Evan is available for hire
Hire EvanEvan Janovsky
Verified Expert in Engineering
React Developer
Haarlem, Netherlands
Toptal member since January 17, 2022
Bio
Evan is a senior full-stack developer with more than 15 years of experience building secure, scalable digital products. He specializes in TypeScript, React, Next.js, Node.js, Supabase, PostgreSQL, AWS, and Azure. Combining strong engineering with product design expertise, he has delivered SaaS platforms, CMS websites, eCommerce solutions, and mobile applications for startups and global organizations.
Portfolio
Actuals
React, React Query, REST APIs, Amazon Web Services (AWS), Charts...
Buur
React, React Query, Supabase, Supabase Auth, Agile, Azure, Security, Stripe...
Touchtribe
React, Next.js, JavaScript, TypeScript, Node.js, HTML, GitLab CI/CD...
Experience
- HTML - 7 years
- JavaScript - 7 years
- CSS - 7 years
- React - 6 years
- TypeScript - 5 years
- Gatsby - 4 years
- React Native - 4 years
- Redux - 4 years
Work Experience
Lead Developer
2026 - PRESENT
Actuals
- Designed the user interface and directed the complete rebuild of a full-scale SaaS fintech application, owning the product experience and technical execution from concept through production release.
- Led the development team across four delivery stages covering planning, implementation, code review, and release while assigning ownership, resolving blockers, and maintaining engineering standards.
- Made key architectural decisions for the React and TypeScript application, including component structure, routing, state management, data flows, testing strategy, and reusable application patterns.
- Defined the technical architecture for three core financial workflows covering data import, transformation, and reconciliation.
- Created a reusable component and page system across six product areas, including overview, credentials, exceptions, journal entries, documentation, and shared financial workflows.
- Redesigned the complete application experience by unifying eight capabilities, including navigation, breadcrumbs, global search, notifications, company switching, view controls, sidebar behavior, and header actions.
- Optimized complex financial data tables for datasets containing millions of transaction records, improving rendering, filtering, pagination, navigation, and overall interface responsiveness.
- Audited AI-assisted code contributions, identified architectural mistakes, incorrect assumptions, type safety problems, and missed edge cases, and implemented production-ready corrections.
- Established three mandatory engineering quality gates through automated testing, static type checking, and linting to catch regressions and improve consistency across the team.
- Translated complex accounting requirements into intuitive product experiences while coordinating technical decisions across product, design, finance, and back-end engineering.
Technologies: React, React Query, REST APIs, Amazon Web Services (AWS), Charts, Dashboard Design, Tables, Shadcn, Technical Leadership, Vercel, CI/CD Pipelines, GitLab CI/CD, RAG Systems, AI-assisted Development, PostgreSQL, Vite, Application State Management, Jest, Google Analytics, Development, Web, CMS, Digital Marketing, Web Design
CTO & Lead Developer
2025 - 2026
Buur
- Architected and developed a multi-tenant PropTech platform using Supabase, PostgreSQL, and modern web technologies for Dutch homeowners’ associations (VvEs).
- Designed the relational database architecture across six core domains: organizations, members, maintenance, meetings, voting, and financial planning.
- Developed responsive production interfaces for five core workflows, including onboarding, maintenance, meetings, voting, and financial planning, across desktop and mobile screen sizes.
- Collaborated across product, design, and engineering to turn complex VvE governance requirements into secure, maintainable production features.
- Implemented secure authentication and role-based authorization for board members and homeowners using Supabase Auth and PostgreSQL Row Level Security policies.
- Enforced tenant-level data isolation so users could access only the associations, documents, financial records, and maintenance requests assigned to them.
- Developed secure document-storage workflows with access policies that protected private meeting, property, and financial files from unauthorized retrieval.
- Built back-end workflows for member onboarding, task assignment, maintenance tracking, meeting management, voting, and financial plan administration.
- Integrated AI-assisted functionality for guided onboarding, meeting summaries, and contextual support while protecting sensitive association and user data.
- Strengthened application security through server-side validation, least-privilege permissions, protected environment variables, and controlled database access.
