Patryk – React, Java, Spring

The leading German platform for real estate listings, catering to sales and rentals. It offers multiple viewing options, accommodating private buyers, sellers, and professional real estate brokers. Features include detailed listings display, search, and complex filter options.

• Was a vital member of the core search engine API team, specializing in maps and pricing;
• Maintained and optimized search engine performance, ensuring responses within milliseconds;
• Led the design and implementation of RESTful APIs;
• Conducted A/B testing utilizing feature toggles and Optimizely;
• Directed the integration of new microservices hosted on AWS subdomains;
• Implemented dynamic map interfaces on top of Google Maps and new frontend components for Maps Library;
• Migrated servers and clients to OAuth2 for M2M communication;
• Designed and integrated AI content generation using Jenkins multipipeline jobs, bash processing scripts, AWS Lambda, and S3;
• Upgraded and modernized React libraries to version 18;
• Defined and monitored metrics and performance dashboards using Datadog;
• Conducted unit tests, E2E, and integration tests.

Europe's largest online marketplace for vehicles, facilitating millions of transactions with over 30 million active users per month. This platform provides a comprehensive and user-friendly interface for buying and selling cars, offering advanced search features, real-time data updates, and seamless integration with various automotive services.

• Revamped the private seller section, driving increased sales through UI/UX enhancements, leading to improved user engagement and higher conversion rates;
• Worked on the design and implementation of RESTful APIs, leveraging AWS, Java, and Scala for integrating multiple microservices, streamlining data retrieval and preparation for users;
• Developed and maintained scalable backend solutions using Java Spring and Scala, ensuring high performance and reliability in the marketplace;
• Built and optimized the front end using React and TypeScript, enhancing the overall user experience and interface responsiveness;
• Utilized Node.js for server-side scripting and efficient handling of asynchronous operations;
• Managed data storage and retrieval using PostgreSQL, ensuring data integrity and high availability;
• Integrated AWS services for cloud infrastructure, including EKS, S3, and API Gateway, to achieve scalable and resilient system architecture;
• Developed monitoring and logging solutions to maintain system health and performance - DataDog.

A comprehensive online customer service software that offers real-time chat help desk functionalities and advanced web analytics capabilities to enhance customer support and engagement.

• Acted as an integral backend core API team member, integrating gRPC and Protocol Buffers for microservices expansion, enabling real-time messaging functions;
• Leveraged ElasticSearch's query scripts functionality to develop and implement chat rotation scripts, improving retrieval efficiency by ~40%;
• Maintained and implemented new features in a microservice managing 1 million concurrent WebSocket connections;
• Designed and implemented scalable backend solutions using Golang;
• Integrated Redis for efficient session management and caching, improving the responsiveness and reliability of the chat platform;
• Developed monitoring and logging solutions to maintain system health and performance;
• Created and deployed LiveChat bot integrations, enabling seamless functionality with various messaging platforms like Facebook Messenger.

The project involved working on the company's order management system between warehouses and stores. This system handled substantial data sets, ensuring that store managers could access the actual state of items in given warehouses. The project involved extensive data analysis and processing to optimize inventory management and improve operational efficiency.

• Developed and maintained the order management system, facilitating smooth operations between warehouses and stores;
• Handled and processed large data sets to ensure accurate and up-to-date inventory information for store managers;
• Contributed to systems integration with an additional currency, which led to opening stores in new countries;
• Implemented AWS DevOps/configuration tasks, including relocating servers between data centers with minimal unavailability and setting up API Gateways, EC2 instances, and other services;
• Conducted extensive data analysis to optimize inventory management and order processing, improving overall system efficiency;
• Contributed to the development of a Redistribution Algorithm, which improved inventory utilization and ensured timely deliveries, enhancing customer satisfaction;
• Implemented continuous integration and deployment pipelines using Jenkins.