Browse Alexandr Sopilnik's full freelancer profile to see experience, skills and past work — or post a project to receive a tailored proposal.
View Freelancer Profile →I build web, desktop and mobile apps in TypeScript and Rust. Web: React and Next.js with Node.js (Express or NestJS), including online stores with Stripe checkout and an admin panel. Desktop: cross-platform apps with Tauri and Rust. Mobile: React Native apps. I also build Rust backend services, REST APIs and Chrome extensions. 10+ years in IT. I work async and in writing, with no calls.
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I fix bugs in web apps and sites: broken forms and buttons, broken login, layout that fell apart, console errors, a project that stopped building after an update. Stack: JavaScript, TypeScript, Node.js on the server, React and Next.js on the…
People keep asking questions your documents already answer, and a general chatbot invents replies. I build a chatbot that searches your own files, answers from them with the file and page or section, and says so when the answer isn't there.
You need a mobile app that shares logic with your web product, or a first app to test an idea. I build it in React Native with TypeScript for Android and iOS, connect it to your backend, and hand over builds ready for testing and store submission.
If any logged-in user can read other users' rows, your database is trusting the app to behave. I move the rule into PostgreSQL itself with row-level security policies and roles, then prove with tests that one user cannot reach another user's data.
Your app runs on one laptop and deploys by hand. I put it in Docker, add a GitHub Actions or GitLab CI pipeline that tests and builds it on every push, and set up a deploy to your server or platform that runs from the repository.
Your front end still runs on jQuery, old class components or an outdated Next.js setup, and every change takes longer than it should. I move it to modern React or Next.js in TypeScript one page at a time, while the product keeps working.
Orders fail at checkout, a payment method disappeared, shipping costs come out wrong, or the store is only half set up. I fix WooCommerce stores and finish their setup, and I test every change with test orders before your customers see it.
Your WordPress site broke after an update, a plugin fights with the theme, or pages load slowly and nobody knows why. I find the cause, fix it on a copy first where possible, and tell you in plain words what was wrong.
You have a design and a backend, and need the part users actually see. I turn Figma screens into a React or Next.js front end in TypeScript, responsive from phone to desktop, and connect it to your API with loading, empty and error states handled.
Your app works when you click through it, but you are not sure it will hold up with real users and real money. I find what breaks, leaks or blocks the launch in apps built with Lovable, Bolt, Cursor or v0, and fix it in your code without starting over.
I write the backend your app talks to, in TypeScript on Node.js, using Express or NestJS. It can expose a REST API for a web or mobile app, run a worker that handles uploaded files or queue jobs, or connect your app to a third-party API. I use PostgreSQL, MongoDB and Redis for data, and Docker for running it.
You need a website that works on every screen — phone, tablet and desktop — loads fast and is yours afterwards. I build it in React or Next.js, and when it needs a backend I write that too, in Rust or in TypeScript on Node.
Your React or Next.js app got slower one release at a time. The bundle grew, images ship at full size, a third-party script blocks the first paint, a list re-renders on every keystroke. I measure which of those actually costs your users time, then fix the ones worth fixing.
Your extension worked last month and it doesn't now. Chrome shipped an update, the site underneath changed its markup, or it still runs on Manifest V2 and the store won't take it any more. I repair those, in JavaScript and TypeScript.
A browser extension does one job well: a button that saves what you are looking at, a panel that pulls numbers off a page, a shortcut your team uses fifty times a day. I build those in JavaScript and TypeScript on Manifest V3.
I fix bugs in web apps and sites: broken forms and buttons, broken login, layout that fell apart, console errors, a project that stopped building after an update. Stack: JavaScript, TypeScript, Node.js on the server, React and Next.js on the front end, plus plain HTML/CSS/JS and WordPress, including theme and plugin PHP. Not Shopify. I also work with code that was written in a hurry or generated with AI tools.
A desktop application is the right answer when the work happens on the machine and not in a browser: files that never leave the office, a tool the team opens every morning, a window that keeps working when the connection does not. I build those in Rust with the interface in Tauri, so what you install is one small file.
Command line tools in Rust for the jobs that get done by hand every week: converting or validating a file, renaming and sorting in bulk, calling an API and writing the result to CSV or JSON, running on a schedule and reporting what it did. It ships as one binary, nothing to install on the machine that runs it.
Rust REST APIs and backend workers built on axum, delivered to your repository with tests and a README. Fixed scope per tier, written updates, no calls.
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