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Tomasz Stefaniak
Verified Expert in Engineering
Software Developer
San Francisco, CA, United States
Toptal member since June 19, 2017
Bio
Tomasz is a full-stack engineer passionate about web development. He specializes in JavaScript frameworks (Node.js, Express.js, React, Redux, and Vue). Before entering the JavaScript ecosystem, he developed iOS and Android apps. Tomasz has worked in teams and on solo projects and knows the importance of good communication. Having studied at a world-class university in London, he's very comfortable with the English language.
Portfolio
Freelance Clients
Vue 3, Pinia, TypeScript, React, Chrome Extensions, Redux...
Polygon
Vue, Vuetify, Nuxt.js, SCSS, TypeScript, Python, CSS3, HTML5, Cypress...
GRG Studios
React, Vue, Next.js, Sass, TypeScript, JavaScript, Redux, CSS3, HTML5...
Experience
- React - 7 years
- JavaScript - 7 years
- TypeScript - 5 years
- Redux - 4 years
- CSS3 - 4 years
- Vue - 3 years
- React Router - 2 years
- Python - 2 years
Work Experience
Software Engineer
2023 - PRESENT
Freelance Clients
- Developed a custom Vue/Vuetify/Pinia front end and wrote automated Cypress tests to provide stability for its core functionalities.
- Fixed multiple bugs and added new functionalities to a complex Chrome extension written in React used by a VC company to research thousands of startups.
- Migrated a complex Chrome extension used by a VC company to research thousands of startups from JavaScript to TypeScript.
- Developed a React dashboard and configured an Amazon Timestream database with an AWS AppSync back end for an IoT company. Also set up DynamoDB schemas and worked with AWS IoT messages.
Technologies: Vue 3, Pinia, TypeScript, React, Chrome Extensions, Redux, Application State Management, Design Systems, Web Usability, Material UI, Vuetify, AWS Amplify, Azure Functions, Serverless, API Development, Back-end Development, Amazon Web Services (AWS), AWS Lambda, CSS, Node.js, Cypress, Web Applications, Web Dashboards, Test Case Development, AWS IoT, API Integration, Amazon DynamoDB, Figma
Full-stack Engineer | Tech Lead
2021 - 2023
Polygon
- Oversaw the development of multiple front-end libraries.
- Set up the front-end tests and integrated them into a CI/CD pipeline, improving the app's stability and significantly fewer user-facing bugs.
- Helped refactor FastAPI back-end code to follow best practices.
Technologies: Vue, Vuetify, Nuxt.js, SCSS, TypeScript, Python, CSS3, HTML5, Cypress, JavaScript, Git, Visual Studio Code (VS Code), CSS, Sass, Webpack, Responsive Web Apps, Team Leadership, Web Development, Responsive UI, GitHub, Front-end, Full-stack, WebSockets, HIPAA Compliance, User Experience (UX), User Interface (UI), APIs, REST, HTML, SQL, Design, Technical Leadership, Project Management, API Integration, Google SEO, SEO Tools, Seos, Amazon Web Services (AWS), Admin Panels, Amazon S3 (AWS S3), Dashboards, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Front-end Development, Responsive Layout, Full-stack Development, Web UX, REST APIs, Mobile, Remote Team Leadership, Code Review, ECMAScript (ES6), Zapier, Google Analytics, AWS Lambda, UI Components, Kanban, UX Design, CI/CD Pipelines, HubSpot CRM, Architecture, Software Architecture, Application State Management, Design Systems, Web Usability, Node.js, Back-end, Docker, Scheduling, API Development, Back-end Development, Vue SSR, Technical SEO, Web Applications, Web Dashboards, Leadership, Test Case Development, GitHub Actions, Figma
Tech Lead | Software Engineer
2020 - 2021
GRG Studios
- Contributed to a range of projects, mostly relying on React, TypeScript, Next.js, and Vue.
- Managed the hiring process for multiple software development positions, then led the new developers in high-stakes projects.
- Managed developers from 3rd-party companies and coordinated multiple high-stakes projects.
