Martina Zrnec, Developer in Zagreb, Croatia
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Martina Zrnec

Verified Expert  in Engineering

Web Developer

Zagreb, Croatia
Toptal Member Since
December 8, 2019

Martina is motivated and eager to learn more daily and contribute anywhere needed. She gained experience working in a fast-paced, multicultural startup where coding new features and deployments were done weekly. She is a full-stack developer focused on JavaScript technologies and the MERN stack. She has a strong focus on getting things done and understanding a business, and she is moved by the actions taken by individuals every day. Martina ensures the focus is on tangible results.


IMO Interns
Agile, Agile Software Development, TypeScript, React, GraphQL, CTO...
Exemplar Human Services, LLC (via Toptal)
React, HTML, CSS, JavaScript, React Query, Jira, REST, REST APIs, Agile, Axios...
Agile Software Development, React, Node.js, Jira, Trello, Stripe, Stripe API...




Preferred Environment

Visual Studio Code (VS Code), Git, React, Node.js, PWA, Figma, Scrum, MacOS, JavaScript, Team Leadership

The most amazing...

...thing I've improved company-wise is removing content adding from the engineering team to a headless CMS by connecting to our internal CD processes (deployBot).

Work Experience

Fractional CTO

2024 - PRESENT
IMO Interns
  • Broke down the decision to develop an in-house time management app or integrate it with the existing solution.
  • Created a pro/cons list with a couple of options for the cost/benefits of implementing on our own. After this, the decision was easy to go with an existing solution.
  • Moved the team from not being led to focused, sprint-orientated development with small, incremental tasks to boost the morale of getting stuff done.
  • Implemented the automatization for inviting clients to the application and sending them emails from manual work to usage of our admin platform. Utilized Signaturely and Encharge for capturing webhooks and sending emails.
  • Oversaw the development of the integration time management app and ensured the code was up to the latest standards.
Technologies: Agile, Agile Software Development, TypeScript, React, GraphQL, CTO, Team Leadership, NestJS

Front-end Lead

2023 - PRESENT
Exemplar Human Services, LLC (via Toptal)
  • Defined the front-end architecture, as well as which libraries to use and why—with appropriate documentation.
  • Developed the entire application based on Figma designs, creating distinctive paths and roles. Implemented React Router with secure private routes for both worker and client usage.
  • Used React Query with Axios for fetching the data and storing context.
  • Implemented i18n library for localization, added language switcher, and implemented the entire website in two languages.
  • Created 122 tests using Jest, React Testing Library, and MSW to ensure fewer bugs and seamless website usage.
Technologies: React, HTML, CSS, JavaScript, React Query, Jira, REST, REST APIs, Agile, Axios, Sass, Agile Software Development, ESLint, TypeScript, Jest, React Router, i18n, Localization, Yup, MSW, User Experience (UX), User Interface (UI)

Full-stack Web Developer

2019 - PRESENT
  • Developed the entire front-end UI components from Figma designs into React. Added PWA experience.
  • Brainstormed with clients about development paths, what to build and what not to build, proof of concept, scaling, and making robust applications.
  • Constructed the web architecture with leadership divided over two employees.
  • Integrated Stripe API with trial periods, monthly and yearly subscriptions, and withdrawals.
  • Utilized Node.js with Express.js on the back end, with session cookies and JWT tokens, expiring tokens, and refreshing and storing new ones.
  • Deployed React for the front end using Heroku and Node.js for the back-end applications with add-ons to track servers' performance, send emails, and use the DB. Used Atlas DB with different clusters for staging and production environments.
  • Incorporated ESLint and Prettier to make the codebase readable among developers and future coders. Used Git for the version control system for Toptal projects.
Technologies: Agile Software Development, React, Node.js, Jira, Trello, Stripe, Stripe API, Bootstrap, Styled-components, Axios, JSON Web Tokens (JWT), Heroku, CI/CD Pipelines, MongoDB, Express.js, Git, React Redux, Front-end, MERN Stack, Full-stack, HTML5, REST APIs, CSS, Visual Studio Code (VS Code), Redux, APIs, MacOS, Moment.js, Mongoose, Leadership, PWA, Figma, Progressive Web Applications (PWA), Scrum, TypeScript, Team Leadership, Web Architecture, Responsive UI, Software Architecture, Google Ads API, JavaScript, CSS3, HTML, User Experience (UX), User Interface (UI)

