Tomislav Krnic, Developer in Ghent, Belgium
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Tomislav Krnic

Verified Expert  in Engineering

Full-stack Developer

Location
Ghent, Belgium
Toptal Member Since
October 12, 2012

Tomislav is a full-stack developer and designer with over 20 years of experience. He has recently focused on React Native mobile development and real-time databases. He has founded or co-founded six businesses with three successful exits. He prides himself on a proven record of building full solutions with tangible results.

Portfolio

CityX Apps
Firebase, React Native, iOS, Android, React, APIs, Card Payments, Payment APIs...
Yahn Enterprises, LLC
React Native, Firebase, iOS, Android, Mobile UI, Mobile UX, Startup Consulting...
Entrio
React Native, UI Design, UX Design, Firebase, Firebase Realtime Database, APIs...

Experience

Availability

Part-time

Preferred Environment

React Native, Firebase, User Interface (UI), Startups, Unique Business Ideas, CSS, Full-stack, UI Design

The most amazing...

...ability I have is that I can turn a basic business idea into a functional and understandable project that users know how to use.

Work Experience

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

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

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

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

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

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

Senior Front-end Developer

2014 - 2014
LogoGarden
  • Designed and developed the company website and improved the UI/UX for responsive websites.
  • Utilized technologies, including HTML, CSS, jQuery, JavaScript, and Sass, for the project.
  • Built LogoGarden, an online logo creation for your business with over 2.5 million custom logos made. Users can create their logos fast and for free.
Technologies: HTML5, Sass, CSS, jQuery, JavaScript, User Interface (UI), User Experience (UX), Full-stack, UI Design, Front-end Development, Full-stack Development

Senior Front-end Developer

2013 - 2013
Rock Lobby (via Toptal)
  • Developed a custom CMS solution.
  • Developed UI/UX elements using jQuery.
Technologies: MySQL, PHP, CSS, jQuery, JavaScript, HTML5, User Interface (UI), User Experience (UX), Full-stack, UI Design, Front-end Development, Full-stack Development

Front-end Developer

2012 - 2013
Rise Events (via Toptal)
  • Developed four websites for this Washington D.C.-based real estate company.
  • Designed four connected web pages based on the same style with small variations.
  • Created a jQuery/GoogleMap system to display location on mouseover.
Technologies: Google Maps API, JavaScript, jQuery, CSS3, HTML5, Web Design, User Interface (UI), User Experience (UX), Full-stack, UI Design, Front-end Development, Full-stack Development

Front-end Developer

2012 - 2013
Eminent Domains/IMissYou (via Toptal)
  • Created a strong and user friendly front-end with many jQuery features.
  • Built a beautiful but technically complex layout with a combination of photos/videos/Twitter/Facebook/message and models put in masonry composition.
Technologies: JavaScript, jQuery, CSS3, HTML5, User Interface (UI), User Experience (UX), Full-stack, UI Design, Front-end Development, Full-stack Development

Senior Web Developer

2012 - 2012
Design Theorem/oMiami (via Toptal)
  • Handled project finalization to solve problems with connecting scrolling events and pointing places on maps.
  • Took care of various advanced CSS tasks.
Technologies: jQuery, HTML5, CSS3, User Interface (UI), User Experience (UX), Full-stack, UI Design, Front-end Development, Full-stack Development

Owner, Senior Web Developer (Code and Design)

2001 - 2012
Studio Cro-Design
  • Created a photo community site independently with over 13,000 users in the Croatian photography community. Received numerous recognitions and included over 800 themed competitions. Looked into expanding the site to the US market.
  • Created a B2B image sharing system for Mars, a large food distribution company. Designed initially for Mars Croatia, but later expanded to Mars Europe. Included automated image preparation, zip file creation, and download management.
  • Developed a CMS for a real estate agency, including multi-language support and a best property search features.
  • Wrote a fully automated system that used Expedia API for booking hotels and flights.
  • Created a small corporate web page with a clean design displaying a simple, custom CMS and moderate use of jQuery and Flash.
Technologies: CSS3, HTML5, Ajax, jQuery, MySQL, PHP, User Interface (UI), User Experience (UX), Full-stack, UI Design, REST APIs, Full-stack Development

