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Stanislav Kovalev
Verified Expert in Engineering
Software Developer
Ryazan, Ryazan Oblast, Russia
Toptal member since August 9, 2016
Bio
With over 10 years of experience, Stanislav specializes in TypeScript, React, and Ruby on Rails. Having built everything from landing pages to huge SaaS apps, he operates with a staff-engineer mindset. He focuses on establishing foundational architectures and defining strict best practices to ensure highly scalable and maintainable web applications.
Portfolio
Purchasing Platform
TypeScript, React, MobX, Ruby on Rails (RoR), Ruby, Docker, PostgreSQL, CircleCI
Zerno.io
Material UI, React, Redux, Ruby on Rails (RoR), Ruby, MySQL, Docker, Node.js
Adplatform.io
Webpack, SCSS, AngularJS, Machine Learning
Experience
- JavaScript - 10 years
- CSS - 6 years
- Ruby on Rails (RoR) - 6 years
- React - 5 years
- React Query - 4 years
- Redux - 3 years
- Scrum - 3 years
- jQuery - 3 years
Preferred Environment
MacOS, Zed, Claude Code, OpenCode, Cursor AI, Codex
The most amazing...
...tool I've built was a real-time ML module. Trained in Scikit-learn/Keras and rebuilt in C++ to deliver fast, complex insights with zero app lag.
Work Experience
Senior Software Engineer
2019 - PRESENT
Purchasing Platform
- Contributed to a web app's seamless migration from Ruby on Rails to RoR API and React.
- Handled the front-end part of the CI/CD flow and introduced front-end testing practices using Jest and react-testing-library.
- Mentored new team members and set up development guidelines.
- Initiated the app's seamless migration to TypeScript.
- Supported an enormous amount of legacy code from jQuery and React v.13.
Technologies: TypeScript, React, MobX, Ruby on Rails (RoR), Ruby, Docker, PostgreSQL, CircleCI
Full-stack (RoR and React) Developer
2018 - 2019
Zerno.io
- Developed the back-end and services with Docker to provide easy deployments.
- Constructed the front-end with the recent Material UI framework.
- Built a mobile-first app design with the aim to have a React Native app.
Technologies: Material UI, React, Redux, Ruby on Rails (RoR), Ruby, MySQL, Docker, Node.js
Software Developer
2017 - 2019
Adplatform.io
- Refactored legacy AngularJS code to modern standards, significantly improving application modularity and reducing debugging time.
- Modernized the application build pipeline by migrating from Gulp to Webpack, enabling faster deployments and streamlining developer workflows.
- Implemented Cypress testing for critical user paths, significantly improving overall platform stability.
- Drove 5% revenue growth by building predictive ML models with Scikit-learn and Keras, alongside developing a high-speed C++ prediction module.
Technologies: Webpack, SCSS, AngularJS, Machine Learning
Front-end Software Developer
2016 - 2017
Client Project (via Toptal)
- Worked as a remote front-end developer.
- Built an iOS app using React-Native and Redux.
- Supported the architecture design.
Technologies: Redux, React, React Native, JavaScript
Software Engineer
2015 - 2016
Nitka Technologies
- Developed new modules for the NetSuite system.
- Refactored and supported old modules.
- Integrated the codebase with other developers.
- Worked on a NetSuite customization.
- Improved the legacy code to be more modular and supportable.
Technologies: jQuery
Software Engineer
2014 - 2015
EPAM
- Worked on an internal SaaS application for grabbing and presenting development team performance statistics; it was based on AngularJS and D3.js. The app had to perform with different types of data in graphical form (company, department, and team velocity/quality metrics).
- Handled and was responsible for architecture decisions and also mentored two junior developers.
- Worked as a development team lead on a workforce management system based on AngularJS.
- Managed and was responsible for setting tasks for team members.
- Coordinated between the customers, QA, and BA.
- Performed code reviews and gave support.
- Developed new modules and made architectural decisions.
Technologies: JavaScript, Scrum
Web Developer
2013 - 2014
Cherryline
- Developed a few websites for local businesses with PHP and jQuery.
- Worked on a SaaS application for an auto insurance company based on Ruby on Rails and Backbone.js.
Technologies: Ruby on Rails (RoR), Ruby, jQuery, JavaScript, CSS, HTML
Experience
Adplatform.io
https://adplatform.io/An advertising platform built with AngularJS on the front end. It has a modular structure that allows the use of the same codebase for the various accounts (admin, manager, and publisher). The main aim of the accounts' cabinets is to provide a comfortable way to analyze advertising campaign data, so there are a lot of data tables and a sophisticated reports system.
Purchasing Platform
A B2B eCommerce application where I was responsible for a huge variety of tasks, from supporting a CI/CD system to back-end and front-end development and supporting legacy front-end code. I was a frontend-focused senior full-stack developer on the project.
Skills
Libraries/APIs
MobX, React, jQuery, React Query, React Redux, Node.js
Tools
Webpack, CircleCI, JSX, Zed, Claude Code, OpenCode, Codex
Languages
JavaScript, TypeScript, HTML, SCSS, CSS, Ruby
Frameworks
Material UI, Redux, React Native, Ruby on Rails (RoR), Ruby on Rails 5, AngularJS
Paradigms
REST, Scrum, Unit Testing
Platforms
Docker, MacOS
Storage
MySQL, PostgreSQL
Other
Design Principles, CI/CD Pipelines, Machine Learning, Cursor AI
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