Front-end Developer

2023 - 2023
Celebrate Company GmbH
  • Developed admin application for complaints of specific products. It was a CRUD application to add, edit, update, and delete complaints.
  • Added front-end tests covering all functionalities created.
  • Contributed in two weeks sprint cycle with planning and tracking progress.
Technologies: TypeScript, JavaScript, React, Jest, Webpack, Tailwind CSS, CSS, CSS3, Git, Agile Software Development, React Redux, Front-end, MERN Stack, HTML5, HTML, Testing, Figma

Engineering Manager

2022 - 2022
  • Supported marketing and growth team efforts directly by making a clear path for analytics to be centralized in one place. Gave them more independence by making use of GTM and putting everything there.
  • Improved internal systems as a front-end lead by creating CI/CD pipeline, making content creators independent from developers. Content entered in Contentful triggered the DeployBot pipeline and updated the theme in Shopify.
  • Helped in creating the company's culture as the engineering manager. Embraced Agile methods after the constant firefighting mode the team was in.
  • Led the team to adapt to the complete localization of content.
Technologies: JavaScript, Angular, React, CSS, HTML5, Next.js, Contentful, Jira, Storybook, DeployBot, Shopify, Liquid,, Analytics, Figma, Localization, Klaviyo, SendGrid, AngularJS, APIs, REST APIs, Team Leadership, Remote Team Leadership, Responsive UI, Architecture, Software Architecture, Engineering Management, Hiring, Key Performance Indicators (KPIs), CSS3, Git, Front-end, MERN Stack, Redux, HTML, Leadership, eCommerce, User Interface (UI)

Web Developer

2019 - 2020
CIAL Dun & Bradstreet
  • Developed an entire admin platform to support our sales team in local countries.
  • Built a library of common functionalities and components to be reused on multiple in-house projects.
  • Worked mainly as a full-stack JavaScript engineer.
  • Created and maintained redux forms throughout the platform.
  • Checked and fixed the overall functionality of the application.
Technologies: Agile Software Development, Git, MongoDB, JavaScript, Node.js, Redux Form, React Redux, Redux, React, Front-end, MERN Stack, Full-stack, HTML5, REST APIs, Express.js, Bootstrap 3, CSS, CSS3, Docker, APIs, HTML, REST, MacOS, Moment.js, Bugsnag, Mongoose, Lodash, Testing, Scrum, TypeScript, Jira, Web Architecture, Visual Studio Code (VS Code), Responsive UI

Web Developer | Team Lead

2016 - 2019
  • Built a video player management system that combined sources from third-party player APIs like YouTube, Vimeo, Twitch, Brightcove, JW Player, Facebook, and HTML5 native player.
  • Developed a Chrome extension for the YouTube website, using our video player management system to enable all features directly while watching videos.
  • Made deployment process automated by creating an CI/CD system via Jenkins.
  • Built a DevOps environment on AWS, Elastic Beanstalk, load balancers, and security groups.
  • Composed a script to insert on-page that has videos to cut the best parts of it.
  • Supported and maintained our video player management system while desktop, mobile browsers, and video player APIs were altered and/or updated.
  • Extended the capabilities of the video player management system by adding a feature of sorting highlighted elements in any way and adding multiple video sources to cut the best parts.
  • Mentored junior and mid-level team members and onboarded new developers.
Technologies: Chrome Extensions, Amazon Web Services (AWS), Agile Software Development, Jenkins, Elasticsearch, MongoDB, Node.js, AngularJS, React, Front-end, MERN Stack, Full-stack, HTML5, REST APIs, WebStorm, Angular, Express.js, Bootstrap 3, CSS, Redis, APIs, HTML, REST, MacOS, Moment.js, Passport.js, AWS Elastic Beanstalk, Load Balancers, Mongoose, Lodash, Redux Thunk, Webhooks, Leadership, Testing, Scrum, Jira, Team Leadership, Web Architecture, JavaScript, Git, Visual Studio Code (VS Code), Bootstrap, Axios, Responsive UI, Architecture, Software Architecture, Analytics, CSS3, React Redux, Redux

Web Developer

2015 - 2016
  • Integrated a payment flow connecting to Stripe API.
  • Sent emails for users regarding new events and notifications using Mailchimp.
  • Developed a back-end validation for users to have different roles and views.
  • Created a map where users could see locations of every event happening nearby.
  • Developed an admin panel for internal use, managing user-profiles and adding, modifying, deleting, and granting event permissions.
Technologies: Git, Stripe, MongoDB, jQuery, JavaScript, Node.js, AngularJS, Front-end, Full-stack, Stripe API, REST APIs, WebStorm, Angular, Express.js, CSS, APIs, HTML, REST, MacOS, Passport.js, Mongoose, Webhooks, Trello, Web Architecture, HTML5, Responsive UI, Architecture, CSS3

