Yulian is available for hire
Hire YulianYulian Karapetkov
Verified Expert in Engineering
JavaScript Developer
Plovdiv, Bulgaria
Toptal member since October 23, 2019
Bio
Yulian is a lead software engineer with 12+ years of experience building web products, mostly in small, remote startup teams. His strongest recent experience is with React/Next.js, Svelte/SvelteKit, TypeScript, PostgreSQL, and Prisma. He combines hands-on full-stack development with technical leadership, architecture, product ownership, and delivery. Most recently, he led a team of three engineers at Peterson Academy while remaining deeply involved in development and major technical decisions.
Portfolio
Peterson Academy
React, Next.js, Svelte, SvelteKit, Firebase, Cloud Firestore...
Undisclosed Company
Svelte, Vite, Vitest, GitHub Actions, TypeScript, HTML, CSS
REAL.app, Inc.
JavaScript, Svelte, Routify, Vite, Vitest, Jest, GitHub Actions, React...
Experience
- JavaScript - 10 years
- TypeScript - 7 years
- Next.js - 5 years
- Node.js - 5 years
- React - 5 years
- Supabase - 3 years
- Svelte - 2 years
- PostgreSQL - 2 years
Work Experience
Lead Software Engineer
2023 - 2026
Peterson Academy
- Promoted from senior full-stack developer to lead software engineer in Sep 2024, taking technical leadership of a 3-developer team.
- Led 3 developers, prioritized the full engineering backlog, reviewed PRs daily, coordinated releases, and partnered with the CTO on architecture and delivery.
- Drove technical delivery through alpha and beta launches, completing critical functionality, resolving release blockers, and keeping scope focused on launch priorities.
- Led a staged data and architecture migration, redesigning all entities into relation data models and moving the product toward API-driven workflows.
- Re-architected major parts of the application, moving business logic into backend services and expanding the API substantially while keeping production running throughout.
- Owned subscription and payments architecture across Stripe, webhooks, gifting, referrals, discounts, subscription schedules, and customer pricing migrations.
- Improved release reliability by automating deployments, database migrations, versioning, GitHub release notes, and Slack release notifications.
Technologies: React, Next.js, Svelte, SvelteKit, Firebase, Cloud Firestore, Firebase Cloud Functions, Firebase Authentication, Supabase, PostgreSQL, Prisma, Tailwind CSS, Stripe, Stream Chat, Netlify, GitHub Actions
Senior Front-end Developer
2022 - 2023
Undisclosed Company
- Migrated the entire project from Routify to SvelteKit.
- Migrated unit tests from Jest to Vitest and added full unit test coverage.
- Used GitHub Actions to build the project's entire CI/CD pipeline.
Technologies: Svelte, Vite, Vitest, GitHub Actions, TypeScript, HTML, CSS
Senior Front-end Developer
2022 - 2022
REAL.app, Inc.
- Worked as a team lead as well as a core front-end developer.
- Added full unit test coverage of the project using Jest.
- Integrated payments with Tilia and Wyre and Web3 support with Ethers.js.
Technologies: JavaScript, Svelte, Routify, Vite, Vitest, Jest, GitHub Actions, React, TypeScript, HTML, CSS
Senior Front-end Developer
2020 - 2022
Playpilot
- Collaborated on developing features and maintaining the web front-end using Svelte and Sapper.
- Developed features and maintained the mobile front-end using React Native and Expo.
- Created an admin interface for managing curated movies and showed them on web and mobile platforms.
Technologies: Svelte, Sapper, React Native, Expo, Firebase, Firebase Cloud Functions, TypeScript, JavaScript, HTML, CSS
Senior Front-end Developer
2019 - 2020
Slate
- Developed from scratch an admin interface for managing resources like images, videos, and fonts.
- Designed the architecture of the front-end of the application.
- Communicated directly with the CTO of the company and lead the front-end development of the project.
Technologies: Angular, NgRx, NgRx/store, RxJS, TypeScript, HTML, CSS
Senior Full-stack Developer
2018 - 2019
Pikkop
- Developed the customer wallet, integrating multiple third-party providers, using Angular, Cloud Firestore, and Firebase Cloud Functions.
- Created the admin panel of the shipping platform, public page for the user shipments, and the shipment creation flow.
- Built, supported, and debugged many of the features in the shipping platform.
Technologies: Angular Material, NgRx, Express.js, Node.js, Firebase Cloud Functions, Cloud Firestore, Firebase, Angular
Senior Full-stack Developer
2017 - 2018
GameLeap
- Created the front-end of a course preview page, including a custom video player with playlists, built with JW Player and Angular.
