Looking for a job

Sergei Karasev

@sergeikarasev

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I build resilient React fintech and blockchain product interfaces.

Armenia

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What I'm looking for

I'm looking for hands-on frontend work on product teams building reliable, data-heavy user experiences, especially where transaction flows, provider failures, shared UI systems, and production performance matter.

I've built data-heavy fintech and blockchain interfaces at SingularityFinance, including a multi-asset portfolio dashboard, Ethereum and BNB Chain staking, and a tiered KYC participation product. I delivered five-plus partner projects while maintaining a live product platform holding up to $50M in user deposits at peak.

I work hands-on across React, TypeScript, Next.js, shared component libraries, and Nx monorepos. I’ve led live migrations to Next.js 15, React 19, wagmi v2, and React Query v5, enabled TypeScript strict mode while resolving 800+ errors, reduced build time from 45 to 12 minutes, and cut production bundle size by 50%.

I focus on failure paths that matter to users: slow providers, stale data, race conditions, stuck transactions, and expensive rendering under load. I’ve also led frontend teams at Science Guide and SuperJob, and continue to bring code review, mentoring, CI, release, and rollback experience to hands-on product work.

Experience

Work history, roles, and key accomplishments

Senior Frontend Engineer

SingularityFinance

Dec 2023 - Jul 2026 (2 years 7 months)

Built three main product areas in an Nx monorepo of Next.js/React/TypeScript apps, including a multi-asset portfolio dashboard, staking product, and tiered participation product. Led migrations on a live codebase, reduced build time from 45 to 12 minutes, and cut production bundle size by 50%.

React Redux React Query Next.js Blockchain Ethereum AWS

Harmony - Frontend Engineer (Web3)

Harmony

May 2021 - Dec 2023 (2 years 7 months)

Built and maintained product frontends for cross-chain bridges and
ecosystem dApps.

- Ethereum - Harmony Bridge: primary frontend for the cross-chain bridge
between Ethereum, BSC, Harmony.
https://github.com/harmony-one/ethhmy-bridge.frontend

- Bitcoin bridge: frontend for cross-chain BTC transfers into the Harmony
ecosystem.

Science Guide - Frontend Team Lead

Science Guide

Sep 2019 - May 2021 (1 year 8 months)

- Led a team of 5 frontend engineers. Hiring, code review, sprint
planning, and delivery for the main product.

Frontend Team Lead

Science Guide

May 2014 - Sep 2019 (5 years 4 months)

One of the largest job platforms in Russia, 1M+ daily active users. Joined during a full product rewrite, promoted to Team Lead.

- Rewrote the product from scratch with the team: a new frontend stack (React + Redux) and a new API designed in parallel.

PostgreSQL React Redis Redux Material UI