Software Developer Intern

2014 - 2015
Hypo Alpe Adria Bank
  • Implemented SQL procedures to modify and save data.
  • Created the user-interface layout using WPF and following banking design patterns.
  • Learned about software development, working in a team, expressing new ideas, and asking for help when needed.
Technologies: MySQL, SQL, Windows Presentation Foundation (WPF), HTML, CSS, CSS3, HTML5

Women in Tech Hackathon

A three-day event for a women-in-tech hackathon held at headquarters in Amsterdam.

The competition was to present a clickable prototype in less than 48 hours. There were five teams of five people: a product manager, a front-end developer, two back-end developers, and a designer. In this competition, I was a front-end developer, and my main task was to connect with the back-end, extract data, and ensure that the feel and look of the page met all of the designer's ideas.

In the end, we achieved second place with the idea of a type of Santa Claus, i.e., Booking Claus, who gave the gift of travel.

Vibby is the easiest, online and free way to create a highlight reel from any video. Just paste a link on one or multiple videos, highlight the parts you want to show, reorder them in any way and share created Vibby on just about any social platform of your choice.


Magnises was a card-based membership club. The so-called black card, connected to an existing credit card for a monthly or yearly subscription, allowed user-exclusive perks. Benefits offered to members included VIP access to clubs, hotel discounts, and various exclusive events.

Kencko is a smart food company reinventing organic fruit and vegetable products to help people eat healthier and waste less.

Kencko’s smoothies come in a rainbow of flavors to suit your unique nutritional needs. Plus, all members can access free coaching from a registered dietitian to support them in growing their healthy habits with Kencko.

Getting more and more people to their daily servings of organic fruits and veggies through the beautifully crafted digital web shop, membership experiences, and platforms and tools built for scale.

A web application turned into PWA for the best mobile experiences to get introduced to people you want to meet. Introductions can be requested for personal, business, or academic reasons. Or become an introducer and get paid to introduce people in your personal, professional, and academic networks.

YouTube Video Tracking Tool
The most powerful YouTube ads spy tool on the market. A full-stack application in collaboration with Chrome extensions. While watching YouTube videos, when an ad appears, it could be added to your tracking collection in the application, where you could see all relevant analytics for that ad and compare it to others. It makes it simple to quickly find the funnels and ads crushing them in the specified niches so that you can model them yourself.
2013 - 2015

Master's Degree in Informatics and Telecommunications

University of Zagreb, Faculty of Electrical Engineering and Computing - Zagreb, Croatia

2010 - 2013

Bachelor's Degree in Informatics and Telecommunications

University of Zagreb, Faculty of Electrical Engineering and Computing - Zagreb, Croatia


Foundations of Project Management



React, Stripe API, REST APIs, React Redux, Redux Form, Stripe, Moment.js, Passport.js, Node.js, Lodash, jQuery, Liquid,, Google Ads API, React Query, React Router, Yup


Jenkins, WebStorm, Git, Bugsnag, Jira, Trello, Figma, Redux Thunk, Mongoose, SendGrid, Webpack


CSS, HTML, HTML5, CSS3, JavaScript, SQL, TypeScript, Sass, GraphQL


Angular, AngularJS, Express.js, Redux, Windows Presentation Foundation (WPF), Bootstrap 3, Bootstrap, JSON Web Tokens (JWT), Next.js, Jest, Tailwind CSS, NestJS


REST, Agile Software Development, Scrum, Testing, Web Architecture, Agile


MacOS, Amazon Web Services (AWS), Docker, Visual Studio Code (VS Code), AWS Elastic Beanstalk, Heroku, Contentful, Shopify, Klaviyo


MongoDB, Redis, MySQL, Elasticsearch


Chrome Extensions, APIs, MERN Stack, Front-end, Leadership, Full-stack, Team Leadership, Responsive UI, Architecture, Software Architecture, User Experience (UX), User Interface (UI), Webhooks, PWA, Progressive Web Applications (PWA), Load Balancers, Styled-components, Axios, CI/CD Pipelines, IT Project Management, Storybook, DeployBot, Analytics, Localization, Remote Team Leadership, Engineering Management, Hiring, Key Performance Indicators (KPIs), i18n, ESLint, MSW, CTO, eCommerce

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