- worked in an agile environment with often requirements changes, converting an idea to a fully functional platform for real-time study time management, used by tens of thousands of students, over a period of 5 years- collaborated with the client to transform his requirements into application features, while being actively involved in product development and UI/UX design decisions- developed backend monolith application in Spring Boot with MySQL database- led the development of web application with a rich user interface, using React with Redux for managing complex state and Styled Components for styling- applied many database migrations in production and optimized application performance by indexing appropriate columns in the database- designed a complex recursive algorithm for task completion prediction- built a custom calendar component using the FullCalendar library- made a custom calendar picker component in React Native mobile app- developed Node.js (Express) microservice for managing calendar events, stored in DynamoDB- implemented task notifications on mobile and web applications, with Firebase- implemented different ways and tiers for purchasing application membership (subscriptions, lifetime), by integrating Stripe and Braintree (PayPal)- migrated 5 years old mobile application to the new React Native version with updating all dependencies and published it to Play/App Store.- migrated 7 years old Spring Boot application to the new version- developed a subscription-based payment model for purchasing app membership from the marketing website, using Java and Stripe Billing- enabled affiliates and referrals with a custom AffiliateWP integration

- developed multiple startup projects, in a team of 2 to 5 people, while making decisions about software architecture and a technology stack, reviewing code, and mentoring- built crypto payments processing system- defined complete software infrastructure on AWS, with a CI/CD pipeline- increased scalability and saved cost by utilizing serverless architecture with SST- built performant frontend applications with React, handling server-side data with React Query- implemented pixel-perfect responsive designs, using Tailwind CSS- created UI components in isolation (component-driven design) using Storybook- quickly built user interfaces with UI libraries like MUI and Ant Design- reduced time to market by utilizing the Hasura engine, with its features such as generating GraphQL API, role-based permissions, and event triggers- implemented authentication and authorization with AWS Cognito and Auth0- made onboarding users easier by developing the WooCommerce plugin for crypto payments- optimized specific operations, like creating a reminder on task creation, by writing stored procedures and triggers in PL/pgSQL- used Prisma to define a model, write queries and handle database migrations- built a cross-platform mobile app for real-time event tracking in React Native- developed console UI for vector database startup using React- worked on mobile application for retailers, enabling them to search products and create orders

- built REST API for the wholesale marketplace startup in Spring Boot, having features such as referrals, discounts coupons, making orders, etc.- designed database schema and its implementation in PostgreSQL- enabled ordering products and payouts to sellers by utilizing Stripe Connect- wrote tests for the payment part of the application, using JUnit and Mockito - optimized searching products, by implementing full-text search with the Algolia search engine

- worked on a crowdfunding platform for startups and a platform for the secondary market, in a scrum team of 10 people- built backend REST APIs with Spring Boot and Express, saving data in PostgreSQL and MongoDB database- utilized microservice architecture with Docker and Kubernetes- improved security, by blacklisting authorization tokens, stored in Redis for faster access- created a domain-specific language for voting system specification, using textX meta-language

- developed a web-based platform, supporting a business with 3D scans, using AngularJS and Java EE- generated code for the ERP system, using Xtext and Xtend- wrote SQL queries for fetching data from an Oracle database with a large and complex schema- built Electron desktop application for employees, with time tracking and reporting functionality