Available to hire
I’m Thomas Känzig, a senior full-stack web developer based in Vienna, Austria. I design and build scalable web applications, focusing on frontend architecture with React, TypeScript, and reusable UI components, while also defining robust backend APIs with Node.js, PHP, and Symfony. I work remotely with cross-functional teams across Europe to deliver end-to-end solutions and apply Atomic Design to create cohesive, scalable UI systems.
I enjoy turning complex requirements into clean, maintainable code, mentoring teammates, and delivering high-quality software quickly through automated testing, containerization, and CI/CD practices. I’m always learning and adapting new methodologies to achieve strong project outcomes and measurable impact.
Skills
Experience Level
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Intermediate
Intermediate
Intermediate
Intermediate
Intermediate
Language
English
Fluent
German
Fluent
Portuguese
Fluent
Work Experience
Senior Frontend Developer at Logic Joe GmbH
April 1, 2025 - PresentCreated and maintained reusable component libraries using Storybook, improving development efficiency and consistency across projects. Participated in code reviews and CI workflows via Docker and Git. Used Jira for sprint planning and task tracking; collaborated with cross-functional teams. Provided ongoing support including bug fixes, system updates, and performance optimization to ensure reliable and high-performing applications. Technologies: React.js, Next.js, JavaScript/TypeScript, Storybook, Jira, Docker.
AI Data Trainer - Frontend Focus (Freelance, Remote) at SuperAnnotate AI, Inc
March 20, 2025 - September 23, 2025Created high-quality AI training content by developing frontend-related coding prompts and responses to improve model understanding of JavaScript, HTML and CSS. Focused on UI/UX challenges such as responsive design improvements and integrating third-party libraries; optimized styles and layouts to simulate real-world web tasks. Ensured precise and consistent data labeling following detailed guidelines; used annotation platforms and tools to train AI systems in recognizing clean, accessible code. Collaborated with AI teams to refine annotation workflows and multilingual content (including German). Technologies: HTML, CSS, JavaScript, TypeScript, Selenium, Playwright, UI Kit, Jira.
Senior Full-Stack Web Developer (Remote) at Sprad Software GmbH
September 30, 2024 - September 23, 2025Created and maintained reusable component libraries using Storybook, improving development efficiency and consistency across projects. Participated in code reviews and continuous integration workflows via Docker and Git, contributing to code quality and maintainability. Actively used Jira for sprint planning, task tracking, and agile collaboration with cross-functional teams. Provided ongoing support including bug fixing, system updates, and performance optimization to ensure reliable and high-performance applications. Technologies: React.js, Next.js, PostCSS, JavaScript, TypeScript, Storybook, Jira, FirstSpirit CMS and Docker.
Intermediate Web Developer at Massive Art Web Services GmbH
May 31, 2022 - September 23, 2025Configured and deployed web applications, ensuring they met project specifications and client requirements for a diverse range of applications. Developed new features and implemented enhancements, improving functionality and user experience across multiple projects. Provided ongoing support including bug fixes, system updates, and performance optimization to ensure reliable and high-performing applications. Worked closely with design and product teams to ensure UI improvements aligned with business objectives. Technologies: Symfony, Sass/SCSS, Bootstrap, JavaScript, TypeScript, jQuery, ReactJS, PHP, MySQL, Docker.
Full-Stack Web Developer at Ágil Tributaría
March 31, 2018 - September 23, 2025Promoted from Junior to Mid-Level Web Developer in the first year; played a key role supporting an e-commerce platform for mobile; developed new features, implemented system updates, and resolved bugs to improve functionality and user experience. Collaborated closely with design and product teams to ensure alignment with business goals.
Full-Stack Web Developer at Global Tecnologia
June 30, 2016 - September 23, 2025Contributed to the development of fiscal and financial systems for the Government of Alagoas; improved user interfaces, functionality, usability, and overall user experience. Diagnosed and resolved application bugs, ensuring high performance, stability, and reliability across the platform. Technologies: AngularJS, PHP, MySQL, Bootstrap, and JavaScript.
Researcher at National Council for Scientific and Technological Development (CNPQ)
June 30, 2016 - September 23, 2025Led the development of an academic forecasting platform designed to analyze and predict optimal sugarcane harvest times; implemented neural network algorithms (back-propagation) in PHP, collecting and training data to improve prediction accuracy. Developed a user-friendly frontend and robust backend using modern web technologies, enabling seamless interaction and large data processing.
AI Data Trainer - Frontend Focus at SuperAnnotate AI, Inc
January 1, 2025 - March 1, 2025Created high-quality AI training content by developing frontend-related prompts and responses to enhance model understanding of programming languages. Focused on UI/UX challenges, integrating third-party libraries, and optimizing layouts to simulate real-world web development tasks. Collaborated with AI teams to refine annotation workflows and support multilingual content creation (German).
