Iaroslav Sobolev, Developer in Berlin, Germany
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Iaroslav Sobolev

Verified Expert  in Engineering

Software Developer

Berlin, Germany
Toptal Member Since
March 29, 2018

Iaroslav is a professional software engineer who's especially passionate about JavaScript and complex web user interfaces and services. With years of hands-on experience, he has been building web applications and services that also high-load projects, converting complex tasks and engineering problems into software solutions.


GraphQL, Node.js, TypeScript, MikroORM, Agile Project Management, React...
Array, LLC
JavaScript, Front-end, React, LitElement, Next.js...
Expand.org (via Toptal)
Object-oriented Design (OOD), Redux-Saga, Stylus, Babel...




Preferred Environment

Docker, Figma, Sketch, Git, Visual Studio Code (VS Code), MacOS

The most amazing...

...project I've worked on recently is a platform for AI-based data analysis and visualization.

Work Experience

Staff Software Engineer

2022 - 2023
  • Built scalable microservice architecture for edtech project centered around homeschooling. This includes several front-end applications for parents and teachers, an Apollo GraphQL server, and back-end microservices.
  • Streamlined the development process significantly by implementing essential tools and procedures, including CI, code review, linting, and error tracking. Performed onboarding of the new team members.
  • Created an LMS platform that helps staff manage enrollments, classes, teachers, and work samples. Integrated the system with Clever.com, enabling teachers to synchronize data and access the application using Clever.com as their identity provider.
Technologies: GraphQL, Node.js, TypeScript, MikroORM, Agile Project Management, React, Apollo Server, Microservices Architecture, Redis, Google Cloud Platform (GCP), PostgreSQL, MongoDB, Neo4j, Chakra UI, Next.js, Message Queues, GitHub, Full-stack, Storyblok, Tailwind CSS, SQL, Architecture, Technical Architecture, Leadership

Staff Software Engineer

2020 - 2022
Array, LLC
  • Developed a framework for building embeddable widgets using Svelte and web components as core technologies.
  • Led the team of front-end developers responsible for building web components. Contributed to project planning, collaborating with the management.
  • Helped expand the team by conducting interviews, onboarding new team members, and performing code reviews.
Technologies: JavaScript, Front-end, React, LitElement, Next.js, Progressive Web Applications (PWA), Svelte, TypeScript, Node.js, APIs, Monorepos, Sass, Architecture, Technical Architecture, Leadership

Lead Front-end Engineer

2018 - 2020
Expand.org (via Toptal)
  • Developed a front-end application allowing Expand.org clients to execute microtasks.
  • Built a task management application for requesters from scratch, overseeing it from initial planning and design to a successful launch.
  • Developed and open-sourced a React-based UI component library and UIkit used across all company UIs.
  • Constructed a generic form library and visual editor for building microtask UIs.
Technologies: Object-oriented Design (OOD), Redux-Saga, Stylus, Babel, Agile Software Development, Microservices, REST APIs, CSS, Front-end, Jest, Web3.js, Google Cloud, Go, Node.js, Docker, PostCSS, Webpack, Redux, React, GitHub, Web3, APIs, Storyblok, Architecture, Technical Architecture

Senior Front-end Engineer

2017 - 2018
  • Developed public-facing instruments for managing access to the SaaS platform.
  • Created and maintained several libraries used across the company for building scalable front-end applications.
  • Reworked the company's component library (React components) with Lerna and Storybooks.
Technologies: Object-oriented Design (OOD), Babel, GitLab, Agile Software Development, Microservices, REST APIs, CSS, Front-end, TypeScript, Jest, Storybook, Zeplin, Node.js, Docker, PostCSS, Webpack, Redux-Saga, Redux, React, Amazon Web Services (AWS), Monorepos, Sass, Storyblok

Lead Front-end Developer (Contract)

2016 - 2018
  • Designed and implemented from scratch the front-end platform for complex data visualization using React and D3.js.
  • Developed a framework for real-time user notifications.
  • Built applications for marking relationships in data (building an ontology) and representing these relationships in the form of a graph.
  • Created the front end for invoice management application with complex search, filtering, and tagging capacities.
  • Designed and implemented backend for frontend (BFF) layer for setting up the communication between front-end and back-end microservices.
  • Collaborated closely with other team members to understand product requirements and translate them into software designs and code.
Technologies: Object-oriented Design (OOD), Redux-Saga, Babel, Agile Software Development, Microservices, REST APIs, CSS, Front-end, Jest, Express.js, Apache Kafka, Zeplin, Redis, Node.js, Docker, Stylus, D3.js, Sagas, Redux, React, APIs, Full-stack, Technical Architecture

