Stepan is currently unavailable
Stepan Kasyanenko
Verified Expert in Engineering
Front-end Developer
Stuttgart, Baden-Württemberg, Germany
Toptal member since March 30, 2026
Bio
Stepan is a senior front-end developer with over 15 years of experience designing and implementing scalable, high-performance web architectures. His extensive experience spans fintech, healthtech, and eCommerce sectors. Currently based in Germany, Stepan specializes in the Angular ecosystem and TypeScript.
Portfolio
Celonis
Angular, TypeScript, CSS3, Playwright, Cypress, RxJS, NgRx, MacOS, WebStorm...
Climedo
Angular, TypeScript, HTML5, CSS3, RxJS, NgRx, REST, MacOS, WebStorm, Git...
Online Freelance Agency
Angular, TypeScript, CSS3, Windows, WebStorm, Git, Chrome DevTools...
Experience
- CSS3 - 15 years
- HTML5 - 15 years
- TypeScript - 7 years
- Angular - 7 years
- Algorithms - 6 years
- RxJS - 5 years
- NgRx - 5 years
- Playwright - 3 years
Preferred Environment
MacOS, Windows, WebStorm, Cursor AI, Git, Chrome DevTools
The most amazing...
...achievement has been optimizing complex dashboards to achieve 40% performance gains.
Work Experience
Senior Front-end Engineer
2022 - PRESENT
Celonis
- Built the web component of the core features for the views system, enabling the creation of comprehensive dashboards.
- Mentored junior developers, providing technical guidance and support.
- Enhanced the quality of the product by creating end-to-end tests on critical user journeys and automated regression tests.
Technologies: Angular, TypeScript, CSS3, Playwright, Cypress, RxJS, NgRx, MacOS, WebStorm, Git, Chrome DevTools, Data Structures, Algorithms, Computer Science, JavaScript, HTML5, REST
Senior Front-end Engineer
2021 - 2022
Climedo
- Developed core features for a clinical trial system that collects medical data from patients and supports the execution of clinical trials.
- Architected the granular permission control for the clinical trial system.
- Optimized the performance of clinical trial pages with over 150 form inputs by refactoring the NgRx state management.
Technologies: Angular, TypeScript, HTML5, CSS3, RxJS, NgRx, REST, MacOS, WebStorm, Git, Chrome DevTools, Data Structures, JavaScript
Lead UI/UX Developer
2018 - 2021
Online Freelance Agency
- Developed new features for the Conform5 health care system, enabling the collection of clinical trial data.
- Optimized the performance of a PDF annotation system by applying caching and lazy loading principles.
- Directed the technical implementation of the web component of a medical data repository system.
Technologies: Angular, TypeScript, CSS3, Windows, WebStorm, Git, Chrome DevTools, Data Structures, Algorithms, Computer Science, JavaScript, HTML5, REST
Front-end Developer
2017 - 2018
Creatium
- Developed new building blocks to enhance the functionality of the no-code platform.
- Improved the real-time performance of the no-code platform to 30% by utilizing Virtual DOM (VDOM) capabilities.
- Spearheaded the technical refactoring of the no-code system, decreasing the bundle size by 80%.
Technologies: JavaScript, HTML5, CSS3, Windows, Git, Chrome DevTools, Data Structures, REST
Senior Full-stack Developer
2010 - 2017
Central Bank of Uzbekistan
- Built a credit bureau system to collect credit data from commercial banks and financial institutions, enabling the generation of credit scores and reports.
- Architected the web component of the national payment system, a gateway processing payments from individuals to businesses, handling one million transactions daily nationwide.
- Engineered the web component of the Central Bank of Uzbekistan system, enabling the digitalization of key banking processes.
- Developed a payment desktop application that is used to create, submit, and monitor payments to the Central Bank by legal entities.
Technologies: Oracle PL/SQL, C#, JavaScript, HTML5, CSS3, Windows, Git, Data Structures, Algorithms, Computer Science, REST
Experience
Celonis Views
https://www.celonis.com/I worked as a senior Angular developer on the page in the Celonis System Web Application, creating new features, fixing bugs, improving quality, and adding end-to-end tests. That page allows users to build comprehensive dashboards with data and custom actions.
Education
2006 - 2010
Bachelor's Degree in Informatics and Applied Mathematics
National University of Uzbekistan - Tashkent, Uzbekistan
Skills
Libraries/APIs
RxJS, NgRx, Playwright
Tools
WebStorm, Git, Nx
Languages
JavaScript, HTML5, CSS3, TypeScript, C#
Frameworks
Angular, Cypress
Paradigms
REST
Platforms
MacOS, Windows
Storage
Oracle PL/SQL
Other
Chrome DevTools, Data Structures, Algorithms, Computer Science, Cursor AI
Collaboration That Works
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
1
Share your needs
Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2
Choose your talent
Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3
Start your risk-free talent trial
Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.
Top talent is in high demand.
Start hiring