Zsolt Bako, Developer in Weston-super-Mare, United Kingdom
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Zsolt Bako

Verified Expert  in Engineering

Full-stack Developer

Weston-super-Mare, United Kingdom
Toptal Member Since
December 4, 2015

Zsolt is a self-taught developer and entrepreneur. He is a born problem-solver who started coding when he was eight and learned to create in several vastly different environments. He gained solid experience in the JavaScript ecosystem and co-founded his niche social network startup. Zsolt's experience working in and leading remote teams and his eagerness to keep learning new technologies make him a valuable asset for any client who wants exceptional results.


The Think Tank Education LLC
React, Node.js, JavaScript, NestJS, MobX, Redis, MongoDB, Scaling, Optimization...
Stubhub - Engineering
React, TypeScript, JavaScript, Front-end, React Query, C#, C#.NET...
Scope Tickets
Next.js, JavaScript, Front-end Development, Front-end Design, Figma, Stripe...




Preferred Environment

Docker, Git, Visual Studio Code (VS Code), Linux, MacOS

The most amazing...

...challenge I've had was architecting an event-driven microservices platform for a gaming company and leading a diverse team to implement it to high standards

Work Experience

Node.js and React Developer

2022 - PRESENT
The Think Tank Education LLC
  • Planned, architected, and developed an educational app where students can solve math quizzes and see a detailed report of their progress during the year. It allows their teachers and school admins to see aggregated and individual statistics.
  • Coordinated with the client to determine and fine-tune the requirements for a great user experience.
  • Architected a full-stack web application from scratch, balancing the ability of rapid prototype development and future scalability.
  • Coordinated the production launch of the application, measured various performance metrics, ran customized benchmarks to estimate the solution's scalability, and then continuously improved the app to allow the smooth calculation of millions of results.
  • Created a data pipeline for continuously calculating dozens of aggregated analytics based on individual student results to provide excellent visibility for teachers, school administrators, and internal monitoring.
  • Designed the app's UI in line with the requirements of the clients and different kinds of users. Created reusable front-end components to achieve the desired goals and make a great user experience.
  • Integrated a LaTeX presentational component to display math quiz problems and answers to accurately and beautifully present scientific and math formulas.
  • Created a dynamic quiz generator that opens up the possibility of customized learning experiences.
Technologies: React, Node.js, JavaScript, NestJS, MobX, Redis, MongoDB, Scaling, Optimization, Architecture, Full-stack, Tailwind CSS, Responsive UI, Front-end, Chart.js, LaTeX, Design, Software Architecture, Software Engineering, E2E Testing, Playwright, Data Visualization, Webpack, Redux Toolkit, API Integration, Unit Testing, Scalability, CircleCI, Bash Script, Moment.js, Lodash, NoSQL, Agile Software Development

Senior Front-end Developer

2024 - 2024
Stubhub - Engineering
  • Strengthened the team with rapid development at a critical phase to achieve a timely and high quality MVP release.
  • Rewrote the Column Formula Builder using a custom built tokenized formula editor to provide a flexible tool for the users with great UX.
  • Set up E2E tests using Playwright to improve the app's reliability and discover bugs before releases.
  • Developed new features and improvements and fixed bugs in the client's PoS app following the stakeholders' quickly changing requirements.
Technologies: React, TypeScript, JavaScript, Front-end, React Query, C#, C#.NET, Vanilla Extract CSS, Playwright, E2E Testing, Unit Testing, Lodash, Agile Software Development

Senior Front-end Developer

2022 - 2024
Scope Tickets
  • Took over the front-end development of an event ticketing system for university events.
  • Refactored parts of the business logic to match the back end closely and eliminate bugs.
  • Improved the integration with Stripe Payment Elements and an internal ticket escrow system.
  • Enhanced the themed UI to be consistent with the design.
  • Made changes to the design of the UI components to improve readability and achieve a sleek and modern user interface.
  • Implemented ticketing for event series, timed tickets, and multi-day tickets.
Technologies: Next.js, JavaScript, Front-end Development, Front-end Design, Figma, Stripe, Webpack, Redux, React, C#, C#.NET, React Query, Lodash, Agile Software Development