Co-founder, Web Project Manager, Senior Developer

2009 - 2011
iKiosk
  • Developed a system independently for formatting and selling digital magazines, books, and newspapers. Won recognition from Forbes magazine as a great internet business project.
Technologies: CSS, Ajax, jQuery, CSS3, HTML5, MySQL, PHP, User Interface (UI), User Experience (UX), Full-stack, UI Design, Front-end Development, REST APIs, Full-stack Development

Touchmoon Messenger

This is a mobile messenger of the new generation.

I acted as a co-founder for this project, developing front- and back-end services, app games, and many other features that I created over 3+ years of hard work.

Grga - Mobile Ordering and Payment App

A mobile payment app available in many cafes in Croatia.

I acted as the co-founder and full-stack mobile developer for a mobile payment app available in many cafes in Croatia. The application is in the top 10 of the App Store, with over 100 stores and 9,000 users.

TECHNOLOGIES AND APPLICATION CHARACTERISTICS:
• React Native
• Redux
• API
• Cash register connection
• Payment system (accepting all major credit cards)
• QR reader
• Firebase authentication, messages, analytics, function/back-end
• Notifications
• API Connect
• UI/UX
• App Store and Google Play

Apps.apple.com/hr/app/grga-tvoj-digitalni-konobar/id1439087229?l=hr
Play.google.com/store/apps/details?id=com.grga&hl=e

Undiet Tracker

An app, built in React Native, for weight loss motivation and tracking. I came up with the idea for the app, handled coding, and designed the UI/UX.

• React Native
• Redux
• Firebase DB/storage, authentication, messages, analytics, function/back end
• Notifications
• UI/UX
• App Store and Google Play
• Landing page

Development time: 25 days

The app is available at:
• https://apps.apple.com/us/app/undiet-tracker/id1490849895?ls=1
• https://play.google.com/store/apps/details?id=com.undiet&hl=en

AirQuality and Weather Chat

https://apps.apple.com/us/app/airquality-and-weather-chat/id1495791987?ls=1
• Air Quality cover more than 11,000 world stations in more than 1000 cities. Live data covers all relevant air quality information for all pollutants.
• Live weather data, 200,000 cities
• Chat, based on the nearest measuring station

• React Native
• Redux
• Firebase authentication, messages, analytics, function/back end
• Notifications
• API connect
• UI/UX
• App Store and Google Play
• Landing page

Development time: 20 days

Fishing Pro App

https://fishingpro.cityx.hr
I was actively involved in developing the Fishing Pro app, a comprehensive tool designed for fishing enthusiasts and casual anglers. The app features a solunar-based calendar predicting optimal fishing times and a sophisticated tracker for logging fishing activities. Users can share their experiences with the community, enhancing social engagement.

A notable innovation is the AI-enabled fish recognition tool, which provides details like size, weight, and catch difficulty. My role extended to integrating in-app purchases and subscriptions, leveraging 3rd-party services for improved sales efficacy, and overseeing the app's UI/UX design to ensure a user-friendly experience. Using Redux and Firebase, the app was developed as a robust MVP, blending technology with the outdoor fishing adventure.
2001 - 2005

Bachelor's Degree in IT Engineering

Polytechnic University of Zagreb - Zagreb, Croatia

Libraries/APIs

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

Tools

Adobe Photoshop, ChatGPT, Adobe Illustrator, Figma

Frameworks

React Native, Redux, Smarty

Languages

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

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)

Industry Expertise

Web Design

Storage

JSON, MySQL, Firebase Realtime Database, 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, Live Chat, Artificial Intelligence (AI), Maps, Unique Business Ideas

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