Full-stack Developer in Prague, Czech Republic

Helped the team as a fractional CTO with strategic consulting on the product development roadmap. Managed and led a team of developers. I identified issues via code reviews before they were translated into technical debt, helped developers with best practices, and leveraged tooling to speed up the development process and ensure code quality. I also architected and built the project's infrastructure, CI pipeline, and third-party integrations.

GoSchoolBox is a SaaS platform that serves as the technical infrastructure layer between school districts and tutoring companies. The number of users grew from 50k to 1M. The GoSchoolBox platform has suffered from a significant number of application stability issues such as spontaneous error messages, gateway timeout errors, slow page load times and slow user flows.

My role as a software architect was to ensure platform stability, resiliency, and scalability. I helped the team to integrate and set up APM with metrics and performance dashboards to detect and diagnose end-user’s experience with mission-critical services. I refactored and fixed critical user flows to improve user flow performance, server throughput, and page load performance. I optimized Mongo search performance to allow users to search millions of records within seconds.

An investment community platform for investors to discover deals and identify co-investors. The platform allows investors to interact with each other, keep track of deals, and create a virtual investment club for a curated group of private investors.

I designed and implemented the integration with third-party services, such as DocuSign, Slack, and Stripe. I helped the team set up the project tooling, fix various issues, and implement new features.

Stackbit is a website builder that helps developers of any level build their Jamstack sites based on Next.js and Tailwind fast.

I 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 is a customer data platform for customer success professionals. It empowers post-sales people to bring data together from different apps to create their workspaces.

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.

A blazing-fast static website built with React, Gatsby, TypeScript, and styled-components. All pages are fully responsive and optimized for mobile viewing.

I built this company website from scratch, adding and reusing existing components from Storybook.

A cryptocurrency exchange platform.

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 is a next-generation NFT marketplace that offers curated generative art NFTs. As a front-end consultant, I helped the team review the existing codebase, refactor problematic flows, and fix various bugs and issues.

A secure, customer-centric, decentralized online securities exchange marketplace allows investors at all levels to buy and sell digital securities. The customer is a leading cryptocurrency exchange. I worked as a senior front-end engineer. I operated as an architect for front-end implementation and reviewed and audited the code of other front-end developers.

A computational tool for master planners, energy and resource managers, and policymakers. It allows users to evaluate sustainability and resiliency scenarios for large buildings and other assets.

I worked as a React developer and developed interactive data visualization, rendering thousands of buildings as polygons on a LeafletJS map.

An event management platform for managing swimming teams and swimming competitions. I designed a new user interface based on customers' prototypes and built a functional prototype.

Development tools: JavaScript, React, and Redux-Saga.

An interactive podcast platform with the following features:
• 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.

A web3.js project where users can migrate LP positions from Uniswap to SushiSwap. Users can interact with the Ethereum blockchain through MetaMask, view the ERC-20 tokens list and their LP positions, and add new ERC-20 tokens.

A project for a company in the marine industry. I worked as a data visualization specialist to build an interactive visualization of a Neo4j graph database. I developed this visualization in React, D3.js, and Storybook.

I built the user interface for this eCommerce tool in React. It helped the CEO and sales associates to maintain and process details about potential customers. I built the user interface using React and Tailwind.

Filipi is a furniture eCommerce store built with Next.js, Node.js, and MySQL. I helped the owner migrate the whole solution to another server, fix various issues and bugs in SEO, manage data, and set up analytics tools.

Created a Node.js back-end service that processes data from third-party APIs like third-party exchanges, GitHub API, Twitter API, and Telegram API. The server is deployed on AWS. I helped the client fix the project after previous developers and replaced the headless CMS solution.

My freelance software development blog. It was built with WordPress and JavaScript. I blog about tips, tutorials, and technical solutions in development in JavaScript, React, Node.js, and related technologies.

A personal WordPress website, where I customized the template to achieve unique design and responsiveness for mobile devices. I set up WordPress plugins to improve website performance and search engine optimization.

Get a URL's preview data (title, description, image, and domain name). I built this Node.js library that uses a Puppeteer headless browser to scrape the website and get the website's title, description, image, and others.

Neo Transfer allows you to log in with a private key, see balance, and transfer NEO or GAS within TestNet. The project is based on the JavaScript SDK for the NEO blockchain. The front end is implemented in React.

Newsfeed for events on crypto goods. A single, responsive page for the newsfeed. Polling occurs every 15 seconds for new events to update the newsfeed in real-time. This front-end project was built using JavaScript, React, Redux, Redux-Saga, and Twitter Bootstrap.

User authentication in a single-page application with Node.js, React, Redux, and Koa combined with Passport.

https://andrejgajdos.com/authenticating-users-in-single-page-applications-using-node-passport-react-and-redux/

Development tools: JavaScript, Node.js, React, Redux, Passport.js.

jQuery DataTables plugin for rendering nested data tables in rows. Inner tables are independent of the data and layout from the outer table. I created this plugin for a data management product.

Development tools: JavaScript and jQuery.

Webpack configuration to bundle ES6, React, Sass, and Bootstrap for production and development.

https://andrejgajdos.com/setting-up-webpack-for-es6-react-sass-and-bootstrap/

Development tools: JavaScript, React, and Webpack.

A Liferay portlet to visualize a social network as a directed multigraph. Jung library is used for building the multigraph, which is stored in OrientDB. Visualization and other components are built in D3.js and Bootstrap.

Development tools: Java, JavaScript, Liferay, JSP, Jung, OrientDB, D3.js, Bootstrap

A workflow converts SVG sprite into PNG images utilizing Gulp.

https://andrejgajdos.com/how-to-convert-svg-sprite-into-png-images/

Development tools: JavaScript, Gulp

Implementation of server push messages from server to client in GWT application with Errai framework.

https://andrejgajdos.com/first-steps-with-gwt-and-errai-messaging/

Development tools: Java, GWT, Errai

Some insurance brokers have a list of insurances and clients in XLS format and need to generate various contracts based on a contract template in DOC and DOCx format. The user can set up a database (XLS or XLSx) and required columns, which will be parsed into the contract. The application has a database of insurance in SQLite. The main window contains a list of clients with detailed information, where the user can instantly search clients, add required information (date, overpayment, insurance from database), choose contract templates, and generate a contract (DOC or DOCx) for the client. The UI is built in WPF and ADO.NET is used for parsing data from a Microsoft Excel file.

Development tools: C#/.NET, WPF, SQLite, ADO.NET

A basic personal calendar application with two view modes (week/month). The application generates log files and uses a MySQL database. The presentation layer is built in Swing and SwingWorker. Connections to the database are developed in JDBC. The project contains simple JSP pages for viewing a list of events and their detailed information.

Development tools: Java, JSP, Swing, SwingWorker, MySQL, JDBC