Frontend Developer - Freelancer

Lingaro; Polska; On-site; PLN 180,000 - 240,000; Full time

Job summary

Lever, Inc. is seeking a senior Front-end Engineer to design, build, and optimize React/Next.js applications. You will collaborate with BA, QA, and offshore teams to deliver high-performance web experiences.

You should have 5+ years, strong JS/TS, and cloud experience (GCP preferred). The role emphasizes scalable UI, testing, accessibility, and using AI-assisted tools to improve productivity while maintaining quality.

Qualifications

• 5+ years of professional experience.
• Excellent communication skills.
• Strong ownership and proactive approach.
• Strong experience in JavaScript and TypeScript.
• Thorough understanding of React/Next.js core principles, React Router, hooks, Redux, and web performance.
• Developing and maintaining modern distributed microservices.
• Cloud environments (Google Cloud Platform preferred).
• Building, testing, and troubleshooting high-volume web services using REST & JSON.
• Solid data structures and algorithms in JS.
• Semantic HTML expertise.
• CSS expertise with Tailwind, Styled Components, CSS Modules, and SASS.
• Browser-based debugging tools.
• Responsive and adaptive design.
• Experience with testing (Unit testing, react-testing-library, E2E).
• Experience using AI-assisted development tools (Claude, GitHub Copilot, etc.).
• Ability to apply AI tools for coding, debugging, testing, refactoring, and documentation.
• English (B2+).

Responsibilities

• Design, build and maintain efficient, reusable, and reliable code.
• Build React/Next.js based applications.
• Ensure the best possible performance, quality, and responsiveness of applications.
• Identify bottlenecks and bugs, and devise solutions.
• Help maintain code quality.
• Participate in agile team scrums and communicate status, roadblocks, and timelines.
• Collaborate with BA, QA, developers and offshore teams for planning, design, development, testing, and maintenance of web and mobile web apps.
• Share knowledge with the team during workshops.

Skills

JavaScript

TypeScript

React

Next.js

Web performance

Security

Semantic HTML

CSS (Tailwind, Styled Components, CSS)

Testing (Unit, react-testing-library,

AI-assisted development tools

English (B2+)

Tools

Docker

Contentful

NodeJS

GraphQL

GitHub Copilot

Job description

Growth through diversity, equity, and inclusion. As an ethical business, we do what is right — including ensuring equal opportunities and fostering a safe, respectful workplace for each of us. We believe diversity fuels both personal and business growth. We're committed to building an inclusive community where all our people thrive regardless of their backgrounds, identities, or other personal characteristics.

Tasks

• Design, build and maintain efficient, reusable and reliable code.
• Build React/Next.js based applications.
• Ensure the best possible performance, quality, and responsiveness of applications.
• Identify bottlenecks and bugs, and devise solutions to mitigate and address these issues.
• Help maintain code quality.
• Participate in the agile team scrums and effectively communicate to the team the status, roadblocks, and timelines for the task at hand.
• Must be able to collaborate with BA, QA, developers and offshore developers to plan, design, develop, test, and maintain mobile web and desktop-based applications requested by the stakeholders.
• Share knowledge with the team during workshops.

Requirements

What We're Looking For:

• 5+ years of professional experience.
• Excellent communication skills.
• Great ownership of assigned tasks. Self-driven and proactive approach.
• Strong experience in JavaScript and TypeScript.
• Thorough understanding of React/Next.js core principles along with React router, hooks, Redux (or the like) workflows, Web performance and security.
• Developing and maintaining modern distributed micro services.
• Development in Cloud environments (Google Cloud Platform preferred).
• Building, testing, and troubleshooting high volume web services using API Protocols and Data Formats (REST & JSON).
• Solid foundation in data structures, algorithms and its implementation in JS.
• Expertise with semantic HTML.
• Proficiency in CSS, including Tailwind, Styled Components, CSS Modules, and SASS.
• Expertise browser-based debugging tools.
• Experience with responsive and adaptive design.
• experience with Testing (Unit Testing, react-testing-library, E2E).
• Keen understanding of web application development process and standard methodologies.
• Experience using AI-assisted development tools to improve productivity and code quality, such as Claude, GitHub Copilot, and similar tools.
• Ability to apply AI tools effectively for coding, debugging, testing, refactoring, and documentation while maintaining high standards of code quality, security, and best practices.
• English (B2+).

What Will Set You Apart:

• Previous experience in Front-end development with Docker.
• Experience with Headless CMS (preferably Contentful).
• Experience with NodeJS.
• Knowledge of GraphQL.

Missing one or two of these qualifications? We still want to hear from you! If you bring a positive mindset, we'll provide an environment where you feel valued and empowered to learn and grow.