Senior Frontend Developer

instinctools EE Labs; Remote; PLN 180,000 - 240,000; Full time

Job summary

A software development company in Poland is seeking a Senior Frontend Developer to develop and maintain React applications. The ideal candidate has over 7 years of experience with strong skills in React Hooks, TypeScript, and testing practices. This position offers flexible working hours, opportunities for learning, and a full remote work option. Applicants should have excellent problem-solving abilities and strong communication skills.

Benefits

Flexible working time

Professional team

Learning opportunities

Full remote work

Co-funding for language courses

Qualifications

• 7+ years of professional experience in Frontend development.
• Deep understanding of React hooks.
• Knowledge of state management libraries and testing principles.
• Experience with TypeScript and performance optimization techniques.
• Upper-Intermediate English proficiency.

Responsibilities

• Develop and maintain React applications using modern React Hooks.
• Manage component state and build stateless applications.
• Ensure code quality using TypeScript and write unit tests.

Skills

React Hooks

Memoization principles

State Management

TypeScript

Client-Side Rendering

Server-Side Rendering

Testing tools

Problem-solving and debugging

Communication skills

Job description

*instinctools is a software development company that provides custom software solutions for businesses of all sizes. Our team works closely with clients to understand their specific needs and provide personalized solutions that meet their business requirements.

Our team is looking for a Senior Frontend Developer for one of our clients.

Our client is the world’s first regulated digital asset bank, founded in Switzerland and Singapore, offering bank-grade services for digital assets like Bitcoin, Ethereum, and tokenized assets, including custody, trading, asset management, lending, and tokenization for institutional and private clients, bridging traditional finance with the crypto economy. They provide an integrated platform for investing in digital assets with full regulatory compliance, security, and convenience.

Tasks

• Develop and maintain React applications using modern React Hooks and best practices.
• Manage component state effectively, choosing between local and global state solutions.
• Build stateless, server-driven applications using tools like React Query.
• Apply CSR and SSR appropriately based on project requirements.
• Write and maintain unit, integration, and E2E tests using Jest, React Testing Library, and Cypress.
• Ensure type safety and code quality using TypeScript and generics.
• Contribute to scalable front-end architecture, including modular and monorepo setups (NX).

Our expectations of the ideal candidate

• 7+ years of professional experience in Frontend development.
• React Hooks: Deep understanding of React hooks, including useEffect and useLayoutEffect, their differences, and practical use cases. The candidate should know that useEffect runs after rendering, while useLayoutEffect runs before rendering, affecting visible DOM changes.
• Memoization: Knowledge of memoization principles and the ability to use React.memo, useMemo, and useCallback for performance optimization.
• Keys in React: Understanding the importance of unique keys in lists of components for proper rendering and optimization.
• State Management: Knowledge of the differences between local and global state management, experience with state management libraries like Valtio, Zustand, and an understanding of issues related to Redux (noting that Redux can be considered outdated and heavy).
• Stateless Applications: Understanding the concept of stateless applications and the ability to implement them without store libraries, such as using React Query.
• Rendering: Client‑Side Rendering (CSR) and Server‑Side Rendering (SSR): Understanding what CSR and SSR are and when each should be used depending on the project’s requirements.
• Testing: Understanding different types of testing (unit, integration, E2E) and knowledge of testing tools like Jest, React Testing Library, Cypress.
• Experience with React Testing Library, including knowledge of which methods are synchronous and which are asynchronous.
• Ability to identify and fix issues in slow‑running tests, such as analyzing components for excessive re‑renders.
• TypeScript: Type System: Experience with TypeScript, understanding the differences between any and unknown, and knowledge of generics.
• Application Architecture: Understanding architectural approaches, such as using NX for building modular project hierarchies.
• English: Upper‑Intermediate or higher
• Ability to work independently and contribute to a team environment
• Excellent problem‑solving and debugging skills
• Strong communication and collaboration skills
• Passion for building high‑quality, robust software

We offer

• flexible working time
• professional and ambitious team
• learning opportunities, seminars and conferences and time for exploring new technologies
• full remote work
• co‑funding for language courses (English)

Important Notice Regarding Your Personal Data Security

At *instinctools, we take the security of your personal data very seriously. Please be informed that all official communication, offers, and correspondence from *instinctools are conducted only through our verified company resources, including:

Important Reminder:
*instinctools will NEVER ask for sensitive personal or financial information, including:
- Bank account details
- Credit/debit card numbers
- Passwords or PINs

If you receive any suspicious requests claiming to be from *instinctools via unofficial channels (e.g., personal emails, social media DMs, or phone calls), please:

- Do not respond or share any information.

Your trust and security are our top priorities. For any questions, always verify through our official channels.

Thank you for your attention and cooperation.

We will be glad to see you in our team!