Senior Full-Stack Web Developer at Sprad Software GmbH
August 1, 2022 - September 1, 2024Created and maintained robust frontend and backend solutions, leveraging modern stacks to deliver features with high quality and consistency. Engaged in code reviews and ongoing integration workflows via Docker and Git, contributing to code quality, performance, and reliability across projects. Worked closely with design and product teams to align UI/UX with business goals.
Intermediate Web Developer at Massive Art Web Services GmbH
March 1, 2019 - May 1, 2022Configured and deployed web applications, implemented new features and enhancements to improve functionality and user experience across multiple projects. Provided ongoing support, bug fixes, system updates, and performance optimizations to ensure reliable, high-performing applications. Collaborated with design and product teams to ensure UI enhancements align with business goals.
Full-Stack Web Developer at GOL AB TRIBU TÁRIA - Maceió
June 1, 2017 - March 1, 2018Developed and implemented new features for finance-focused SaaS platforms, enhancing functionality and user experience. Provided ongoing support, bug fixes, and system maintenance to ensure reliable software performance. Collaborated with design and product teams to ensure UI improvements align with business goals.
Full-Stack Web Developer at GLOBAL TECNOLOGIA - Maceió
October 1, 2015 - June 1, 2016Contributed to the development of fiscal and financial systems for government use, delivering solutions that supported critical government functions. Improved UI/UX and implemented new features to enhance system functionality and overall user experience. Diagnosed and resolved application bugs to ensure high performance, stability, and reliability.
Researcher at National Council for Scientific and Technological Development (CNPQ) - CNPQ - Maceió
October 1, 2015 - June 1, 2016Led the development of an academic forecasting platform to analyze and predict optimal sugarcane harvesting times, improving agricultural decision-making. Implemented neural network algorithms (backpropagation) in PHP, collecting and training data to improve predictive accuracy. Built a user-friendly interface and robust backend to ensure seamless interaction with large datasets.
Senior Full-Stack Web Developer (Remote) at Sprad Software GmbH
August 1, 2022 - September 1, 2024Helped transform legacy PHP and vanilla JavaScript code into a modern architecture using Symfony and web components in TypeScript, implementing tests to improve maintainability and performance. Developed and implemented features for a recruitment platform, significantly enhancing functionality and user experience. Took on additional DevOps responsibilities, streamlining deployment processes and enabling seamless integration of applications. Technologies: Symfony, TypeScript, SCSS, UI Kit, JavaScript, Vue.js, PHP, MySQL, Docker.
Full-Stack Web Developer at Agil Tributária
June 1, 2017 - March 1, 2018Developed and implemented new features for finance-focused SaaS platforms; improved functionality and user experience. Provided ongoing support including troubleshooting, bug fixes, and system maintenance to ensure reliable software performance. Contributed to development and optimization of various finance systems used by clients for tax and financial management. Technologies: PHP, MySQL, HTML5, CSS3 (Sass), JavaScript (with jQuery).
Full-Stack Web Developer at B&B Produções e Eventos
January 1, 2011 - April 1, 2015Promoted from junior to mid-level Web Developer in the first year, rapidly developing skills and increasing responsibilities. Played a key role in supporting and enhancing an e-commerce platform for mobile devices, developing new features, implementing system updates, resolving bugs to improve functionality and user experience. Collaborated closely with design and product teams to ensure alignment between UI improvements and business goals. Technologies: HTML, CSS, Bootstrap, JavaScript (jQuery), PHP, MySQL.
Full-Stack Web Developer at Global Tecnologia
October 1, 2015 - June 1, 2016Contributed to the development of financial and government-focused systems, delivering solutions that supported critical government functions. Improved UI/UX and overall system functionality, usability, and reliability across the platform. Technologies: HTML, CSS, Bootstrap, JavaScript (with jQuery), PHP, MySQL.
Researcher at CNPQ - National Council for Scientific and Technological Development
October 1, 2015 - June 1, 2016Led the development of an academic forecasting platform designed to analyze and predict optimal sugarcane harvest times, enhancing agricultural decision-making. Researched and implemented neural network algorithms (backpropagation) in PHP, collecting and training data to improve prediction accuracy. Built a user-friendly interface and a robust backend to support seamless interaction and large data processing. Applied AI principles to optimize predictive capabilities, contributing to advances in agricultural technology. Technologies: CakePHP, MySQL, HTML, CSS, Bootstrap, JavaScript (with jQuery).
Founder | Senior Full-Stack Developer at Speak with Native
November 1, 2025 - PresentFounded and built Speak with Native, a language-exchange platform connecting learners with native speakers worldwide. Developed web + mobile apps using React, React Native, TypeScript, Symfony (PHP), and MySQL, owning architecture and end-to-end implementation. Designed REST APIs and database schema for messaging, user discovery/matching, community features, and subscriptions. Shipped monetization flows including premium onboarding and feature gating. Improved product quality and delivery velocity through automated testing (Playwright, PHPUnit), containerized environments (Docker), and iterative performance/UX enhancements.
