Andrej Gajdos
Verified Expert in Engineering
Full-stack Developer
Prague, Czech Republic
Toptal member since August 31, 2016
Andrej is a full-stack developer with a focus on the PERN/MERN stack and over 10 years of experience delivering software. As a fractional CTO and tech lead, Andrej has managed several teams delivering software for worldwide clients in many industries, including healthcare, finance, and eCommerce. Thus far, Andrej has delivered over 20 projects for startups, digital agencies, and Fortune 500 companies such as Apple and Binance.
Portfolio
Experience
- Front-end Development - 8 years
- Front-end Architecture - 8 years
- JavaScript - 8 years
- UI Development - 8 years
- Software Architecture - 6 years
- Node.js - 6 years
- React - 5 years
- Single-page Applications (SPAs) - 3 years
Availability
Preferred Environment
OS X, Visual Studio Code (VS Code)
The most amazing...
...thing I've developed is a pixel-perfect user interface for Apple.
Work Experience
Fractional CTO, Software Architect, Senior Full-stack Developer
Self-employed
- Consulted strategically with companies on the product development roadmap, developing workflow, setting project infrastructure, architecting and implementing third-party integrations, and providing code reviews.
- Mentored senior developers with best practices, design patterns, and tools to scale web applications in maintainability and performance.
- Refactored and improved codebases that saved customers at least six figures in future development.
- Developed an interactive data visualization that renders thousands of buildings on a map, and users can edit buildings by editing polygons.
Software Architect
GoSchoolBox
- Optimized the platform and scaled infrastructure to allow the users' growth from 50,000 to 1 million.
- Solved performance issues and user flows from 10-15 seconds to 1.5 seconds.
- Improved database search functionality to allow users to search across millions of records within 20 seconds.
Fractional CTO
Provenance
- Provided strategic consulting on a product development roadmap, setting engineering pacing to successfully finish an MVP.
- Set up infrastructure and CI pipelines, and conducted code reviews to identify issues before they translated into technical debt.
- Helped developers with best practices and leveraged tooling to speed up the development process and ensure code quality.
React and Gatsby Developer
Nash
- Built customizable UI components used across multiple projects. Built funds management and payment systems in the exchange platform.
- Worked on the Nash extension, a browser-based cryptocurrency wallet, and Chrome extension.
- Built the company website in React, Gatsby, and TypeScript.
React Developer
FastSwims
- Designed and built a functional prototype of an event management platform for organizing swimming teams and swimming competitions.
- Designed a new user interface based on the customer's prototypes.
- Built a functional prototype from scratch as a single-page application.
React Developer
Glofox
- Helped deliver a React Native project used for managing fitness studios.
- Fixed various bugs and issues in the React Native project.
- Optimized the React Native project for the Android platform.
Principal Software Engineer
Saycaster
- Worked as a full-stack JavaScript developer using React and Node.js.
- Designed and built an interactive podcast platform. Podcasters can upload audio files and add "spots" to specific moments in their podcasts, which can be anything from links to social media posts, videos, or images.
- Built a single-page app from scratch with a complex user interface, including user interactions and animations.
- Architected and built the project architecture and server.
Pre-sales Engineer
ZeroTurnaround
- Presented and demonstrated products to potential customers from all over the world.
- Demonstrated product features to developer teams and showed how to use them in the development process with a specific workflow, environment, and toolset.
- Helped sales associates close deals by presenting our products in specific use cases.
- Trained sales associates on how to effectively present and sell our tools to developer teams and managers.
- Assisted customers with installation, troubleshooting, and other customer services for configuration issues.
Software Engineer
Ataccama
- Worked mainly as a front-end developer on dashboards and data visualizations.
- Implemented new features and fixed bugs in enterprise applications used for data quality management and rewrote UI components to modern technologies.
- Designed and implemented the front end of an interactive application for customer data management.
- Designed and implemented the server-to-sever communication and a server push in the GWT application.
Data Visualization Developer
Techniserv, Taranzo
- Analyzed, designed, and implemented solutions for gathering and processing structured and unstructured data from social networks and various other sources.
- Designed and implemented a module for building and visualizing a social network.
- Built data processing from social networks, such as YouTube and Twitter.
Software Tester
Amberg Group
- Executed both manual and automated tests and analyzed the results.
- Developed and maintained the whole test infrastructure with automated tests.
