Sebastian Mach

Software Engineer

Personio

Jun 2025 - Current (1 year 4 months)

Enterprise HR platform enhancing payroll and workforce automation for large-scale European customers using cloud-native microservices and data-intensive workflows.
• Designed and delivered TypeScript and Node.js microservices on AWS Lambda and API Gateway, improving system scalability for enterprise HR workflows.
• Built responsive React interfaces for HR dashboards, reducing load time and improving user interaction performance across large enterprise customer deployments.
• Optimized PostgreSQL and Redis data layers, reducing query latency and improving high-volume payroll processing efficiency by 25% systems.
• Implemented CI/CD pipelines and automated testing for Node.js services, increasing deployment reliability and

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Full Stack Engineer

itCraft

Oct 2022 - May 2025 (2 years 8 months)

Built custom full-stack applications for European clients in fintech and logistics using React, Node.js, Django and cloud services.
• Led architecture of full-stack applications using React, Node.js, and Django, delivering scalable APIs for fintech and logistics clients.
• Developed AWS-based microservices using Lambda and API Gateway, improving backend processing efficiency and reducing service downtime by 20%.
• Built React-driven user interfaces with TypeScript, improving usability and reducing customer support tickets across enterprise SaaS platforms.
• Optimized PostgreSQL queries and Redis caching strategies, increasing API throughput and improving system response times significantly in production.
• Improved

Full Stack Engineer

Zalando

Mar 2020 - Sep 2022 (2 years 7 months)

Contributed to large-scale e-commerce product engineering and backend services supporting high-traffic fashion marketplace platforms.
• Developed React components for high-traffic ecommerce features, improving page rendering performance and user engagement across European markets platforms.
• Built Node.js REST APIs powering product catalog services, supporting scalable backend operations for millions of daily users traffic.
• Optimized PostgreSQL schema design and indexing strategies, reducing query latency and improving checkout performance across platform systems reliably.
• Implemented AWS cloud infrastructure for services using S3 and EC2, enhancing deployment stability and release automation processes workflow.

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Junior Software Engineer

Skylab

Jul 2018 - Feb 2020 (1 year 8 months)

Supported early-stage software development projects focusing on web applications and internal tools with mentorship from senior engineers.
• Assisted in building JavaScript web applications and internal tools, contributing to frontend features and backend integration tasks teams.
• Implemented HTML, CSS, and JavaScript UI components, improving usability and maintaining consistent design system standards across platforms teams.
• Supported Node.js backend services, fixing bugs and improving API stability under senior engineer supervision in production systems environments.
• Worked with PostgreSQL databases, assisting with query optimization and data validation tasks in development environments agile teams cycles.
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Sebastian Mach

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