Tomislav Krnic, Developer in Ghent, Belgium
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Tomislav Krnic

Verified Expert  in Engineering

Bio

Tomislav is a full-stack developer and designer with 20+ years of experience, specializing in unique mobile app and web solutions. A founder and co-founder of several businesses, he has delivered 50+ major projects, including impactful solutions for visionary founders with unique ideas. Since joining Toptal in 2012, Tomislav has focused on building practical, high-value applications, helping entrepreneurs bring problem-solving innovations to life.

Portfolio

MeaMate
Full-stack Development, React, React Native, APIs, Big Data, Location Services...
CityX Apps
Firebase, React Native, iOS, Android, React, APIs, Card Payments, Payment APIs...
Krnic CommV
React, Node.js, Firebase, OpenAI, Firebase Cloud Functions, Scraping, ChatGPT...

Experience

  • User Interface (UI) - 20 years
  • Startups - 20 years
  • Full-stack - 15 years
  • React - 7 years
  • React Native - 7 years
  • Mobile Applications - 7 years
  • Firebase - 7 years
  • ChatGPT - 2 years

Availability

Part-time

Preferred Environment

React Native, Firebase, Startups, Full-stack, React, UI Development, Web Development, Mobile/Web Project Management, Payment APIs, ChatGPT

The most amazing...

...thing is seeing people ordering food, paying bills, checking city news, and planning fishing trips—all with apps I built to simplify their lives.

Work Experience

Co-founder | Lead Developer

2024 - PRESENT
MeaMate
  • Built MealMate from scratch as a powerful SaaS platform for restaurants and point of sale (POS) providers, streamlining ordering, payments, in-store ordering, and delivery to solve operational challenges with custom technology.
  • Researched the current state of restaurants and bars, leveraging prior success, an award, and a notable exit in this market. Identified common challenges affecting non-global chain restaurants, revealing clear opportunities for improvement.
  • Designed the full architecture, brand identity, and logo, reflecting innovation and reliability, with a visual message emphasizing simplicity and efficiency to align with the platform's technical focus.
  • Created a iOS and Android mobile app in React Native and integrated it with Firebase to provide a comprehensive food ordering solution featuring location-based services, advanced menu options, payments, loyalty programs, and order tracking.
  • Built a comprehensive content management system (CMS) in React to give restaurants full control over their operations and enable POS providers to manage restaurant processes efficiently.
  • Designed and built a web-based restaurant terminal to accept and manage orders, track working hours, and provide information on available delivery personnel, ensuring efficient real-time management.
  • Built a comprehensive API solution with over 50 endpoints publicly available for POS providers, ensuring high security, validation processes, error tracking, and log analytics. The system operates in three modes: production, test, and development.
  • Developed an in-store ordering system, including repeat order and split bill features, with QR and NFC table sticker solutions, enabling customers to order inside the restaurant. It is the mobile app and a standalone web solution.
  • Developed modules for delivery tracking, payment integration, issue escalation, delivery time estimation based on real data, and various integrations to ensure full functionality. Collaborated with a colleague on this project.
Technologies: Full-stack Development, React, React Native, APIs, Big Data, Location Services, Payment APIs, Card Payments, HTML, API Design, GitHub, Apps, App Design, Technical Leadership, NoSQL, Node.js, App Store, Google Play Store, Leadership, Architecture, AI Automation, OpenAI API, Python, Maps, JSON, Redux, Express.js, Cloud Firestore, Google Maps API, Mobile Apps, AI Chatbots, Git, Large Language Models (LLMs), API Integration, Expo

Founder

2019 - PRESENT
CityX Apps
  • Acted as the founder and CTO of CityX, a company specializing in smart city app solutions. The app is available in over 50 cities and 12 countries and has been translated into 10 languages. The app consists of a collection of APIs and open data.
  • Found answers to questions on how to make the biggest app in a smart city space. Brought the idea to life, including contributing to designing the system architecture, leading developers, and creating the entire UI/UX.
  • Delivered the CityX app, a fully functional application available in stores. Many AI solutions have reduced the need for an oversized team. Quarterly growth is approximately 200%.
  • Utilized my skills, encompassing React Native, Firebase, React, Node.js, UI/UX, Google Cloud, payment solutions, tons of API integrations, and cloud functions.
  • Created an MVP app that serves as a solunar forecast for anglers and has an integrated map with the option of live streaming fishing and positions. With integrated AI, the application recognizes the type of fish from the photos.
Technologies: Firebase, React Native, iOS, Android, React, APIs, Card Payments, Payment APIs, Node.js, Mobile Design, User Interface (UI), User Experience (UX), Full-stack, UI Design, Google Cloud Platform (GCP), Mobile Development, Startups, Web & Mobile Applications, Cross-platform, Front-end Development, Mobile UI, Mobile UX, Mobile, Push Notifications, REST APIs, TypeScript, Live Chat, Mobile Applications, ChatGPT, Full-stack Development, Artificial Intelligence (AI), OpenAI, App UI, App UX, UX Design, Azure, API Design, GitHub, Apps, App Design, Technical Leadership, NoSQL, App Store, Google Play Store, Leadership, Architecture, Web Scraping, AI Automation, OpenAI API, Python, Maps, JSON, Redux, Express.js, Cloud Firestore, Google Maps API, Mobile Apps, AI Chatbots, Git, Large Language Models (LLMs), API Integration, Expo

