Лев

Lev Saltsyn
Frontend Engineer | React, TypeScript, Next.js | Web3
& AI Integrations

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SUMMARY

● Frontend Engineer with 5+ years of experience building product platforms, scalable web
applications, and user-facing features across startups and technology companies.
● Strong expertise in React, TypeScript, Next.js, frontend architecture, API integrations, and
performance optimization. Experienced in owning features end-to-end, collaborating closely with
product and design teams, and delivering production-ready solutions.
● Additional experience with Web3 products, blockchain integrations, and AI-assisted
engineering workflows enables me to quickly adapt to complex technical domains and build
integration-heavy products.

● English: B2+


SELECTED HIGHLIGHTS

● 5+ years of commercial software engineering experience.
● Built products from concept to production.
● Strong expertise in React, TypeScript and modern frontend architecture.
● Experience building Web3 and integration-heavy applications.
● Multi-chain deployment experience across Ethereum, Base, Polygon and Arbitrum.
● Startup and product-oriented engineering mindset.

TECHNICAL SKILLS

● Frontend Technologies: TypeScript (strict mode), JavaScript (ES2023+), React (Hooks,
Context, Suspense), Redux/MobX, React Query, Next.js (App Router, Server Components,
SSR, SSG, ISR), TanStack Query, Zustand, JSX/TSX, HTML5, CSS3, SCSS/SASS, Tailwind
CSS, BEM, Responsive Design, Accessibility (a11y), Cross-browser compatibility, i18n
● Next.js: App Router, Pages Router, Server-Side Rendering (SSR), Static Generation (SSG),
Client/Server Components, Routing, API integration, Performance optimization
● API & Data: REST API integration, client-server communication, JSON, async data handling,

error handling, form flows
● Build & Dev Tools: Git, GitHub, GitHub Actions , GitLab, Bitbucket, CircleCI, CI/CD pipelines,
npm, yarn, Webpack, Rollup.js, Babel, Vercel
● Testing: Jest, React Testing Library, Playwright, Hardhat, Truffle, Mocha, Chai (Unit &
integration testing)
● Product Delivery: Figma (design handoff), Jira, Confluence, Agile / Scrum, Task
decomposition, Effort estimation, Feature delivery lifecycle, Refactoring, Bug fixing,
Dependency management
● Additional: Node.js, Web3.js, Ethers.js, Wallet Integrations, Solidity, DeFi Protocols, Docker,
● AI & Developer Productivity: Claude Code, Cursor, GitHub Copilot, GPT-based development
workflows, AI-assisted debugging and refactoring, Code and test generation workflows
● Familiar with: React Hook Form

PROFESSIONAL EXPERIENCE


Development of financial software. «Finline»

Frontend Engineer / Full-Stack Engineer
02/2023 – 04/2026
Project: Competitive gaming platform with Web3 integrations

Technologies: React.js, Next.js, TypeScript, Wagmi, REST APIs, Jest, React Testing Library, Solidity,
Hardhat, Ethers.js, Chai, Truffle, web3.js, Walletconnect, Jira, GitHub

Responsibilities & Achievements:

- Developed and maintained user-facing features using React, TypeScript and Next.js.
- Built reusable and scalable UI components and application flows.
- Integrated REST APIs, wallet connectivity and blockchain interactions into the frontend application.
- Refactored legacy code and improved maintainability and development standards.
- Collaborated closely with product stakeholders, designers and engineers to deliver
production-ready features.
- mentored 3 engineers
- Participated in architecture decisions and owned features from concept to production.
- Designed and implemented smart contract architecture supporting the platform ecosystem.
- Deployed and maintained blockchain infrastructure across Ethereum, Base, Polygon and Arbitrum
- Owned features end-to-end from requirements clarification to production release.


«Distributed lab»

Frontend Engineer / Full-Stack Engineer
06/2022 – 01/2023
Project: Web application platform with interactive user flows

Technologies: React.js, Next.js, TypeScript, JavaScript, REST APIs, Jest, React Testing Library, Solidity,
ERC20, web3.js, Hardhat, Mocha, Truffle, Figma, SCSS, HTML, BitBucket, Jira

Responsibilities:

- Built and delivered frontend features using React and TypeScript.
- Developed reusable UI components based on Figma designs.
- Integrated APIs and implemented client-side business logic.
- Designed and built frontend architecture for a Web3 application.
- Developed smart contracts and wallet integrations supporting product functionality.

«Vanilline»

Frontend Developer
04/2022 – 05/2022
Project: E-commerce website

Technologies: React.js, Next.js, JavaScript, SCSS, HTML5, CSS3, Vercel, EmailJS, Jira, Figma

Responsibilities:

- Designed front-end architecture and component structure
- Implemented responsive UI based on approved designs
- Integrated external services and client communication flows
- Managed repositories, deployment setup, and release preparation
- Ensured cross-browser and mobile compatibility
- Supported feature updates and front-end improvements

Mobiform

Front-End Developer
10/2020 – 03/2022
Project: Online platform with e-commerce and 3D kitchen editor

Technologies: TypeScript, Stencil.js, Ionic, JavaScript, Firebase (Firestore, Cloud Functions),
Rollup.js, x3dom, HTML5, SCSS

Responsibilities:

- Developed a 3D kitchen editor using x3dom
- Built CRM functionality for customer management
- Converted designs into scalable TSX components
- Applied OOP principles in component and service design
- Ensured performance optimization and cross-platform compatibility
- Worked on feature enhancement and ongoing front-end improvements

Momo (陌陌)

Front-End Developer
01/2020 – 10/2020
Project: Social platform with chat and video communication

Technologies: React.js, Redux, Node.js, JavaScript, REST APIs, Webpack, SASS, HTML5,
CSS3

Responsibilities:

- Built the platform from scratch, including UI and client-side logic
- Integrated state management using Redux
- Implemented API interactions and JSON-based data flows
- Refactored and modernized legacy code.
- Delivered responsive, cross-browser compatible functionality
- Participated in feature delivery and codebase modernization

EDUCATION

● React.js for Web Development — IT School
of Professional Programming
● Frontend Development (JavaScript + React)
— Thinknetica
● Basics of Web UI Development —
Prometheus / Lviv IT School
● Aviation Computer Systems Engineer —
National University “Kyiv Aviation Institute"