Senior Full-Stack Web Developer at Spread Software GmbH
August 1, 2022 - September 1, 2024Helped transform legacy code written in PHP and vanilla JavaScript into a modern architecture using Symfony, web components, and TypeScript, implementing tests to improve maintainability and performance. Developed and implemented innovative features for the recruitment platform, significantly enhancing functionality and user experience. Took on additional responsibilities as a DevOps engineer, streamlining deployment processes and enabling seamless integration of apps.
Researcher at National Council for Scientific and Technological Development (CNPQ)
October 1, 2015 - June 1, 2016Led the development of an academic forecasting platform for optimizing sugarcane harvest timing. Researched and implemented neural network algorithms (back-propagation) in PHP, training data to improve prediction accuracy. Developed a user-friendly interface and robust backend to ensure seamless interaction and large data processing.
Senior Full-Stack Web Developer at Speak with Native
November 1, 2025 - PresentDeveloped web + mobile applications using React, React Native, TypeScript, Symfony (PHP), and MySQL, owning architecture and end-to-end implementation while applying Atomic Design principles to build scalable and reusable UI components.
Senior Full-Stack Web Developer at Sparda Software GmbH
August 1, 2022 - September 1, 2024Led full‑stack development using React, Next.js, TypeScript, JavaScript; improved development efficiency, scalability, and UI consistency; performed code reviews and maintained CI workflows; used Docker and Git.
Full-Stack Web Developer at Ágil Tributária
June 1, 2017 - March 1, 2018Developed features for finance-focused SaaS platforms; implemented bug fixes and system maintenance; collaborated with teams to align with business goals.
Education
Bachelor's Degree in Information Systems at Instituto Federal de Alagoas - Maceió, Alagoas, Brazil
January 11, 2030 - January 1, 2016Bachelor's Degree - Information Systems at Instituto Federal de Alagoas - Maceió, Alagoas
January 11, 2030 - January 1, 2016Bachelor's Degree - Information Systems at Instituto Federal de Alagoas - Maceió, Alagoas
January 11, 2030 - January 1, 2016Bachelor's Degree - Information Systems at Instituto Federal de Alagoas (IFAL)
January 1, 2016 - January 1, 2016Bachelor's degree - Information Systems at Instituto Federal de Alagoas - Maceió, Alagoas
January 11, 2030 - January 1, 2016Qualifications
Docker Foundation Professional Certificate
February 24, 2025 - September 23, 2025JavaScript Foundations Professional Certificate
February 8, 2025 - September 23, 2025Playwright: Web Automation Testing From Zero to Hero
October 31, 2024 - September 23, 2025Understanding TypeScript
August 13, 2024 - September 23, 2025React Native - The Practical Guide
January 14, 2025 - September 23, 2025Docker Foundations Professional Certificate – Docker
February 24, 2025 - January 5, 2026JavaScript Foundations Professional Certificate – Mozilla
February 8, 2025 - January 5, 2026React Native - The Practical Guide – Udemy
January 14, 2025 - January 5, 2026Playwright: Web Automation Testing From Zero to Hero – Udemy
October 31, 2024 - January 5, 2026Understanding TypeScript – Udemy
August 13, 2024 - January 5, 2026Docker Foundation
February 24, 2025 - February 11, 2026JavaScript Foundations Professional Certification
February 8, 2025 - February 11, 2026React Native - The Practical Guide
January 14, 2025 - February 11, 2026Playwright: Web Automation Testing From Zero to Hero
October 31, 2024 - February 11, 2026Understanding TypeScript
August 13, 2024 - February 11, 2026Docker Foundation Professional Certificate
January 11, 2030 - April 11, 2026JavaScript Foundations Professional Certificate
January 11, 2030 - April 11, 2026React Native - The Practical Guide
January 11, 2030 - April 11, 2026Playwright: Web Automation Testing From Zero to Hero
January 11, 2030 - April 11, 2026Understanding TypeScript
January 11, 2030 - April 11, 2026Docker Foundations Professional Certificate
February 24, 2025 - May 21, 2026JavaScript Foundations Professional Certificate
February 8, 2025 - May 21, 2026React Native: The Practical Guide
January 14, 2025 - May 21, 2026Playwright: Web Automation Testing From Zero to Hero
October 31, 2024 - May 21, 2026Understanding TypeScript
August 13, 2024 - May 21, 2026Industry Experience
Software & Internet, Media & Entertainment, Professional Services, Government, Education, Financial Services
Skills
Experience Level
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Intermediate
Intermediate
Intermediate
Intermediate
Intermediate
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