Full-stack Developer

2024 - 2025
Krnic CommV
  • Developed an AI-powered content generator within Origami Social that auto-creates multi-platform posts, analyzes engagement metrics, and refines future content, boosting efficiency for social media managers.
  • Implemented a machine learning module to intelligently respond to user comments, track performance trends, and recommend post improvements.
  • Engineered a data-driven pipeline that dynamically adjusts campaign strategies based on real-time engagement insights, creating a scalable, automated social content optimization framework.
Technologies: React, Node.js, Firebase, OpenAI, Firebase Cloud Functions, Scraping, ChatGPT, APIs, Payment APIs, Stripe, Stripe API, Web Scraping, AI Automation, OpenAI API, Python, Maps, JSON, Redux, Express.js, Cloud Firestore, Mobile Apps, Git, Large Language Models (LLMs), API Integration

Full-stack Developer

2024 - 2024
Fishing Pro - Fishing App
  • Developed Fishing Pro, an app for anglers utilizing AI to predict fish activity based on solunar theory. The app offers real-time weather updates and a tracker for fishing spots, enhancing trip planning and improving results.
  • Developed an advanced system that tracks 15+ data points for accurate fish activity predictions. Implemented a fishing tracker that helps users log catches and optimize their trips, improving user engagement and app retention rates.
  • Launched Fishing Pro, generating several hundred dollars per month in subscriptions within the first months. Led the app's development from scratch, achieving rapid user growth and establishing a foundation for future expansion.
Technologies: React Native, Firebase, APIs, UX Design, UI Design, Full-stack Development, API Design, GitHub, Apps, App Design, Technical Leadership, NoSQL, Node.js, App Store, Google Play Store, Leadership, Architecture, Web Scraping, AI Automation, OpenAI API, Maps, JSON, Redux, Express.js, Cloud Firestore, Google Maps API, Mobile Apps, AI Chatbots, Git, Large Language Models (LLMs), API Integration

Full-stack Developer - React Native Mobile

2023 - 2023
Yahn Enterprises, LLC
  • Developed a mobile application within the planned timeframe, from a client's idea into a fully functional product ready for user acquisition.
  • Performed full-stack development, UI/UX, and logo design.
  • Built the application with React Native and Firebase. The app is published in App Store.
Technologies: React Native, Firebase, iOS, Android, Mobile UI, Mobile UX, Startup Consulting, Full-stack Development, GitHub, Apps, App Design, Technical Leadership, App Store, Google Play Store, Architecture, JSON, Git, API Integration

Full-stack Mobile Developer

2020 - 2022
Entrio
  • Developed a mobile app from Entrio, the most prominent Croatian event-ticketing company with over 1,200 events per year and over 280,000 tickets.
  • Built a React Native application from scratch that was intended as a ticket scanner connected to a few servers with non-SQL and SQL databases.
  • Contributed to developing the React Native application that consisted of multiple solutions, including communication between scanners, offline mode, and tons of logs. Event organizers could hire Entrio to ensure a smooth process.
Technologies: React Native, UI Design, UX Design, Firebase, Firebase Realtime Database, APIs, Scanning, Ticketing, Ticket Systems, Events, Event Ticketing, SQL, SQLite, Amazon Web Services (AWS), Google Cloud Platform (GCP), Figma, Mobile Development, Front-end Development, Mobile App Development, Mobile UI, Mobile UX, Mobile, Push Notifications, REST APIs, TypeScript, Cross-platform, Mobile Applications, Full-stack Development, PostgreSQL, API Design, GitHub, Apps, App Design, Technical Leadership, NoSQL, App Store, Google Play Store, Leadership, Architecture, JSON, Redux, Cloud Firestore, Mobile Apps, Git, API Integration

Co-founder | CTO and Full-stack Mobile Developer

2018 - 2020
Grga
  • Worked on Grga, a mobile application for payment and ordering processes related to restaurants and bars. The app provides a solution for connecting to more than 50,000 cash registers. One solution enables users to make orders and pay with a QR code.
  • Designed a system, created a mobile app and the UI/UX and connected with the payment gateway. Worked on it for a little over two years; millions were paid without any mistakes or wrong orders, and I have a reason to be satisfied with the project.
  • Completed the project and after a successful exit, Grga still exists within a large multinational company.
Technologies: Firebase, React Native, CSS, iOS, Android, Payment APIs, Credit Card Processing, User Interface (UI), User Experience (UX), Full-stack, UI Design, Amazon Web Services (AWS), Google Cloud Platform (GCP), Mobile Development, Startups, Front-end Development, Mobile App Development, Mobile UI, Mobile UX, Mobile, Push Notifications, REST APIs, TypeScript, Cross-platform, Mobile Applications, Full-stack Development, PostgreSQL, API Design, GitHub, Apps, App Design, Technical Leadership, NoSQL, App Store, Google Play Store, Leadership, Architecture, JSON, Redux, Cloud Firestore, Mobile Apps, Git, API Integration