- Designed test cases, wrote documentation, and reported issues.
Experience
Provenance
https://app.provenance.co/GoSchoolBox
https://goschoolbox.com/3icap
https://www.3imembers.com/I designed and implemented the integration with 3rd-party services, such as DocuSign, Slack, and Stripe. I also helped the team set up the project tooling, fix various issues, and implement new features.
Stackbit
https://app.stackbit.comI helped Stackbit's team set up the tooling and design the architecture for the design system of the main platform. I assisted and mentored senior React developers on best practices and patterns to solve complex flows in React projects. I fixed various issues and bugs in the platform and on additional feature sets for enterprise clients.
Getctrl
https://www.getctrl.co/I developed new features and fixed the existing codebase as a front-end developer. I also helped and mentored senior React developers on best practices.
Nash.io
https://nash.io/I built this company website from scratch, adding and reusing existing components from Storybook.
Cryptocurrency Exchange Platform
https://app.nash.io/Joined the project as a React developer and implemented a design system, portfolio management, and payment systems. I used React, TypeScript, Storybook, and GraphQL.
Archipelago
https://archipelago.art/Security Tokens Offering Platform
System Master Planner
I worked as a React developer and developed interactive data visualization, rendering thousands of buildings as polygons on a LeafletJS map.
FastSwims
https://www.fastswims.com/Development tools: JavaScript, React, and Redux-Saga.
Saycaster Rebranded to Bitcast
• Podcasters can upload their audio and add 5-20 spots to their podcasts.
• These spots can be anything from links to social media posts to other videos or images.
• Listeners can listen and comment on these specific spots.
SushiSwap Migrator
https://sushi-migrator.vercel.app/Vertigo
Potentials
Notion API Connector
https://notionapiconnector.com/CHROME WEB STORE LISTING https://chrome.google.com/webstore/detail/notion-api-connector/bafkcebllidammdngjlpcgnoodkappdg
SalesforceToNotion
https://salesforcetonotion.com/CHROME WEB STORE LISTING
https://chrome.google.com/webstore/detail/salesforcetonotion/dlebnfljbolfokomdlcdddgdopiaekeg
Filipi
Tauchain
Software Development Blog
https://andrejgajdos.com/blogIvana Neckarova
Link Preview Generator
https://www.npmjs.com/package/link-preview-generatorNeo Transfer
https://github.com/AndrejGajdos/neo-transferNewsfeed Cryptogoods
https://github.com/AndrejGajdos/newsfeed-cryptogoodsAuthenticating Users in SPA using Node.js, Passport.js, React, and Redux
https://github.com/AndrejGajdos/auth-flow-spa-node-reacthttps://andrejgajdos.com/authenticating-users-in-single-page-applications-using-node-passport-react-and-redux/
Development tools: JavaScript, Node.js, React, Redux, Passport.js.
Nested Datatables
https://andrejgajdos.github.io/nested-datatables/Development tools: JavaScript and jQuery.
Webpack Setup for ES6, React, Sass, and Bootstrap
https://github.com/AndrejGajdos/webpack-reacthttps://andrejgajdos.com/setting-up-webpack-for-es6-react-sass-and-bootstrap/
Development tools: JavaScript, React, and Webpack.
Social Graph
Development tools: Java, JavaScript, Liferay, JSP, Jung, OrientDB, D3.js, Bootstrap
Sample Source Code
Instructions:
• Install Node.js from nodejs.org/en/download/.
• Install Bower from bower.io/#install-bower.
• Go to the project root directory in the terminal and install other dependencies, i.e., npm install and Bower install.
• Follow npm run start.
