Nikola Jovanović · Full-stack engineer · Serbia
Software that makes business sense.
Full-stack engineering with a focus on sound architecture and real business goals. AI tools help the work move faster, and every change is still carefully reviewed and tested. More than a decade of work in fintech, e-commerce and research.
Approach
More than writing code
Code is only one part of a working product. Good results also depend on a sound overall design, a clear picture of the business, and careful use of AI tools.
Whole-system design
APIs, data models, background jobs, authentication and payments: how the pieces fit together, how they fail, and what they cost to run. Many past projects were carried end to end, from the first schema to production.
- phylogeny.app, designed and built solo
- Card platforms: onboarding, admin, APIs, legacy migration
- Current SaaS: FastAPI, Celery/Redis, Docker
Business goals first
Years of work in fintech, card issuing and multi-channel retail shape the approach: first understand what a feature should earn or save, then turn that into a scoped, realistic plan.
- Nine years of work with credit card companies
- Walmart, eBay & Sears marketplace integrations
- Long-term client partnerships since 2014
AI-assisted, reviewed
Claude Code, Codex and Copilot take on much of the drafting, a bit like a fast junior developer. Architecture, specs, review and testing stay in human hands, so speed doesn't come at the cost of quality.
- Claude Code, Codex & GitHub Copilot in daily use
- LLM features: RAG, semantic search, extraction
- Hosted and local models (OpenAI, Claude, Gemini)
About
The short version
More than ten years of designing, building and maintaining web applications: Laravel and Python back ends, Vue, React and TypeScript front ends, and a particular interest in data visualization and 3D.
Most of this work has come through long-term freelance partnerships, often covering a product end to end: credit card platforms and fintech tools, multi-marketplace e-commerce, startup MVPs and scientific software, including phylogeny.app, a phylogenetic visualization tool published in Nucleic Acids Research under its original name, Phylogeny.IO. The current focus is a B2B SaaS product built with FastAPI and React Three Fiber.
The priorities are clean, maintainable code, sensible trade-offs, and interfaces that stay out of the way. Outside of work: film production and photography (licensed drone operator), martial arts and improv theatre.
- Based in
- Serbia (CET) · working remotely
- Education
- MSc, Computer Science & Information Technologies — Faculty of Electronic Engineering, Niš
- Languages
- Serbian (native), English (fluent), Romanian (basic)
- Publication
- “Interactive Web-Based Visualization of Phylogenetic Trees Using Phylogeny.IO”, Nucleic Acids Research, 2019
Skills
Skills and tools
Architecture & systems
- REST API design & third-party integrations
- Data modeling — MySQL & PostgreSQL
- Async jobs & queues — Celery, Redis
- Auth & payments — OAuth2, JWT, Stripe
- Legacy modernization & data migrations
- Docker, CI/CD & Nginx deployments
Product & business
- Turning business goals into scoped plans
- MVPs and phased delivery for startups
- Fintech & card-issuing domain
- Multi-marketplace e-commerce
- UX/UI design & design systems (Figma)
- Accessibility (WCAG, ARIA)
AI-augmented engineering
- Claude Code, Codex & GitHub Copilot
- Spec-first prompting & review of AI output
- OpenAI, Claude & Gemini APIs, local models
- RAG, semantic search & structured extraction
Back end
Laravel · CodeIgniter · FastAPI · SQLAlchemy · Flask
Front end
Vue · Vuetify · React · TypeScript · Vite · Tailwind
Visualization & 3D
D3.js · Three.js · React Three Fiber · Highcharts · ApexCharts
Infra & workflow
Docker · GitHub Actions · Nginx · DigitalOcean · Git · Jira
Experience
Selected experience
Full-Stack Developer · Independent product
2026 – PresentRemote
A B2B SaaS product for e-commerce, currently in development, covering architecture, product decisions and delivery.
- Async FastAPI service with SQLAlchemy, Alembic migrations, Celery/Redis background jobs and JWT auth, containerized with Docker.
- React front end with an interactive 3D product viewer built on Three.js and React Three Fiber.
- AI-assisted workflow, with architecture and code review kept in human hands.
Python · FastAPI · React · Three.js · Docker
Senior Software Engineer · Wiser Technology
Nov 2025 – Aug 2026Niš, Serbia
Part of a 5–8 person team modernizing a long-running, business-critical platform without taking it offline for existing clients.
- Refactored legacy business logic in a custom PHP framework while still shipping new features and fixes.
- Gradually moved a mixed HTML/CSS and React front end toward a unified React shell, without a full rewrite.
- Rebuilt the core layout and shared design-system components during a rebrand.
PHP · MySQL · React
Full-Stack Web Developer · Freelance
May 2014 – PresentRemote
Long-term engagements with fintech, retail, startup and research clients, often covering the product end to end, from scope to production.
Fintech product for a startup
2024 – Present
An unreleased financial comparison and tracking product. Work on the Laravel API and the Vue/Vuetify interfaces behind it; details available on request.
Laravel · Vue · Vuetify · Tailwind · MySQL
Platforms for credit card companies
2015 – 2024
The systems card issuers use to acquire customers: onboarding portals, admin dashboards and REST APIs for card applications. Migrated legacy systems without compromising data integrity, and coordinated the companion mobile app's backend integration.
Laravel · CodeIgniter · Vue · Highcharts
E-commerce for appliance parts retailers
2016 – 2021
Walmart, eBay and Sears seller integrations that keep one inventory in sync across marketplaces, along with inventory and order logic and legacy modernization.
Laravel · Vue · MySQL
phylogeny.app — phylogenetic tree visualization
2015 – 2018
Designed and built solo, from data model to interface. Dendrograms, radial trees and cladograms in D3.js, shared annotations for research teams, and usage analytics. Published in Nucleic Acids Research (2019) under its original name, Phylogeny.IO.
Laravel · D3.js · MySQL
Also: startup MVPs (a sports portfolio platform and a mediator networking app), genomic data visualization with Python, Vue and D3.js, a React web app with an ASP.NET API for a cruise company, plus dashboards and marketing sites.
Web Developer · HTEC
Jun 2013 – May 2014Niš, Serbia
- Built an internal CMS with a strong focus on UI/UX.
- Contributed to a medium-scale travel application in a multidisciplinary team.
Laravel · MySQL · jQuery · Bootstrap
Web Developer · EtelSoft
Nov 2012 – Jun 2013Niš, Serbia
- Worked on international web projects across front end and back end.
- Contributed to UI/UX decisions and QA.
CodeIgniter · MySQL · jQuery
Clients
What clients are saying
“Throughout the project Nikola has taken remarkable initiative in all aspects of design and implementation, often suggesting innovative solutions to problems as they emerged. He is hands down one of the best people I've worked with.”
Alexander Mikheyev
Assistant Professor, OIST · Okinawa, Japan
“Nikola and I worked together on many development projects. He has always been dependable and conscientious. He is very easy to communicate with, and discuss tasks and ideas. I wouldn't hesitate to recommend Nikola for any project.”
David Barrington
Lead Developer, Appliance Factory Parts · New Zealand
“Nikola is the ideal freelancer. He follows instructions well and the final deliverable is prompt and exceeds expectations. I recommend you choose Nikola for your project.”
Mark Halloran
President and Developer, Highermedia Inc. · United States / Germany
“Nikola is an easy guy to work with. In-depth knowledge of D3.js. Excellent communication skills and fast to respond. 5 stars all round.”
Dr L. Heslop
CEO, Benchmark54 · Nottingham, United Kingdom