Technologies: React, React Query, Supabase, Supabase Auth, Agile, Azure, Security, Stripe, Authentication, Full-stack Development, Dashboard Design, Artificial Intelligence (AI), Chatbots, Charts, Agentic AI, Product Design, SaaS, Tables, Shadcn, Technical Leadership, Vercel, Fractional CTO, CI/CD Pipelines, GitLab CI/CD, RAG Systems, AI-assisted Development, PostgreSQL, Lovable, Vite, Application State Management, Jest, REST APIs, Google Analytics, Development, Web, CMS, Digital Marketing, Web Design
Senior Full-stack Developer
2024 - 2026
Touchtribe
- Delivered production applications across three product categories, including SaaS dashboards, CMS websites, and eCommerce platforms.
- Developed responsive interfaces with React, Next.js, JavaScript, and TypeScript for desktop, tablet, and mobile experiences.
- Built reusable component systems that improved interface consistency and accelerated development across multiple client projects.
- Implemented headless CMS solutions using Storyblok and Contentful, enabling content teams to manage pages independently without developer support.
- Integrated front-end applications with commerce platforms, search services, authentication systems, and custom backends through REST and GraphQL APIs.
- Developed complex dashboard interfaces with data visualization, filtering, forms, loading states, error handling, and permission-aware functionality.
- Optimized page rendering, asset delivery, and data fetching to improve Core Web Vitals, loading performance, and perceived responsiveness.
- Applied secure development practices through input validation, controlled data access, safe environment configuration, and dependency management.
- Collaborated with designers, back-end developers, product owners, and client stakeholders throughout planning, implementation, review, and release.
- Maintained code quality through peer reviews, automated checks, testing, clear documentation, and shared engineering standards.
Technologies: React, Next.js, JavaScript, TypeScript, Node.js, HTML, GitLab CI/CD, CI/CD Pipelines, CSS, Tailwind CSS, REST APIs, Angular, GraphQL, Storyblok, Contentful, Headless CMS, Vercel, Git, Security, Agentic AI, APIs, Stripe, Technical Leadership, Tables, Shadcn, Fractional CTO, RAG Systems, AI-assisted Development, PostgreSQL, Lovable, Vite, Application State Management, Jest, Zustand, eCommerce, Google Analytics, Shopify, Development, Web, CMS, Digital Marketing
Front-end React/Next.js Developer
2025 - 2025
Deepnote, Inc.
- Developed several responsive, pixel-perfect pages for Deepnote using React, Next.js, and SCSS, based on existing Figma designs.
- Created reusable custom UI components to maintain visual consistency and support efficient future development.
- Integrated third-party form tools, ensuring they worked seamlessly with the website’s design, validation, and user experience.
- Built responsive layouts that provided a polished experience across desktop, tablet, and mobile devices.
- Applied accessibility and SEO best practices, including semantic markup, keyboard-friendly interactions, and optimized page structure.
- Added subtle animations and micro-interactions to make the pages feel more dynamic and engaging.
- Optimized images and SVG assets to reduce file sizes and improve page-loading performance.
Technologies: React, TypeScript, Next.js, Front-end, GraphQL, Full-stack, Data Science, Charts, Product Design, SaaS, Tables, Vite, Application State Management, Jest, REST APIs, Development, Web
React Developer
2025 - 2025
McCormack Holdings, Inc
- Created a clean, modern website with no design guides.
- Added custom components and a form with validation and sanitization.
- Had iterations with demos to present the progress and receive feedback.
Technologies: JavaScript, Front-end Design, CSS, HTML, React, TypeScript, Forms, HTML Templates, Integrations, Authentication, Charts, Product Design, SaaS, Security, Tables, CI/CD Pipelines, GitLab CI/CD, AI-assisted Development, Vite, Application State Management, Jest, REST APIs, Google Analytics, Development, Web, Web Design
Web Developer
2025 - 2025
Eastern Sierra Perspectives
- Developed a web application that was deployed on Netlify. It fetches data from the Google Sheets API, presents a multi-step form, collects responses, and displays conditional data. Uses Netlify Functions for serverless ops and CSS Grid for layout.
