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I’m John Ionescu, a Senior Full Stack Developer with over 12 years of experience building scalable web applications across fintech and healthcare. I specialize in designing and delivering end-to-end systems using React, TypeScript, and Node.js, backed by modern backend architectures.\n\nI excel at leading system design, delivering production-ready features, and collaborating with stakeholders in remote, client-facing environments. I’m committed to improving performance, reliability, and delivery speed while mentoring teams and ensuring clean, well-documented code.…I’m John Ionescu, a Senior Full Stack Developer with over 12 years of experience building scalable web applications across fintech and healthcare. I specialize in designing and delivering end-to-end systems using React, TypeScript, and Node.js, backed by modern backend architectures.\n\nI excel at leading system design, delivering production-ready features, and collaborating with stakeholders in remote, client-facing environments. I’m committed to improving performance, reliability, and delivery speed while mentoring teams and ensuring clean, well-documented code.

John Ionescu

Full Stack Developer, Web Developer, Front-End Developer, +2

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I’m John Ionescu, a Senior Full Stack Developer with over 12 years of experience building scalable web applications across fintech and healthcare. I specialize in designing and delivering end-to-end systems using React, TypeScript, and Node.js, backed by modern backend architectures.\n\nI excel at leading system design, delivering production-ready features, and collaborating with stakeholders in remote, client-facing environments. I’m committed to improving performance, reliability, and delivery speed while mentoring teams and ensuring clean, well-documented code.…I’m John Ionescu, a Senior Full Stack Developer with over 12 years of experience building scalable web applications across fintech and healthcare. I specialize in designing and delivering end-to-end systems using React, TypeScript, and Node.js, backed by modern backend architectures.\n\nI excel at leading system design, delivering production-ready features, and collaborating with stakeholders in remote, client-facing environments. I’m committed to improving performance, reliability, and delivery speed while mentoring teams and ensuring clean, well-documented code.

Available to hire

I’m John Ionescu, a Senior Full Stack Developer with over 12 years of experience building scalable web applications across fintech and healthcare. I specialize in designing and delivering end-to-end systems using React, TypeScript, and Node.js, backed by modern backend architectures.\n\nI excel at leading system design, delivering production-ready features, and collaborating with stakeholders in remote, client-facing environments. I’m committed to improving performance, reliability, and delivery speed while mentoring teams and ensuring clean, well-documented code.

Skills

Experience Level

Expert

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Language

English

Fluent

Work Experience

Senior Full Stack Engineer at Luxoft Romania

April 1, 2022 - Present

Designed and delivered full-stack applications using React, TypeScript, and Node.js, improving system performance by 35% across multiple projects. Led end-to-end system design for scalable applications in fintech and logistics domains, ensuring reliability and maintainability. Built and maintained RESTful APIs and backend services using NestJS, supporting high-throughput data workflows. Developed reusable frontend components and UI systems, accelerating feature delivery by 30%. Collaborated directly with clients and stakeholders to define requirements and deliver solutions aligned with business goals. Implemented CI/CD pipelines and containerized deployments using Docker and Kubernetes, improving release cycles. Optimized database queries and backend performance, reducing response times by 25%. Led code reviews and mentored engineers, ensuring high-quality and consistent code standards. Managed multiple concurrent projects, delivering features on time in remote, distributed teams.

Senior Backend Engineer at Zalando

January 1, 2019 - March 31, 2022

Developed scalable backend systems using Node.js and TypeScript for high-traffic e-commerce platforms. Contributed to frontend development using React, enhancing user experience and performance. Designed APIs and data models supporting complex business logic and integrations. Improved system performance and reliability through optimization and monitoring. Collaborated with cross-functional teams in remote environments. Supported CI/CD and cloud-based deployments. Participated in system design discussions and architecture decisions.

Full Stack Engineer at Voyager Innovations

October 1, 2014 - December 31, 2018

Built full-stack applications for financial systems using React and Node.js. Developed dashboards and reporting tools for transaction monitoring. Designed backend services and APIs supporting payment workflows. Improved UI performance and usability for customer-facing applications. Implemented asynchronous processing for backend systems. Ensured system reliability through testing and monitoring.

Software Engineer at Accenture Philippines

July 1, 2012 - September 30, 2014

Developed backend services and integrated frontend components for enterprise applications. Built RESTful APIs and managed database systems. Resolved production issues and improved system stability. Participated in full SDLC including development, testing, and deployment. Collaborated with teams to deliver scalable solutions.