Technologies: React, Vue, Next.js, Sass, TypeScript, JavaScript, Redux, CSS3, HTML5, React Router, Jest, Management, BEM, Git, Visual Studio Code (VS Code), CSS, SCSS, Webpack, Responsive Web Apps, Team Leadership, Web Development, Responsive UI, GitHub, GitLab, Front-end, Full-stack, User Experience (UX), User Interface (UI), APIs, REST, HTML, MERN Stack, Technical Leadership, Project Management, API Integration, Google SEO, SEO Tools, Seos, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Front-end Development, Responsive Layout, Web UX, REST APIs, Mobile, Remote Team Leadership, Code Review, ECMAScript (ES6), Google Analytics, Kanban, UX Design, CI/CD Pipelines, Architecture, Software Architecture, Web Usability, Node.js, Vercel, Technical SEO, Web Applications, Leadership, Figma
Software Engineer via Toptal
2019 - 2021
MintDice
- Developed the front end for a cryptocurrency gaming website used by over 100,000 visitors.
- Set up automated testing with Jest to improve the app's stability and prevent customer-facing bugs.
- Migrated the website from a static website to Next.js to optimize performance.
- Optimized SEO using JSON-LD and React Helmet library.
- Built a blog connected to a CMS and created a custom React component for rendering blog content.
Technologies: TypeScript, React, JavaScript, CSS3, HTML5, Redux, React Router, Jest, Next.js, Material UI, Styled-components, JSON-LD, Sockets, Git, Visual Studio Code (VS Code), CSS, Sass, SCSS, BEM, Webpack, Responsive Web Apps, React DnD, Web Development, Responsive UI, GitHub, GitLab, Front-end, WebSockets, User Experience (UX), User Interface (UI), APIs, REST, HTML, MERN Stack, Design, Technical Leadership, Project Management, API Integration, Google SEO, SEO Tools, Seos, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Front-end Development, Responsive Layout, REST APIs, Mobile, Remote Team Leadership, Code Review, Casino Games, ECMAScript (ES6), UI Components, Kanban, CI/CD Pipelines, React Redux, Material Design, Application State Management, Web Usability, Back-end, React Testing Library, Technical SEO, Web Applications, Test Case Development
Front-end Developer | Tech Lead
2019 - 2019
Pioner Labs
- Helped develop the front end of an eCommerce store for a leading Norwegian fashion retailer.
- Worked extensively with React Hooks, functional components, and TypeScript to build reusable storefronts.
- Contributed to an internal library of reusable React components used to develop storefronts.
- Served as a tech lead for a back-office product, managing online and offline promotional campaigns.
- Selected for an internal leadership coaching program.
Technologies: Node.js, TypeScript, React, JavaScript, CSS3, HTML5, GraphQL, Redux, React Router, Jest, Management, Git, Visual Studio Code (VS Code), CSS, Sass, SCSS, Responsive Web Apps, Team Leadership, Web Development, Responsive UI, GitHub, Front-end, User Experience (UX), User Interface (UI), APIs, REST, HTML, MERN Stack, Technical Leadership, Project Management, API Integration, Admin Panels, Dashboards, Front-end Development, Responsive Layout, Full-stack Development, REST APIs, Mobile, Remote Team Leadership, Code Review, ECMAScript (ES6), UI Components, Storybook, Kanban, CI/CD Pipelines, React Redux, Design Systems, Web Usability, Back-end, Prisma, Web Applications
Front-end Engineer
2018 - 2019
Paladin
- Built multiple customer-facing features for a legal tech product used by lawyers to provide pro-bono services. Built using React, Redux, and Material UI.
- Collaborated closely with the core team and the CTO to address bugs and improve user experience.
- Contributed to the Django/Python back end for the customer dashboard and admin panel.
Technologies: React, HTML, CSS, JavaScript, Git, Material UI, Python, Django, SaaS, Web Applications, Web Dashboards
Front-end Engineer
2017 - 2019
Freelance Clients
- Built a ticket booking service using React and Mapbox for a Mexican travel agency.
- Created and adjusted multiple Shopify stores for various clients.
- Developed a complex React and Redux application from scratch for a company in the gaming and gambling industry.
- Helped document a complex React front end for a cryptocurrency company.
- Built a Vanilla HTML and CSS website for a company in the entertainment industry. This was used as a landing page to drive ticket sales for a series of concerts.