- Developed the front-end for the referral program using Angular.
- Supported and debugged the core features of the game learning platform.
Technologies: Mongoose, MongoDB, Express.js, Node.js, Angular
Senior Full-stack Developer
2015 - 2017
Klear Lending
- Developed a budget management web app using ASP.NET Web API, MS SQL Server, Entity Framework, and AngularJS.
- Created a CMS using ASP.NET MVC, MS SQL Server, and Entity Framework.
- Designed several calculators created to facilitate the customer in making the best decision when applying for a loan. Used ASP.NET Web API and MVC and AngularJS.
- Built the front-end of the investor self-service system in the P2P lending platform, including the primary and secondary markets and customer wallets, using AngularJS.
- Created the landing pages of the platform and a referral program system.
- Implemented responsive design supporting multiple resolutions and all major browsers, including Internet Explorer 9.
- Supported and debugged the modules of the P2P lending platform.
Technologies: AngularJS, jQuery, JavaScript, Entity Framework, Microsoft SQL Server, .NET Core, Web API, ASP.NET MVC
Full-stack Developer
2013 - 2014
BankSoft
- Created a car insurance application form using OCR technology, along with ASP.NET MVC, jQuery, PL/SQL, and Oracle.
- Developed an amortized loan module for an internal system, serving the banking and financial industry, using ASP.NET WebForms, jQuery, PL/SQL, and Oracle.
- Supported the main products of the company, using ASP.NET WebForms and MVC, WCF, Classic ASP, JavaScript, jQuery, PL/SQL, and Oracle.
Technologies: Oracle, PL/SQL, jQuery, JavaScript, Classic ASP, Windows Communication Foundation (WCF), Model View Controller (MVC), ASP.NET Web Forms
Project History
GitHub Viewer
An example project written in Angular and Firebase, showing a list of mock GitHub repositories that the logged-in user can choose as favorite/unfavorite and preview.
Code: https://github.com/yuliankarapetkov/github-viewer
Code: https://github.com/yuliankarapetkov/github-viewer
Rentals
https://github.com/yuliankarapetkov/rentalsSample full-stack project for apartment rentals built with Angular, NgRx/store, RxJS, NestJS, PostgreSQL, Angular Material, TypeScript, HTML and CSS.
Code: https://github.com/yuliankarapetkov/rentals
Code: https://github.com/yuliankarapetkov/rentals
Todo App With React
Sample todo app built with React, TypeScript, Redux Toolkit, Redux-observable, RxJS, Firebase, HTML, and CSS.
Demo: https://todo-react-bb577.web.app/
Code: https://github.com/yuliankarapetkov/todo-react
Demo: https://todo-react-bb577.web.app/
Code: https://github.com/yuliankarapetkov/todo-react
Todo App With Angular
Sample todo app built with Angular, NgRx/store, RxJS, TypeScript, Firebase, Cloud Firestore, Firebase Cloud Functions, HTML, and CSS.
Demo: https://sample-angular-todo-app.web.app/
Code: https://github.com/yuliankarapetkov/todo-app
Demo: https://sample-angular-todo-app.web.app/
Code: https://github.com/yuliankarapetkov/todo-app
Education
2010 - 2014
Bachelor of Engineering Degree in Computer Systems and Technologies
Technical University Sofia - Sofia, Bulgaria
Skills
Libraries/APIs
Node.js, React, Entity Framework, jQuery, Web API, NgRx, NgRx/store, RxJS, Stripe
Tools
Git, SourceTree, Slack, Mongoose, Expo, Vitest, Firebase Authentication, Prisma, Stream Chat
Languages
JavaScript, TypeScript, C#, SQL, Python, HTML, CSS
Frameworks
Angular, Ionic 4, NestJS, Svelte, Sapper, Next.js, .NET Core, Express.js, AngularJS, React Native, Bootstrap, ASP.NET Web Forms, Classic ASP, ASP.NET MVC, Angular Material, Redux, Jest, Tailwind CSS
Platforms
Firebase, Windows, Oracle, MacOS, Visual Studio Code (VS Code), Netlify
Storage
Cloud Firestore, MongoDB, PostgreSQL, Microsoft SQL Server, Oracle SQL, PL/SQL
Paradigms
Model View Controller (MVC)
Other
Firebase Cloud Functions, Supabase, TypeORM, Windows Communication Foundation (WCF), Redux-observable, Routify, Vite, GitHub Actions, SvelteKit, Cursor AI, Linear
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