixel-perfect design alignment. Focused on user-friendly interactions and optimized load times for a smooth user experience.
- Set up the foundational structure of a Next.js application, establishing routing, server-side rendering, and optimized configuration to enhance performance and scalability.
- Implemented page load optimizations to improve performance, including code splitting, image compression, and caching strategies. Enhanced speed and responsiveness for a better user experience.
Front-end Web Developer
Emvisage
- Worked on building and maintaining the front-end web application.
- Worked on building and maintaining multiple private libraries.
- Designed the front-end code structure and participated in the decision-making process regarding technologies and design patterns used.
- Led the complete refactoring of project technologies and set up processes.
- Participation in building the system from the ground up.
Front-end Developer
Ergofy Limited
- Refactored an existing application to use best practices and newer libraries and cleaned up the codebase from unnecessary or redundant code.
- Forked a JSON: API serialization/deserialization library and fixed some issues in order to properly connect the front end with a server.
- Implemented missing pages and functionalities following best practices and DRY code principles.
Back-end Developer
CSGOEMPIRE
- Designed and implemented RESTful API endpoints to support multiple front-end applications, ensuring seamless data flow, scalability, and efficient communication between the client and server.
- Integrated the application with the Steam API, enabling seamless data retrieval and functionality from the third-party platform. Streamlined communication and ensured compatibility for a cohesive user experience.
- Created real-time communication support through WebSockets (Socket.IO).
Full-stack Web Developer
Kolosek
- Created full-stack and RESTful API applications using Ruby on Rails.
- Developed and optimized front-end applications using React, focusing on user interface design and performance. Collaborated with cross-functional teams to enhance user experience and ensure responsive, efficient web applications.
- Managed server administration for Linux machines, including configuration, monitoring, and troubleshooting. Ensured system security and optimized performance for reliable, high-availability environments.
- Mentored a batch of interns, providing guidance on projects, technical skills, and best practices. Supported their learning and growth, helping them build foundational skills for future roles.
- Implemented a lot of custom designs and design updates using HTML, CSS, SASS, and LESS.
Experience
HTMX adapter for Laravel 11+
https://github.com/Ex-Nihilo-Ltd/laravel-htmxUjamaa Marketplace
https://ujamaa.digital/ArkPay
http://arkpay.comBolt.com: Payment Gateway
Emvisage
https://www.emvisage.com/CSGO Gambling Site
Education
Master's Degree in Electrical and Computer Engineering
Faculty of Technical Sciences - Novi Sad, Serbia
Bachelor's Degree in Electrical and Computer Engineering
Faculty of Technical Sciences - Novi Sad, Serbia
Skills
Libraries/APIs
React, Node.js, React Router, Stripe API, REST APIs, WordPress API, Claude API, React Redux, Socket.IO, Redux-Saga, Steam Web API, Steam Integration, JSON API, LocalStorage, Passport.js, React-Intl, WooCommerce API, HTMX
Tools
WebStorm, Git, GitHub, NPM, GitLab, NGINX, PageSpeed, Claude Code, Claude, Claude Agent SDK, Notion, Sequelize, AWS Command Line Interface (CLI)
Languages
JavaScript, TypeScript, PHP, SQL, HTML, CSS, Less, Sass, Python, Java, C, C++, Ruby, TypeScript 5, PHP 8
Frameworks
Express.js, Laravel 8, Vanilla JS, Next.js, NestJS, Jest, Ruby on Rails (RoR), Hapi.js, Cypress, Laravel 11
Paradigms
REST, Asynchronous Programming, Microservices, Design Patterns, Functional Programming, Real-time Systems, DevOps
Platforms
Linux, Ubuntu, WordPress, WooCommerce, WordPress VIP, Amazon Web Services (AWS), Blockchain, Steam, Windows, CentOS, Software Design Patterns, Amazon, Ethereum
Storage
MySQL, PostgreSQL, MongoDB, Amazon S3 (AWS S3), IndexedDB, Databases, Redis
Other
Async/Await, Web Programming, Algorithms, Front-end, APIs, Payment Gateways, Architecture, Back-end, WebSockets, CTO, Large-scale Projects, Full-stack Development, Landing Page Optimization, Web Scraping, Website Data Scraping, Payment APIs, API Integration, Full-stack, Web Development, Web3, Solana, IT Security, JavaScript Libraries, Google SEO, Vibe Coding, Supabase, AI-generated Code, JetBrains IDE, Axios, Lint, Bcrypt, Validation, Data Structures, Software Development, Software, Websites, Lovable, Cloudflare, Message Queues, Background Jobs
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