/Senior Frontend Engineer (React)

Senior Frontend Engineer (React)

PolandRemoteplvia direct
// Job Type
Full Time
// Salary
Not disclosed
// Posted
3 weeks ago
// Work Mode
remote

About the Role

Our client is looking for a Senior Frontend Engineer to build and maintain a new educational assistant product, automate end-to-end flows with Playwright, and develop the UI platform that powers the user experience.

What You'll Do:

  • Build and maintain the frontend layer for a new product inside an existing platform.
  • Work on the UI platform: shared components, patterns, and internal tooling to ship faster and keep UX consistent.
  • Build responsive chat experiences with both text and voice modes.
  • Design and optimise high-frequency real-time React state for smooth text streaming and interruptible two-way voice communication with LLMs.
  • Work with forms, dropdowns, charts, file uploads with graceful fallbacks.
  • Improve reliability and performance, optimise rendering and user flows.
  • Own technical decisions for frontend architecture.
  • Collaborate closely with product managers, designers, and backend engineers to deliver impactful features.
  • Develop Component and unit tests and Playwright E2E tests that validate main business flows, catch regressions early, and keep the product reliable.
  • Own features end-to-end: implementation, testing, monitoring signals (errors, user-reported issues), and continuous improvements.
  • Help establish engineering best practices, code quality standards, and technical documentation as the team scales.
  • 6+ years of commercial experience in Frontend development.
  • Proficiency in modern React JS.
  • Proficiency in TypeScript.
  • Experience with agentic assistants and their typical UX patterns.
  • Form handling with React Hook Form + schema validation (e.g. Zod).
  • Charting/data visualisation (Recharts, visx, D3, or similar).
  • Experience with a server-state/data-fetching library (TanStack Query / React Query, SWR, or RTK Query): caching, invalidation, polling, and optimistic updates.
  • Strong CSS fundamentals: responsive layout (flexbox/grid), CSS custom properties, and a styling system (CSS Modules, Tailwind, or CSS-in-JS), as well as cross-browser behaviour.
  • Proven expertise in real-time React state for streaming AI: token streaming (SSE / fetch streams) and low-latency, interruptible bidirectional voice using WebRTC and/or WebSockets, the Web Audio API (AudioWorklet, media capture), and voice-activity/barge-in handling.
  • Hands-on experience with browser audio: getUserMedia, Web Audio / AudioWorklet, echo cancellation, voice-activity detection, and barge-in/interruption (cancelling in-flight TTS when the user starts speaking).
  • Ability to write maintainable architecture: clear abstractions, shared UI platform components, and good engineering hygiene.
  • Strong focus on security and data privacy (PII handling, tokens, safe storage practices).
  • Strong ownership: ability to do independent research, solve problems, and unblock yourself autonomously.
  • Accessibility for conversational UIs: live-region streaming, captions/transcripts for voice, keyboard and screen-reader support.
  • Knowledge of observability for frontend: Sentry, logging, analytics events, debugging production issues.
  • Startup experience where autonomy, ownership, and speed matter.
  • Knowledge of CI/CD pipelines and containerisation with Docker.
  • Expertise with subscription-based or B2B/B2C SaaS businesses.
  • Market salary.
  • 20 workdays/year paid vacation.
  • Full-time remote work with flexible working hours.
  • Fast-paced, product-driven environment with real ownership and autonomy.
  • Opportunity to shape architecture and tech stack in a VC-backed startup from the early stages.
  • Close collaboration with a strong product team (PM, Design, Growth).
  • A culture of transparency, minimal bureaucracy, and quick decision-making.
  • Smart, ambitious teammates who value impact over process.

We look forward to receiving your CV and learning more about your experience!

Dear Candidates, due to a high volume of applications, only selected candidates will be contacted for interviews. We appreciate your understanding. Thank you for considering a career with us.

  • Work type
  • Full-time
  • Location
  • Remote

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