Senior MERN Developer (React.js + Node.js)

<p> <strong>Headquarters:</strong> Sweden <br /><strong>URL:</strong> <a href="http://career.proxify.io">http://career.proxify.io</a> </p> <h3><strong>The Role:</strong></h3> <p>We are looking for a Senior MERN Stack Developer with heavy specialization in React.js and Node.js on behalf of one of our high-growth clients to architect, scale, and maintain high-throughput web applications. In this role, you will take operational ownership of both front-end user interfaces and back-end microservices, delivering seamless, secure, and responsive digital products. You will bridge user-facing features with complex database architectures and cloud infrastructure. You are a perfect candidate if you are growth-oriented, you love what you do, and you enjoy working on new ideas to develop exciting products</p> <p><strong> </strong></p> <h4><strong>What we are looking for:</strong></h4> <ul> <li>5+ years of professional software engineering experience designing, building, and deploying end-to-end applications using MongoDB, Express.js, React.js, and Node.js.</li> <li>Deep proficiency in modern JavaScript (ES6+), TypeScript, asynchronous programming, event loops, and memory management across client and server environments.</li> <li>Deep mastery of React internals, custom hooks, component design patterns, state management (Redux Toolkit, Zustand, or React Query), SSR/SSG frameworks (Next.js is a strong plus), and performance optimization (virtualization, code splitting, Web Vitals).</li> <li>Proven experience architecting scalable RESTful APIs, WebSockets, and/or GraphQL services. Proficiency with middleware design, authentication protocols (JWT, OAuth2, Passport.js), and event-driven architectures.</li> <li>Advanced knowledge of MongoDB schema design, aggregation pipelines, index strategy, performance tuning, and ORMs/ODMs like Mongoose or Prisma.</li> <li>Strong commitment to test-driven development using frameworks like Jest, React Testing Library, and Cypress, alongside hands-on experience with Docker, CI/CD pipelines (GitHub Actions), and AWS cloud services.</li> <li>Time zone: CET (+/- 3 hours). We are unable to consider applications from candidates in other time zones.</li> </ul> <p><strong> </strong></p> <h4><strong>Nice-to-have:</strong></h4> <ul> <li>Experience with Next.js or Remix for production-grade full-stack React frameworks.</li> <li>Familiarity with relational databases (PostgreSQL, MySQL) alongside MongoDB.</li> <li>Experience with vector databases or AI model integration into Node.js backend services.</li> <li>Exposure to micro-frontends or monorepo setups (Turborepo, Nx).</li> </ul> <p> </p> <h4><strong>Responsibilities:</strong></h4> <ul> <li>Design, develop, and deploy scalable full-stack features from initial database schema creation down to polished, pixel-perfect React interfaces.</li> <li>Build secure, high-concurrency microservices and web services, managing integrations with third-party APIs, webhooks, and real-time communication channels.</li> <li>Audit, profile, and optimize application throughput—reducing bundle sizes and rendering overhead on the front end while optimizing database queries and caching layers (Redis) on the back end.</li> <li>Lead architectural discussions, write modular and well-documented TypeScript code, enforce strict testing protocols, and conduct thorough peer code reviews.</li> <li>Collaborate with cloud and DevOps engineers to containerize applications, set up automated deployment pipelines, and maintain system monitoring tools.</li> </ul> <p><strong></strong></p> <div> </div> <h4><strong>What we offer:</strong></h4> <div> </div> <div><strong>Get paid, not played</strong></div> <div>No more unreliable clients. Enjoy on-time monthly payments with flexible withdrawal options.</div> <div> </div> <div><strong>Predictable project hours</strong></div> <div>Enjoy a harmonious work-life balance with consistent 8-hour working days with clients.</div> <div> </div> <div><strong>Flex days, so you can recharge</strong></div> <div>Enjoy up to 24 flex days off per year without losing pay, for full-time positions found through Proxify.</div> <div> </div> <div><strong>Career-accelerating positions at cutting-edge companies</strong></div> <div>Discover exclusive long-term remote positions at the world's most exciting companies.</div> <div> </div> <div><strong>Hand-picked opportunities, just for you</strong></div> <div>Skip the typical recruitment roadblocks and biases with personally matched positions.</div> <div> </div> <div><strong>One seamless process, multiple opportunities</strong></div> <div>A one-time contracting process for endless opportunities, with no extra assessments.</div> <div> </div> <div><strong>Compensation</strong></div> <div>Enjoy the same pay, every month with positions landed through Proxify.</div> <p><strong>To apply:</strong> <a href="https://weworkremotely.com/remote-jobs/proxify-ab-senior-mern-developer-react-js-node-js">https://weworkremotely.com/remote-jobs/proxify-ab-senior-mern-develope