• Open the URL localhost:8080/ and type in:
a) User: andrej
b) Password: nachos
SVG Sprite into PNG
https://github.com/AndrejGajdos/svg-sprite-to-pnghttps://andrejgajdos.com/how-to-convert-svg-sprite-into-png-images/
Development tools: JavaScript, Gulp
Server Push in GWT Application with Errai
https://github.com/AndrejGajdos/gwt-errai-messaginghttps://andrejgajdos.com/first-steps-with-gwt-and-errai-messaging/
Development tools: Java, GWT, Errai
Contract Generator Tool
Development tools: C#/.NET, WPF, SQLite, ADO.NET
Personal Calendar
https://github.com/AndrejGajdos/personal-calendarDevelopment tools: Java, JSP, Swing, SwingWorker, MySQL, JDBC
Education
Master's Degree in Service Science, Management, and Engineering
Masaryk University Brno - Brno
Erasmus Exchange Student in Master in Innovation and Research in Informatics
Polytechnic University of Catalonia - Barcelona
Bachelor's Degree in Applied Informatics
Masaryk University - Brno
Skills
Libraries/APIs
Underscore.js, React, Node.js, React Router, REST APIs, Atomic CSS, Passport.js, jQuery Plugins, jQuery UI, Redux-Saga, D3.js, Immutable.js, JSTL, Chai, jQuery, JavaScript Charting, AWS Amplify, GitHub API, X (formerly Twitter) API, YouTube API, Objection.js, JDBC, Backbone.js, OpenGL, Win32 API, Windows Forms (WinForms), Java Message Service (JMS), Leaflet, MobX, Web3.js, Stripe, Stripe API, Puppeteer, Slack API, Salesforce API
Tools
Git, Redux Thunk, Webpack, Gulp, Bower, Mocha, Emacs, PostCSS, Knex.js, Babel, GitLab, GitHub Pages, GitHub, Trello, InVision, ActiveMQ, Apache Maven, CircleCI, Figma, LaunchDarkly, Slack, Notion, Sentry, MongoDB Atlas, NPM
Languages
JavaScript 6, CSS, HTML, CSS3, HTML5, JavaScript, TypeScript, Object-oriented JavaScript (OOJS), Java, Less, SCSS, Sass, ECMAScript (ES6), SQL, GraphQL, C, Python, Ruby, PHP, C#, UML, C++
Frameworks
Express.js, Redux, Next.js, Koa, Bootstrap, Spring MVC, Flux, JUnit, Tailwind CSS, Material UI, Errai, React Native, Ruby on Rails (RoR), Jakarta Server Pages (JSP), Swing, Windows Presentation Foundation (WPF), .NET, Jest, Cypress, Selenium
Paradigms
Model View Controller (MVC), Unit Testing, Object-relational Mapping (ORM), Agile Software Development, Functional Programming, REST, Object-oriented Programming (OOP), Object-oriented Design (OOD), Software Testing, Automated Testing, Search Engine Optimization (SEO), Requirements Analysis, Web Architecture, Responsive Layout, Agile, Refactoring
Storage
JSON, PostgreSQL, Amazon S3 (AWS S3), Graph Databases, SQLite, MySQL, OrientDB, MongoDB, Relational Databases, Databases, Datadog, Cloud Firestore
Platforms
Firebase, Java EE, WordPress, Contentful, Amazon Lightsail, AWS Lambda, Amazon Web Services (AWS), OS X, Heroku, Amazon, MacOS, Windows, Linux, Blockchain, X (formerly Twitter), Amazon EC2, Web, Mapbox, Visual Studio Code (VS Code), Salesforce, Vercel
Other
Responsive UI, UI Development, Ajax, Front-end, Single-page Applications (SPAs), Web Development, Full-stack, Front-end Development, Front-end Architecture, Websites, Development, React Hooks, Web App Development, Minimum Viable Product (MVP), User Interface (UI), Atomic Design, Software Engineering, Web Applications, Interactive UI, Dashboards, UI Components, UI Libraries, Component Libraries, API Integration, APIs, Back-end, ESLint, Technical Consulting, Back-end Development, Writing & Editing, Data Visualization, Presentations, Sales, Customer Service, Consulting, Programming, Software Design, Styled-components, Gatsby, CTO, Architecture, Software Architecture, Full-stack Development, Solution Architecture, Slate, Responsive Design, Apollo, User Experience (UX), MERN Stack, Leadership, Startups, Cloudflare, Prismic, Webhooks, Storybook, JUNG, SVG, Web Scraping, Social Networks Development, Data Analysis, Liferay, BPM, Messaging Patterns, Sales Presentations, Chrome Extensions, Ethers.js, Scraping, Prototyping, Technical Leadership, IT Consulting, Tech Sales, CSS-in-JS, Technology Consulting, Team Leadership, Local SEO, API Design, eCommerce, Strapi, Solution Design, APM, Performance, Server-side Rendering (SSR), UI Testing, CI/CD Pipelines, Optimization, Crypto, Non-fungible Tokens (NFT), SaaS
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