- Integrated Google Sheets API and back-end logic. Implemented a Node.js Express.js server to fetch and process data from the Google Sheets API, ensuring seamless data retrieval and handling for the multi-step form.
- Built a dynamic multi-step UI. Designed and developed a responsive CSS grid layout, implemented form state management, and added logic to display conditional data based on user input, ensuring a smooth user experience.
Technologies: JavaScript, CSS, HTML, Full-stack, Squarespace, Google Sheets API, Netlify, JavaScript 6, Responsive UI, Pixel Perfect, Front-end Design, Forms, HTML Templates, Integrations, Authentication, Charts, Product Design, SaaS, Tables, CI/CD Pipelines, GitLab CI/CD, Application State Management, Jest, REST APIs, Google Analytics, Development, Web, Web Design
Senior Front-end Developer
2022 - 2024
Elements
- Designed the overall architecture of the applications. This included deciding on the component structure, how we managed the state and navigation flows, and how we integrated with back-end services.
- Evaluated and selected the best tools, libraries, and frameworks to optimize the app's performance, maintainability, and scalability.
- Ensured that the team adhered to established coding standards and best practices. This involved emphasizing clean code principles, modularization, and the proper use of design patterns.
- Mentored junior developers, helping them enhance their skills and providing guidance on challenging problems.
Technologies: React, React Native, Redux, HTML, CSS, Next.js, Agile, App Development, Responsive Web Design (RWD), Investing, SaaS Design, User Experience (UX), User Experience Design, User Interface (UI), Angular, D3.js, Design, Front-end Development, UI Libraries, UI Frameworks, React Router, React Query, Amazon Web Services (AWS), React Authentication, Startups, Dashboards, Headless CMS, Mobile App Development, Tailwind CSS, Tailwind UI, Full-stack, Firebase Hosting, QR Codes, JavaScript 6, Responsive UI, Pixel Perfect, jQuery, Payment Gateways, Stripe API, Front-end Design, Forms, HTML Templates, Integrations, Authentication, Charts, Agentic AI, Product Design, SaaS, Security, Tables, Technical Leadership, Vercel, CI/CD Pipelines, GitLab CI/CD, RAG Systems, Vite, Application State Management, Jest, REST APIs, eCommerce, Google Analytics, Shopify, Development, Web, CMS, Digital Marketing, Web Design
Web Developer
2023 - 2023
Re Wood Me
- Developed a booking platform for a calendar reservation project, where certain spaces could be rented out.
- Ran weekly progress meetings to align clients' needs with the budget.
- Developed a complex custom booking application that is lightning fast, type-safe, and includes data caching in a small time frame.
Technologies: JavaScript, HTML, CSS, Web Development, Calendars, React, Firebase, Cloud Firestore, TypeScript, APIs, API Integration, Web Forms, Minimum Viable Product (MVP), Agile, Responsive Web Design (RWD), User Interface (UI), Design, Front-end Development, UI Libraries, UI Frameworks, React Query, Startups, Dashboards, Headless CMS, Full-stack, QR Codes, JavaScript 6, Responsive UI, Pixel Perfect, Front-end Design, Forms, HTML Templates, Integrations, Authentication, Product Design, SaaS, Tables, CI/CD Pipelines, GitLab CI/CD, Application State Management, Jest, REST APIs, Google Analytics, Development, Web, Web Design
Senior Front-end Developer
2021 - 2022
Cartrack
- Designed and developed new fleet fraud management features for the web application.
- Replaced older state management technology like Redux with a more modern approach, such as React Query.
- Optimized the web application's UI/UX design and performance by caching data and refactoring the existing code.