Back-end Team Lead & Architect

2022 - 2023
Fabzen Technologies
  • Led a continuously growing back-end development team of a real money gaming company.
  • Crafted the microservices architecture of a multi-game single platform back end that serves millions of players.
  • Designed and created a vastly scalable event bus built on top of AWS SQS, which had AMQP and Kafka-like capabilities with a more straightforward interface and lower maintenance needs.
  • Translated the continuously changing business requirements into actionable development stories.
  • Developed a scheduler-based real-time gaming engine suitable for card games and board games using Socket.IO.
  • Coordinated the integration with the mobile app by discussing and specifying the internal REST APIs and Socket.IO interface.
Technologies: Node.js, Gaming, Socket.IO, RabbitMQ, Microservices, Concurrent Programming, TypeScript, Amazon Simple Queue Service (SQS), Amazon Web Services (AWS), Amazon S3 (AWS S3), Amazon Elastic Container Service (Amazon ECS), Docker, NestJS, Jest, Message Bus, Realtime, Message Queues, AsyncAPI, OpenAPI, Software Architecture, Back-end, REST APIs, Software Engineering, Team Management, Team Mentoring, Technical Hiring, Cross-functional Collaboration, Jira, Scrum, Amazon ElastiCache, Amazon Cognito, Technical Leadership, JavaScript, API Integration, Scalability, CircleCI, Lodash, Architecture, Amazon EC2, Agile Software Development

Senior Full-stack Developer

2022 - 2022
Fly & Fetch
  • Contributed to the rewrite of the Svelte-based front end.
  • Implemented new features across the full stack.
  • Stabilized the platform by rewriting error-prone parts of the codebase and adding an automated end-to-end testing suite using Playwright.
  • Fixed security vulnerabilities to ensure the platform's integrity and data safety.
  • Improved the developer experience and efficiency in the team by switching to better tooling and services.
Technologies: JavaScript, FeathersJS, MongoDB, MongoDB Atlas, Svelte, Amazon S3 (AWS S3), APIs, REST, Stripe API, Stripe, Web Development, CSS, Amazon Web Services (AWS), REST APIs, GitHub, HTML, Full-stack, Full-stack Development, Responsive UI, Tailwind CSS, E2E Testing, Node.js, CircleCI, Moment.js, Lodash, Architecture, Facebook API, Amazon EC2, NoSQL, Agile Software Development

Senior Full-stack Developer

2020 - 2022
Argo Group
  • Reimplemented an internal document store and a search platform from scratch as a sole developer.
  • Architected and built a Node.js back end using Elasticsearch as a central document metadata storage and search engine.
  • Created a React-based front end that provided an instant search functionality to the users.
  • Implemented complex filtering, verification, and exporting capabilities.
  • Maintained various other legacy applications.
Technologies: AWS Lambda, Amazon S3 (AWS S3), Amazon API Gateway, AWS IAM, Node.js, Express.js, React, Elasticsearch, Web Development, CSS, SQL, Amazon Web Services (AWS), REST APIs, GitHub, Amazon RDS, PostgreSQL, HTML, Full-stack, MySQL, Full-stack Development, Responsive UI, Concurrent Programming, Serverless Architecture, Lambda Functions, Amazon Cognito User Pools, Amazon Cognito, Okta, JavaScript, API Integration, Serverless, Lodash, Agile Software Development

Senior Front-end Engineer

2018 - 2020
Patron Technology
  • Developed a powerful event marketing analytics platform as part of a small team.
  • Focused primarily on implementing new features on the front end, such as advanced filtering, visualization components, and user management.
  • Extended the internal API back end to provide the necessary data efficiently from the Elasticsearch data warehouse and MySQL.
  • Implemented React components using D3.js to visualize data on the analytics dashboard.
  • Created and improved reusable visualization components using Storybook.
Technologies: Elasticsearch, MySQL, Node.js, D3.js, Redux, TypeScript, React, Web Development, CSS, SQL, Amazon Web Services (AWS), REST APIs, GitHub, Amazon RDS, PostgreSQL, HTML, Dashboards, Data Analytics, Responsive UI, Storybook, Data Visualization, Webpack, JavaScript, Lodash, Agile Software Development

Senior Full-stack Developer

2016 - 2018
  • Led the building of a Kanban-like applicant tracking system using TypeScript, React, MobX, and Firebase.
  • Rebuilt the legacy web app for job seekers using TypeScript, React, MobX, and Video.js. Applicants could record videos using the app.
  • Contributed to the core rewrite to handle different user journeys well using the state machine approach.
Technologies: MongoDB, GraphQL, Firebase, MobX, React, TypeScript, AWS Lambda, Node.js, Express.js, Web Development, CSS, Amazon Web Services (AWS), REST APIs, GitHub, HTML, Full-stack, Full-stack Development, Responsive UI, JavaScript, API Integration, CircleCI, Amazon EC2, Agile Software Development

Back-end Developer

2015 - 2016
  • Developed a scheduled digester that processes third-party data to an in-house database.
  • Extended the REST API of the game.
  • Refactored legacy codes into maintainable software.
  • Developed new functionalities for the existing back end.
  • Integrated PayPal payment solutions.
Technologies: Kue, MongoDB, Express.js, Node.js, Web Development, REST APIs, Gaming, JavaScript