Co-founder and Senior Full-stack Developer

2015 - 2018
Touchmoon
  • Created an application for Touchmoon, a demanding project that aimed to represent a new generation of mobile messengers. The application has multiple unique solutions and features like animations, strong security, and custom games.
  • Created the functional UI/UX and the web part of the project.
  • Delivered Touchmoon, the app had a good start, excellent reviews, and was mentioned in the media.
Technologies: React, React Native, PHP, MySQL, APIs, HTML5, CSS, Design, Firebase, User Interface (UI), User Experience (UX), Full-stack, UI Design, Amazon Web Services (AWS), Google Cloud Platform (GCP), Startups, Front-end Development, Mobile App Development, Mobile UI, Mobile UX, Mobile, Push Notifications, REST APIs, Live Chat, Mobile Applications, Full-stack Development, HTML, PostgreSQL, Azure, API Design, GitHub, Apps, Technical Leadership, App Store, Leadership, Architecture, JSON, Cloud Firestore, Git, API Integration

Senior Front-end Developer

2012 - 2016
FragranceX
  • Developed the front end and responsive design as my role for the project.
  • Worked for FragranceX, one of the biggest US-based eCommerce stores. Every "pixel" on the web was important, and my focus on details came to the fore.
  • Optimized the user interface and experience; developed the JavaScript front-end solutions and created a fully responsive web.
Technologies: HTML5, Sass, CSS, jQuery, JavaScript, User Interface (UI), User Experience (UX), Full-stack, UI Design, Front-end Development, REST APIs, Full-stack Development, HTML, PostgreSQL, GitHub, Technical Leadership, Architecture, JSON, Git, API Integration

Experience

CityX

http://www.cityx.hr
CityX is an ultra‑urban civic innovation app offering dozens of interactive city widgets, including transit, traffic, air quality, parking availability, local events, weather forecasts, restaurant recommendations, public art maps, safety alerts, and more. The system leverages IoT sensors, real‑time data streams, and AI‑driven analytics to enhance urban living. It supports 12 languages and operates across 15 countries and nearly 100 cities in Europe, making it the world's largest network of cities.

Education

2001 - 2005

Bachelor's Degree in IT Engineering

Polytechnic University of Zagreb - Zagreb, Croatia

Skills

Libraries/APIs

Google Maps API, jQuery, API Development, React, Node.js, REST APIs, Mapbox API, Stripe, Stripe API, OpenAI API, Google Maps, Facebook API, X (formerly Twitter) API, Amazon FPS

Tools

Adobe Photoshop, ChatGPT, GitHub, Expo, Adobe Illustrator, Figma, Git

Languages

PHP, HTML5, Sass, CSS, JavaScript, HTML, SQL, TypeScript, CSS3, Python

Frameworks

React Native, Redux, Express.js, Smarty, Next.js

Paradigms

UX Design, Mobile Design, UI Design, Mobile Development, Cross-platform

Platforms

Firebase, Google Cloud Platform (GCP), Mobile, Mapbox, iOS, Android, Amazon Web Services (AWS), Azure

Industry Expertise

Web Design

Storage

JSON, MySQL, Firebase Realtime Database, PostgreSQL, NoSQL, Cloud Firestore, SQLite

Other

Pixel Perfect, Graphic Design, Ajax, User Interface (UI), Icon Design, APIs, Web Development, Front-end, Front-end Development, User Experience (UX), Software Development, Full-stack, Startups, Card Payments, Payment APIs, Credit Card Processing, Design, Development, Scanning, Ticketing, Ticket Systems, Events, Event Ticketing, Minimum Viable Product (MVP), Web & Mobile Applications, Mobile App Development, Mobile UI, Mobile UX, Push Notifications, Mobile Applications, Startup Consulting, OpenAI, App UI, App UX, Full-stack Development, UI Development, Mobile/Web Project Management, API Design, Apps, App Design, Technical Leadership, App Store, Google Play Store, Leadership, Architecture, Firebase Cloud Functions, Figma to React, Web Scraping, AI Automation, Mobile Apps, AI Chatbots, Large Language Models (LLMs), API Integration, Live Chat, Artificial Intelligence (AI), Maps, Big Data, Location Services, Scraping, Genkit, Unique Business Ideas

Collaboration That Works

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