Technologies: React, JavaScript, Redux, APIs, Node.js, HTML5, NPM, Git, TypeScript, Figma, Front-end, Content Management Systems (CMS), HTML Email, Bootstrap, Single-page Applications (SPAs), ESLint, Web Development, App Development, UI Design, UX Design, Data Analysis, Data Visualization, API Integration, DevOps, Web Forms, Minimum Viable Product (MVP), Agile, Responsive Web Design (RWD), SaaS Design, User Experience (UX), User Interface (UI), Design, Front-end Development, UI Libraries, UI Frameworks, Startups, Dashboards, Headless CMS, Tailwind UI, Full-stack, Cloud Firestore, JavaScript 6, Responsive UI, Pixel Perfect, jQuery, Payment Gateways, Front-end Design, Forms, HTML Templates, Integrations, Authentication, Charts, Product Design, SaaS, Security, Tables, CI/CD Pipelines, GitLab CI/CD, Application State Management, Jest, REST APIs, Google Analytics, Development, Web, CMS, Digital Marketing, Web Design
Front-end Developer | Mobile Developer
2020 - 2021
League Digital
- Developed large-scale mobile applications with over a million users.
- Used Firebase to create user authenticated applications with informative statistics about the apps' usage for the clients.
- Oversaw the launch process for the Google Play Store and Apple's App Store.
Technologies: React, React Native, Redux, Firebase, JavaScript, Node.js, HTML5, NPM, Git, TypeScript, Front-end, Content Management Systems (CMS), HTML Email, Bootstrap, Single-page Applications (SPAs), Tailwind CSS, ESLint, Web Development, App Development, Stripe, UI Design, UX Design, APIs, Data Analysis, Data Visualization, API Integration, DevOps, Web Forms, Agile, Responsive Web Design (RWD), SaaS Design, User Experience (UX), User Experience Design, User Interface (UI), Design, Front-end Development, UI Libraries, UI Frameworks, Startups, Dashboards, Headless CMS, Tailwind UI, Firebase Hosting, Cloud Firestore, JavaScript 6, Responsive UI, Pixel Perfect, Payment Gateways, Stripe API, Front-end Design, Forms, SQL, HTML Templates, Integrations, Authentication, Charts, Product Design, SaaS, Security, Tables, Vercel, CI/CD Pipelines, GitLab CI/CD, Application State Management, Jest, REST APIs, eCommerce, Google Analytics, Shopify, Development, Web, CMS, Digital Marketing, Web Design
Front-end Developer | Product Interface Designer
2015 - 2020
BIGBrave
- Created a wide range of web products from business and eCommerce websites to large-scale web platforms.
- Completed all product development stages in collaboration with other developers and corporate teams.
- Handled client briefs, wireframing, UI/UX design, development environments and source control set up, domains and hosting set up, deployment, backups, and maintenance.
- Created static React-based websites with GatsbyJS now featured on the Gatsby website.
Technologies: JavaScript, React, Gatsby, HTML, CSS, Node.js, Netlify, HTML5, NPM, Git, TypeScript, Figma, Front-end, Content Management Systems (CMS), HTML Email, Bootstrap, Single-page Applications (SPAs), WordPress, ESLint, Web Development, App Development, UI Design, UX Design, APIs, Data Visualization, API Integration, DevOps, Web Forms, Agile, Responsive Web Design (RWD), Investing, SaaS Design, User Experience (UX), User Experience Design, User Interface (UI), Design, Front-end Development, UI Libraries, UI Frameworks, Startups, Dashboards, Headless CMS, Mobile App Development, Tailwind UI, JavaScript 6, Responsive UI, Pixel Perfect, jQuery, Payment Gateways, Stripe API, Front-end Design, Forms, SQL, HTML Templates, Integrations, Authentication, Charts, Product Design, SaaS, Security, Tables, Vercel, CI/CD Pipelines, GitLab CI/CD, Application State Management, Jest, REST APIs, eCommerce, Google Analytics, Shopify, Development, Web, CMS, Web Design
Project History
Property Management Software for Buur
https://mijn-buur.nl/Buur is an AI-powered property management platform that helps Dutch homeowners' associations manage their buildings independently. It brings maintenance, tasks, meetings, voting, financial planning, documents, and member communication into one secure and transparent workspace.