Lead Developer and Co-founder

2013 - 2015
  • Prototyped the MVP rapidly using Meteor.
  • Architected the final product with the help of a senior adviser.
  • Developed microservices for a social network.
  • Planned and implemented RabbitMQ-based communication between microservices.
  • Created a custom algorithm to determine a neighborhood of users.
  • Set up a scalable infrastructure for the growing social network.
  • Led a small team of talented developers.
Technologies: React, Redis, RabbitMQ, Restify, Express.js, Node.js, Web Development, CSS, REST APIs, Hapi.js, HTML, Full-stack, Full-stack Development, Azure, Sockets, Responsive UI, Socket.IO, Concurrent Programming, JavaScript, API Integration, AMQP, Architecture, Facebook API, CoffeeScript, Google API, NoSQL, Agile Software Development

Mosaic Puzzle

Mosaic Puzzle is a simple game that I created using Fabric to learn the cornerstones of the library. It puts rectangular pieces of an image randomly on the canvas, and using drag and drop, the user can stick them together by the automatic grouping of objects.


A multiplatform, truly serverless secure personal finance app being developed using the Flutter framework. The app will be capable of handling everyday finances (income/expense/assets/liabilities tracking) extended with an opinionated budget handling and solid investment tracking/planning features. The project's goal is to enable users to take control of their personal financial freedom.


As a lead developer, I mainly contributed to the back end of the application, and I also developed some parts of the front end. The Node.js back end is based on a microservices architecture and provides advanced solutions for calculating a dynamic neighborhood boundary for users, generating relevant news feed, showing targeted advertisements, and more.

MongoDB Promisified Connector

A Node.js MongoDB connector, promisified with Bluebird.

It is lightweight and efficient, offering all the functionality of the native MongoDB driver and initiating a single connection the first time a user tries to access a collection (lazy loading). It is also fault-tolerant; it tries to reconnect if disconnected. Other features include custom logging and a Harmony proxy: the user must run Node.js with a "–harmony_proxies" argument.

Calorie Counter App

A simple app built for learning new technologies like AngularJS 2.0, TypeScript, and custom simplified Flux architecture.

The app provides an interface to enter and track your calories and edit and delete your data. It also contains two different administrative roles to manage the data of all users.
2005 - 2008

Professional Degree in Software Designer Mathematics

Eötvös Loránd University - Budapest


React, Node.js, MobX, REST APIs, D3.js, Lodash, Moment.js, Restify, AMQP, Stripe, Socket.IO, Chart.js, React Query, Google API, PayPal API, Facebook API, Stripe API, Sockets, Fabric, OpenAPI, Playwright, Vanilla Extract CSS


GitHub, Gulp, Jira, Bamboo, Git, RabbitMQ, Kue, CircleCI, Redux Toolkit, Babel, Docker Swarm, AWS IAM, MongoDB Atlas, Canvas, Canvas 2D, Figma, LaTeX, Amazon Simple Queue Service (SQS), Amazon Elastic Container Service (Amazon ECS), Amazon ElastiCache, Amazon Cognito, Webpack


Express.js, Koa, Redux, Flutter, Tailwind CSS, Hapi.js, Angular, FeathersJS, Svelte, AngularJS, NestJS, Next.js, Jest, Realtime


TypeScript, JavaScript, CSS, HTML, PHP, SQL, Bash Script, Dart, GraphQL, CoffeeScript, Python, C#, C#.NET


Promise, REST, Agile Software Development, Microservices, Unit Testing, Concurrent Programming, E2E Testing, Serverless Architecture, Functional Reactive Programming, Scrum


Linux, Docker, Heroku, Amazon Web Services (AWS), Amazon EC2, AWS Lambda, Firebase, MacOS, Azure


MongoDB, Amazon S3 (AWS S3), Redis, NoSQL, MySQL, Elasticsearch, PostgreSQL


APIs, Full-stack, Web Development, Full-stack Development, Responsive UI, Front-end, Back-end, API Integration, Scalability, Caching, Cloud, Architecture, Amazon RDS, Dashboards, Data Analytics, Optimization, Data Visualization, Serverless, Lambda Functions, Chrome Extensions, Web Components, Amazon API Gateway, Gaming, Scaling, Storybook, Front-end Development, Front-end Design, Design, Software Architecture, Software Engineering, Message Bus, Message Queues, AsyncAPI, Team Management, Team Mentoring, Technical Hiring, Cross-functional Collaboration, Bluebird, Amazon Cognito User Pools, Okta, Technical Leadership

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