Frontend Staff Engineer
KoinlyLondon, United Kingdom
80000USD - 100000USDReactTypescriptAPIsData AnalysisDocker
We're looking for a Frontend Staff Engineer to take deep ownership of our data platform - the engine behind products at the intersection of crypto, finance, and tax. You'll work across a modern React web application and a high-performance distributed data-processing backend, with a new React Native mobile app joining your scope in the future.
This is a senior, hands-on role for someone who combines exceptional engineering craft with genuine product ownership. We expect you to lead by example: writing high-quality code, making sound architectural decisions, and raising the bar for the entire frontend team.
Responsibilities
- Own frontend features end-to-end ensuring a high-performance experience for complex crypto tax data.
- Focus on optimizing, refactoring, and elevating our existing codebase while steadily delivering critical new features for a high-performance interface that handles massive datasets and complex DeFi reconciliations.
- Work closely with product and design, serving as the primary frontend partner for Product. Evaluate ideas from a technical perspective, propose creative solutions, and take real ownership of our frontend strategy.
Requirements
- Deep understanding of modern, complex web application architecture and the design patterns that support it at scale.
- Strong attention to detail and advanced frontend styling skills, including reliable cross-browser behavior and pixel-level precision.
- Fluency with the latest AI development tools such as Claude/Codex/Cursor, and the judgment to use them effectively in a professional workflow.
- Deep, production-level experience with React 19 with the React Compiler, in strict, modern TypeScript.
- Expert-level TypeScript skills, reaching for strong typing instinctively, not as an afterthought.
- Deep React experience, including understanding of React's internals, performance optimization, and modern tooling.
- Experience with the TanStack ecosystem - Router, Query, and Table.
- Experience with Radix UI and Mantine for components.
- Experience with Tailwind CSS v4 (with class-variance-authority and tailwind-merge).
- Experience with Vite + Vitest (unit and browser/Playwright), Storybook with Chromatic for visual regression.
- Experience with Highcharts for data visualization and Sentry for error monitoring.
- Experience with Bun runtime with modern TS tooling (oxlint, Biome).
- Experience with data parsing and wrangling: csv-parse, xlsx (SheetJS), node-html-parser.
- Experience with blockchain libraries.
- Experience with RabbitMQ and Redis (ioredis).
- Experience with PostgreSQL, Heroku, GitHub, JIRA.
- Experience building mobile applications with React Native is nice to have.
- Public portfolio of projects available on GitHub or similar platforms is nice to have.
- Background working on financial products is nice to have.
- Hands-on experience with blockchain and crypto technologies is nice to have.
- Familiarity with Ruby (our services interoperate with a Ruby codebase) is nice to have.
- Understanding of DeFi protocols and how they work on-chain is nice to have.