Technologies: Leaflet, Mapbox, React, TypeScript, Liquid, Shopify, JavaScript, eCommerce, MongoDB, Git, CSS, Sass, jQuery, SCSS, Redux-Saga, Responsive Web Apps, GraphQL, React DnD, Web Development, Responsive UI, GitHub, Front-end, User Experience (UX), User Interface (UI), APIs, REST, HTML, MERN Stack, Design, Project Management, API Integration, Google Cloud, Admin Panels, Dashboards, Search Engine Optimization (SEO), Front-end Development, Responsive Layout, Full-stack Development, Web UX, REST APIs, Mobile, Code Review, Casino Games, ECMAScript (ES6), Zapier, Kanban, Google Cloud Platform (GCP), Application State Management, Web Usability, Mapbox API, Web Applications, SOAP
Co-founder | Full-stack JavaScript Developer | CTO
2016 - 2017
Bazzah
- Built an interactive map of independent fashion design and gourmet food producers in Rio de Janeiro as an MVP of an online marketplace platform using Meteor, MongoDB, and React.
- Developed a producer-facing dashboard for managing products, orders, and money withdrawals.
- Created a quick set-up service with six steps (breadcrumbs) to ensure all new sellers have their profiles completely filled in and have at least one product to sell before being approved on the marketplace.
Technologies: MongoDB, Mapbox, ECMAScript (ES6), SCSS, React Router, Redux, React, Meteor, JavaScript, CSS3, Vue, Git, CSS, Responsive Web Apps, Web Development, Responsive UI, GitHub, Front-end, Full-stack, User Experience (UX), User Interface (UI), APIs, REST, HTML, Design, Technical Leadership, Project Management, API Integration, Admin Panels, Dashboards, Front-end Development, Responsive Layout, Minimum Viable Product (MVP), Web UX, REST APIs, Mobile, Code Review, Google Analytics, Kanban, UX Design, Architecture, Software Architecture, React Redux, Application State Management, Web Usability, Mapbox API, NoSQL, API Development, Web Applications, Leadership
Project Manager
2015 - 2016
NUMA Paris
- Supported the startup accelerator team as a project manager in processing and analyzing hundreds of startup applications.
- Analyzed past application data and created tools for internal use, such as a searchable database of startups or a tool for startup evaluation. This was used to rate hundreds of startups, some of which the company eventually invested in.
- Organized the kick-off event for a new startup class.
Technologies: React, Meteor, CSS, HTML, PHP, Responsive UI, JavaScript, GitHub, Front-end, Full-stack, User Interface (UI), Design, Project Management, API Integration, Front-end Development, Responsive Layout, Web UX, REST APIs, Mobile, Zapier, Kanban, UX Design, Web Applications
iOS Developer | Co-founder
2014 - 2015
Ocean London
- Helped develop a Swift/iOS app to assess the user's psychological profile and then rate places in London and add them to our database.
- Designed a recommendation algorithm using a version of the Big Five Personality Test and employing a linear regression algorithm and a rating system to map the psychological profile to user preferences.
- Managed 3rd-party outsourcing companies contracted to develop the applications' back-end.
Technologies: Xcode, Swift, Objective-C, Design, Mobile Development, Technical Leadership, Project Management, API Integration, Mobile Apps, Front-end Development, Responsive Layout, Minimum Viable Product (MVP), Web UX, REST APIs, Mobile, Code Review, iOS, Kanban, UX Design, Architecture, Software Architecture, Leadership
Project History
Panda HSK
Panda HSK is a Chinese learning app that I've designed and coded. It offers three study modes for practicing the words and phrases that appear in the HSK 1 Chinese exam. It's built with React Native, Redux, and TypeScript.
Rank Anything
A website where users create tier lists and other users vote on them. You can find out what's best or worst in any category.
The website is integrated with the Firebase SDK, with email and SMS verification. It was built with Next.js, Tailwind CSS, and PostgreSQL.
The website is integrated with the Firebase SDK, with email and SMS verification. It was built with Next.js, Tailwind CSS, and PostgreSQL.
Sanity Media
A social network built with Next.js, React, Redis, MongoDB, OpenAI, and Amazon Cognito. It's a side project that I developed in my free time. The mechanics are similar to Twitter, except there is a minimum, instead of a maximum, character count, and users are only allowed to post once a day to encourage thoughtful discussion. There is also a live chat.
