Dejan Velimirovic
Full-Stack Software Engineer
Part of FatCat Coders since:
August 2020
Dejan is an experienced software architect and engineer with over 19 years in web technologies. He excels in product development across healthcare, finance, and SaaS solutions, and has led complex software architecture projects. Dejan is a great fit for you if you are seeking highly adaptable, versatile engineer and architect that has DevOps expertise.
Calendly
WebpageJuly 2024 - ongoing
Calendly leads the way in automated meeting scheduling, offering team-based scheduling solutions and integrations with advanced security features.
Collaborated with a team of frontend engineers to develop a marketing webpage using
Next.js, styled-components, and Contentful as the CMS.
Utilized GitHub Actions to serve static files on an S3 bucket.
Designed and executed new A/B tests within the existing environment.
Participated in testing processes using Optimizely and Statsig, while conducting
analytics with Segment.Ensured robust and reliable code quality by writing end-to-end and automated tests
with Cypress and Jest.
Main tech stack:
Gatsby, Next.js, React.js, TypeScript, styled-components, Contentful, GitHub Actions, S3, Cypress, Jest, Optimizely, Statsig, Segment
Enjoy Good Health
e-CommerceJuly 2023 - July 2024
Clean and pure vitamin supplements are specifically designed for people who experience sinus and allergy problems.
As a Lead Engineer Architect, Dejan integrated Contentful CMS to enable flexible and efficient content updates, ensuring up-to-date product information, and engaging website content.
Assured secure and convenient monetary transactions through Stripe integration, fostering trust and minimizing checkout friction for customers.
Enhanced product additions by leveraging existing APIs and code from the admin panel, reducing development time and resource allocation.
Improved product listings and search engine visibility by integrating Google Merchant Center.
Established a modular and scalable architecture for future website growth and feature expansion.
Meticulously adhered to American data privacy regulations and relevant industry standards, building trust, and ensuring legal compliance.
Developed a custom user review system to encourage transparent feedback and build trust with potential buyers.
Worked within an e-commerce team alongside two additional developers, a product owner, two marketing managers, and a designer, following the Scrum methodology.
Developed a Strapi-based website to enhance the e-commerce site’s functionality, enabling content-rich experiences.
Main tech stack:
Gatsby (Vercel), Contentful, Strapi, Stripe
ProvideHealth
m-Commerce)February 2021 - ongoing
ProvideHealth is an App created by doctors that offers custom product selections for your health needs.
Implemented the Custom Provider Share Medication Recommendation Process with SMS Deep Linking using Twilio, providing personalized product suggestions based on user preferences, resulting in enhanced engagement and conversion rates.
Integrated Shippo to streamline shipping workflows, ensuring efficient order fulfillment and reliable, timely product delivery.
Improved user satisfaction with a smooth checkout process powered by Stripe for secure and convenient money transfers and subscriptions.
Ensured compliance of all integrated features with relevant industry regulations and data privacy laws.
Developed a robust admin panel, granting app owners complete control over purchases, metrics, product management (including item creation, classification, and inventory), and other critical operational aspects.
Led the development team, showcasing exceptional technical skills to resolve challenges and ensure app functionality and performance.
Optimized payment infrastructure for exclusive reach within the United States.
Worked within an m-commerce team alongside two additional developers, a product owner, a scrum master, and a designer adhering to the Scrum methodology.
Main tech stack:
Node.js (Nest.js), PostgreSQL, React.js, React Native, AWS, Stripe
Convertmore
WidgetAugust 2022 - December 2022
A customizable widget that helps you get more customers from your current website visitors.
Improved the Convertmore service by introducing new features and addressing bugs for a customizable widget designed to convert website visitors into customers.
Implemented features including support for Mexican phone numbers, tracking addition, account deletion, phone number spoofing, and analytics integration.
Resolved complex technical challenges as one of the most experienced and reliable engineers on the team.
Collaborated with the Covermore team, including the project manager and QA, to ensure seamless project execution.
Main tech stack:
Node.js, PostgreSQL, React.js, AWS
Badi.rs
Platform)January 2022 - ongoing
Badi.rs is B2B software designed for visualization purposes in Serbia. It is a modern platform for managing retail establishments and functions as an advanced Electronic Sales Invoice Registry (ESIR) system.
This project, led solely by Dejan, encompasses the entire development process from conceptualization and architecture to deployment and realization.
Badi boasts several key features of eFiscalization essentials, including product reporting system management, receipt exporting, and real-time stock management. Additionally, it seamlessly integrates with third-party services.
