Senior Frontend Engineer

Senior Frontend Engineer

ZirconTree is changing the way media agencies and marketing teams work with real-time bidding (RTB). Our SaaS system connects global platforms into one intuitive solution that enables efficient campaign launch and AI-generated media planning. We offer both self-service and managed-service models for agencies and brands alike.

SK/CZ + Global Opportunities

Bratislava/Prague (Hybrid or Remote)

Work Location

Senior

Seniority level

Full-time, freelance

Employment type

Role overview

We are looking for an experienced Senior Frontend Engineer to design and build modern, scalable user interfaces. We require strong knowledge of JavaScript/TypeScript, modern frontend frameworks (e.g. React), and the ability to take technical ownership while collaborating closely with product and backend teams.

Your work will directly impact products used daily by our clients – tools that accelerate marketing workflows and turn data into real value.

If you enjoy challenges and like balancing elegant solutions with high performance, keep reading. 👇

Your mission: Your goal will be to take our frontend to the next level. This includes:

Unifying frontend architecture (feature-sliced design, shared UI kit). Performance optimization: memoization, code splitting, virtualization, RTK cache & invalidation.

Secure and type-safe APIs, Zod (request/response validation), error normalization. Accessibility by default: semantics, focus management, A11y standards.

CI pipelines: type checks, linting, tests, builds, bundle-size guards, previews. Mentoring, code reviews, and setting standards (handbook, PR checklist).

What we expect from you

Ideally 5+ years of experience with React + TypeScript (strict), complex forms, state management.

Redux Toolkit + RTK Query (tags, caching, retries, optimistic updates).

Zod/Joi, designing frontend–backend contracts.

UI libraries (Chakra/Headless UI/Radix), theming, accessibility.

Vite/Webpack, bundle analysis, dynamic imports.

Testing: unit & component tests (Testing Library), e2e tests (Playwright).

Profiling (React Profiler, Web Vitals) and eliminating unnecessary re-renders.

Nice to have: i18n (react-i18next), feature flags (Unleash / ConfigCat).

Our mindset

Transparency, trust, and open communication.

Focus on results, efficiency, and quality.

Initiative, ownership, and a growth mindset.

Collaboration, mutual support, and team spirit.

Continuous improvement and curiosity.

We at Zircon Tree believe that the way we work is just as important as the result. Therefore, we expect all team members to share and develop these values.

Benefits

Remote work and flexible working hours

Original offices and a friendly atmosphere

Dynamic environment of a fast-growing innovative company

Multisport card and sick days

Career development, training courses, workshops, and conferences

Team buildings, positive energy, and a real work–life balance

How to let us know you're interested

Send us your CV and a short cover letter (or a 2-minute video) to careers@zircontree.com and include your consent for personal data processing.

Consent for Personal Data Processing:

I hereby give my consent to ZirconTree s.r.o. to process my personal data provided in my CV and cover letter for the purposes of participating in the selection process and maintaining record of applicants, in accordance with Act No. 18/2018 Coll. on Personal Data Protection and GDPR. This consent is granted for a period of 12 months and may be withdrawn at any time in writing.