Cord Analytics Web Portal
A React-based dashboard platform to simplify the fundamental analysis of publicly traded stocks. I worked as the front-end developer, building the platform from an initial idea to multiple iterations with new features and through the beta testing phase and final production launch. The application includes user authentication, complex charts, tables, caching strategies, state management, and Stripe-based payments.
Estate Management Application
A React-based web application where Estate owners could load and manage their rental properties, units, and tenants and gain valuable insights about them by using the customized dashboard widgets. The tenants used the app to receive invoices, log faults, book familiar and storage places, and read relevant news updates.
Design Review Application
A React and Firebase project that includes role-based authentication, image storage, and firebase. A user can create different questionnaires to receive feedback or review on a project from other users. The user then invites others to join the platform and review and vote on the project options.
Luminarch Website
A React-based static website using GatsbyJS. This website is minimal with great micro animations to give a fantastic user experience. I used image optimization techniques and a content delivery network (CDN) to improve the page load time.
Gamified Internal Communication App for Zimmer Biomet
A React-based platform that allows co-workers to earn points by giving and receiving compliments, logging into the platform, learning more about the companies' products, watching training videos, giving company feedback, or reading company news articles. Co-workers can then spend the points to purchase products from the platform's eCommerce section.
Ebesa Architects Website
https://www.ebesa.co.za/A React/Gatsby responsive portfolio website for Ebesa Architects. The website uses Gatsby's image optimization features to ensure a large number of portfolio images are resized and served as quickly as possible without long loading times. The site includes custom-built image sliders and galleries. It is hosted on Netlify to make use of the CDN to improve page load times worldwide.
Design Review App for LucidTechnics
A React-based app for design reviews or questionnaires. I created a web platform with Firebase and React with TypeScript. Features include role-based user authentication, database crud, Image Uploads, complex form validation, dashboards, and charts, among others.
Emergency Response Web App
A React-based app for emergency response. I created a web platform with Firebase and React with TypeScript. Features include role-based user authentication, database CRUD, QR code creation and download, image uploads, custom SMS and email service integration, complex form validation, dashboards, and more
Skills
Libraries/APIs
React, React Router, React Query, Google Sheets API, REST APIs, Node.js, Stripe, D3.js, Stripe API, jQuery
Tools
GitLab CI/CD, Shadcn, GitHub, Slack, Figma, NPM, Git, Google Analytics
Languages
JavaScript, HTML, CSS, TypeScript, HTML5, JavaScript 6, GraphQL, SQL
Frameworks
React Native, Next.js, Tailwind CSS, Jest, Redux, Bootstrap, Angular
Paradigms
Agile, App Development, UI Design, UX Design, DevOps, Responsive Web Design (RWD)
Platforms
WordPress, Vercel, Web, Firebase, Netlify, Amazon Web Services (AWS), Shopify, Azure, Storyblok, Contentful
Storage
Web Forms, PostgreSQL, Cloud Firestore
Industry Expertise
Web Design
Other
Gatsby, Software Engineering, Software, Front-end, HTML Email, Single-page Applications (SPAs), ESLint, Web Development, Calendars, Data Visualization, API Integration, Responsive UI, Pixel Perfect, User Interface (UI), Web UX, Front-end Development, Startups, Dashboards, Headless CMS, Tailwind UI, Full-stack, Squarespace, Front-end Design, Forms, HTML Templates, Integrations, Authentication, Supabase, Supabase Auth, Product Design, SaaS, Security, Charts, CI/CD Pipelines, Technical Leadership, Tables, AI-assisted Development, Vite, Application State Management, eCommerce, Development, CMS, APIs, Content Delivery Networks (CDN), Content Management Systems (CMS), QR Codes, Full-stack Development, Firebase Hosting, Data Analysis, Minimum Viable Product (MVP), Investing, SaaS Design, User Experience (UX), User Experience Design, Design, UI Libraries, UI Frameworks, React Authentication, Mobile App Development, Payment Gateways, RAG Systems, Fractional CTO, Lovable, Zustand, Digital Marketing, Cloudinary, Data Science, Dashboard Design, Artificial Intelligence (AI), Chatbots, Agentic AI
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