A notable aspect of Badi is its utilization of Golang to create the Electronic Sales Data Controls (ESDC) component. This unique feature communicates with a security element (a smart card with NFC) through a card reader to sign fiscal receipts, facilitating easy submission to the Serbian Tax Authority.
Badi is accessible across multiple platforms, including Windows, macOS, and Linux, and via web browsers on mobile devices. All features are fully supported on every platform. A mobile app version is currently under development.
Main tech stack:
Node.js, PostgreSQL, React.js, Electron, Golang
TradeCore
PlatformJanuary 2017 - February 2020
TradeCore is a platform-as-a-service provider that enables fintech to build next-generation banking and investment products.
Backend development for the trading service in the form of a platform accessible to other companies via API.
Leading the development of a mobile application tailored for trading cryptocurrencies.
Developing different features for the stock market web platform, including aggregating pricing data from multiple sources in real-time, facilitating optimal decision-making.
Establishing modular architecture allows for flexible integration with various platforms and stock markets through plugins.
Creation of native modules for Android and iOS, that were not predicted with React.js Native.
Over time, Dejan's role evolved to Lead Architect. Responsibilities expanded to include: planning and documenting various features, such as one for a real-time notification system utilizing Redis and custom Lua scripts to determine notification destinations.
Utilization of InfluxDB for fast data querying, particularly for low average prices within specified time intervals.
Worked in a team of two developers, whereas the other was working mostly on React.js Native and they had one designer.
Main tech stack:
Node.js, PostgreSQL, Redis, InfluxDB, AWS, React.js, React Native, Lua
ShiftPlanning / Humanity
SolutionSeptember 2011 - June 2016
ShiftPlanning is a B2B software solution for shift planning and workload coordination.
Initially involved in making smaller changes to the product during its final stages.
Played a key role in planning and developing a mobile web application from scratch to release.
Assumed high-level managerial responsibilities and collaborated closely with the hiring manager during the mobile app development phase.
Led the front-end development efforts, primarily focusing on building a single-page application (SPA) using JavaScript and Can.js.
Collaborated closely with the DevOps team to establish and update the product infrastructure, ensuring seamless operation across multiple servers.
The product initially couldn't operate on multiple servers. Consequently, they implemented database replication to enable multi-server functionality.
Main tech stack:
PHP, MySQL, JavaScript, Redis, Can.js
WayIDo
Social networkOctober 2009 - May 2011
WayIDo was a social network for creatives to showcase portfolios in various multimedia formats, such as videos, pictures, and music. Like Facebook, it featured features such as chatting, commenting, and interaction.
Conducted scraping and full migration from PHP to C++ backend, ensuring backward compatibility of old codes for use and adjustment in the new C++ backend.
Created proof of concept and compared performances between PHP and C++, resulting in the selection of an optimal solution.
Implemented a video chat feature within the webpage, utilizing a Flash component rewritten in JavaScript (Red5 server with Java backend).
Established a feature for the conversion of audio and video files into different formats, adjusting parameters such as size and resolution for compatibility with the social network.
Handled smaller DevOps tasks and other requirements.
Contributed to the introduction of functionalities in Redis, a key-value store, since the early stages of development.
Worked on writing a solution for a Redis Client in PHP, as one did not previously exist.
Led transition from using Memcached (simple key-value store) to Redis.
Collaborated within a team of 6 to 8 people, comprising 2 designers, 1 developer for databases, and 4-5 developers, with additional support from 1 DevOps engineer.
Main tech stack:
PHP, MySQL, JavaScript, Redis, C++, Java, Red5
MasCoders
WebpageMarch 2008 - September 2009
MasCoders was an outsourcing company for web page development in various industries and niches.
Primarily worked on web pages utilizing Drupal and Joomla frameworks.
Undertook a notable project involving the development of an Admin Panel resembling a C-panel for a hosting company, alongside a custom solution tailored for a Dutch company's hosting management needs.
Collaborated within a team of 5 to 6 full-stack developers to deliver projects efficiently.
Main tech stack:
PHP, JavaScript, MySQL, Drupal, Joomla
First Beat Media
SystemNovember 2005 - August 2008
First Beat Media was a web development company in the advertising and adult entertainment industry niche.
Implemented modifications to the internal advertising system, adapting ad formats for high-traffic web pages
Independently led the integration of a payment gateway.
Collaborated within a small team consisting of two developers and one manager.
Main tech stack:
PHP, MySQL, JavaScript
Masaryk University, Faculty of Informatics,
Brno, Czech Republic
- English - C1
- Czech - B1