Front-end Team Lead

2014 - 2017
  • Designed and implemented a framework for building scalable front-end applications.
  • Improved the front-end development process, developed coding guidelines, and established the use of code quality tools (linting, testing).
  • Managed the front-end team, encompassing project estimation, strategic planning, and conducting code reviews.
  • Developed a web-based mobile application for students and teachers.
Technologies: Object-oriented Design (OOD), Redux-Saga, Babel, Agile Software Development, Microservices, Microsoft Visual Studio, REST APIs, .NET, Front-end, TypeScript, Jest, Express.js, C#, ASP.NET MVC, CSS, Selenium, Webpack, React, Node.js, JavaScript, Full-stack, Monorepos, SQL, Technical Architecture, Leadership

Senior Software Engineer

2011 - 2014
  • Migrated a monolithic ASP.NET application to a new service-oriented architecture built on top of the ASP.NET MVC framework.
  • Set up the platform for UI testing that could run multiple tests in parallel using Selenium, Selenium Grid, Watir, Cucumber, and Ruby.
  • Designed the architecture core services written on C# and Node.js.
  • Developed a tool for deployment in a distributed environment—it allowed the reduction of downtime during the releases and multiple deployments a day in every environment.
Technologies: Object-oriented Design (OOD), Agile Software Development, Microsoft Visual Studio, REST APIs, .NET, Cucumber, Redis, Watir, Ruby, Selenium Grid, Backbone.js, T-SQL (Transact-SQL), Entity Framework, ASP.NET MVC, Node.js, C#, APIs, Full-stack, Sass, SQL

Software Engineer

2009 - 2011
RBC Soft
  • Developed a platform for collecting and analyzing the results of the unified state exam.
  • Designed and implemented a collaboration platform that helped establish communication between various government departments.
  • Performed code reviews with peers and junior developers.
Technologies: Object-oriented Design (OOD), Microsoft Visual Studio, .NET, JavaScript, HTML, NHibernate, T-SQL (Transact-SQL), C#, ASP.NET MVC, SQL

Application for Managing Access to the SaaS Platform

An application for managing the access rights of users and groups to various company products. Even inexperienced users can configure access rights with a high level of granularity. This app was a part of a larger document management and processing platform.


A complex structured data visualization platform that allows customers to extract insights from their data. It uses various techniques to represent data through interactive graphs, diagrams, charts, and maps.

Web-based Tool for Describing Ontologies

These are applications for marking relationships in data (building an ontology) and representing these relationships in the form of a visual graph on canvas. These relationships enable the analysis of user data using machine learning algorithms.

Mobile Web Application for Teachers and Students

A web-based mobile application for teachers and students for Dnevnik.ru. It allows teachers to manage grades and homework and allows students to view their marks, homework, schedules, and updates from peers.
2003 - 2009

Master’s Degree in Applied Mathematics and Computer Science

Irkutsk State University - Irkutsk, Russia


React, Redux-Saga, Socket.IO, REST APIs, D3.js, Node.js, Selenium Grid, Entity Framework, Backbone.js, Web3.js, LitElement


Stylus, Atom, Slack, Microsoft Visual Studio, GitLab, Webpack, TeamCity, Git, GitHub, IntelliJ IDEA, PostCSS, Babel, Cucumber, Watir, Zeplin, Sketch, Lerna, Figma


Redux, .NET, ASP.NET MVC, Express.js, Jest, React Native, Next.js, Tailwind CSS, Selenium, NHibernate, UIKit, Svelte


TypeScript, CSS3, C#, JavaScript, ES7, CSS, HTML, HTML5, SCSS, GraphQL, Sass, SQL, Ruby, T-SQL (Transact-SQL), Go


Object-oriented Design (OOD), Test-driven Development (TDD), Microservices, Agile Software Development, Functional Programming, Agile Project Management, Microservices Architecture


Redis, PostgreSQL, JSON, MongoDB, Google Cloud, MySQL, Neo4j


Docker, Amazon Web Services (AWS), MacOS, Apache Kafka, Visual Studio Code (VS Code), Google Cloud Platform (GCP)


Front-end, Full-stack, Web3, APIs, Monorepos, Storyblok, Architecture, Technical Architecture, Leadership, Sagas, Storybook, Web Development, Computer Vision, Artificial Intelligence (AI), Mathematics, Cryptography, Differential Equations, Software Engineering, Applied Mathematics, Computer Science, Progressive Web Applications (PWA), MikroORM, Apollo Server, Chakra UI, Message Queues, API Gateways

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