Emojify 🎉
Emojify was an emoji-based URL shortener. It let you shorten links using one of 75 single-emoji domains such as http://🦍.tk, http://🍾.cf, http://🍹.cf etc. It was featured on the front page of Product Hunt.
It was built with React and React Router for the front end. On the back end, it used Node.js with Express.js and Mongoose. It offered 75 different domains and was hosted on Google Cloud buckets.
It was built with React and React Router for the front end. On the back end, it used Node.js with Express.js and Mongoose. It offered 75 different domains and was hosted on Google Cloud buckets.
Bazzah Producer Panel
Bazzah is an online marketplace for independent fashion producers. The producers use the panel to manage their stores with the ability to add and edit products, product images, and prices. Users can also edit store descriptions, logos, and cover images, and see their account balances and request the withdrawal of funds.
Chilla
A location-based news app built with React Native that allows users to create photo stories and others to react to other users' stories with emojis. I used Node.js with Mongoose and MongoDB with geospatial queries for the back end and implemented anonymous user accounts with Passport.js and Firebase.
Flowcat
Flowcat allows you to pass data between AI models to create reproducible data transformation pipelines. This is still a work in progress.
For example, you can generate an image with one model, modify it with another model, and then remove the background with yet another one.
For example, you can generate an image with one model, modify it with another model, and then remove the background with yet another one.
Education
2012 - 2015
Bachelor's Degree in Arts and Sciences: Sciences and Engineering
University College London (UCL) - London, UK
Certifications
DECEMBER 2019 - PRESENT
Management Essentials
Harvard Business School Online
Skills
Libraries/APIs
Node.js, Vue, React, Liquid, React Router, REST APIs, React Redux, Vue 3, React Testing Library, Recompose, jQuery, Redux-Saga, Leaflet, Sockets, React DnD, Firebase Web SDK, AWS Amplify, Mapbox API, API Development
Tools
GitHub, Webpack, Adobe Illustrator, GitLab, Seos, Google Analytics, Git, Xcode, Zeplin, Mongoose, Firebase Authentication, Expo, Amazon Cognito, Zapier, Prisma, AWS SDK, Figma
Languages
ECMAScript (ES6), HTML, CSS, TypeScript, CSS3, JavaScript, SCSS, HTML5, Python, GraphQL, PHP, Objective-C, Less, Sass, Swift, SQL, Markdown
Frameworks
Redux, Next.js, React Native, Jest, Vuetify, Nuxt.js, Cypress, Material UI, Tailwind CSS, Express.js, iOS SDK, Django, Vue SSR
Paradigms
Kanban, BEM, Agile, Management, REST, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Responsive Layout, HIPAA Compliance, Mobile Development, Web UX Design, UX Design
Platforms
Mobile, Vercel, Visual Studio Code (VS Code), Shopify, Amazon Web Services (AWS), OS X, Heroku, iOS, Meteor, Mapbox, Firebase, Android, Azure, AWS Lambda, Google Cloud Platform (GCP), Azure Functions, Docker, DigitalOcean, AWS IoT
Industry Expertise
Project Management
Storage
NoSQL, MongoDB, Databases, JSON-LD, Cloud Firestore, Google Cloud, Amazon S3 (AWS S3), Redis, PostgreSQL, Amazon DynamoDB
Other
Responsive Web Apps, Web Development, Responsive UI, Front-end, User Interface (UI), API Integration, Front-end Development, Code Review, UI Components, Web Applications, eCommerce, Team Leadership, Full-stack, WebSockets, User Experience (UX), APIs, Airtable, MERN Stack, Technical Leadership, Google SEO, SEO Tools, Mobile Apps, Admin Panels, Dashboards, Full-stack Development, Minimum Viable Product (MVP), Web UX, Remote Team Leadership, Casino Games, CI/CD Pipelines, Architecture, Software Architecture, Application State Management, Design Systems, Web Usability, Back-end, Serverless, SaaS, Technical SEO, OpenAI GPT-4 API, Web Dashboards, Leadership, Test Case Development, Machine Learning, Styled-components, Design, Cross-platform App Development, Storybook, HubSpot CRM, Artificial Intelligence (AI), Material Design, Pinia, Chrome Extensions, Videos, Scheduling, Back-end Development, OpenAI, Vercel Analytics, SOAP, Generative Artificial Intelligence (GenAI), GitHub Actions
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