✓developed and extended identity provider using - backend JBoss AS and Java, frontend React. Increasing online users to 12K+. ✓designed architecture and developed Gatekeeper service using - Golang, HTTP library, and API. Increasing stability rps to 17k+✓successfully generated unit and functional tests, and increased test coverage from 24% to 86% (JUnit and GoUnit).Technologies: Golang, Java, React, Keycloak, JWT, JBoss AS, Doсker, Kubernetes, AWS, Github CI/CD, Helm charts

✓designed moving and moved all cache from Memcached to Redis (more than 1 500 000 pages). Query time has been reduced x2 from 1 ms to 0,5 ms and throughput has been increased almost x2 from 50k qps to 90k qps compared to Memcached.✓designed and implemented a cache granulation system with the ability to partially clear it on demand. This made it possible to smooth out the peak of web transaction time from 800 ms to 500 ms at the moment of uploading to production.Technologies: Redis, Memcached, Ruby, Ruby on Rails, TSQL, Github

✓designed architecture and developed OAuth2.0 authorization service https://id.novaposhta.ua/ by Golang – increasing stability rps to 30k+✓separated backend for registration, two-factor authentication, and recovery access as micro-services using Golang - increasing fault tolerance main system on 30% ✓integrated two incompatible legacy services, by creating an adapter - reverse proxy server - using Golang, HTTP library, gRPC, API – reduce development costs 10%✓implemented CI/CD pipeline for the OAuth2.0 system, with help of Jenkins. The pipeline builds systems, runs unit tests, integrations tests, etc, and deploys the app to the environment.Technologies: Golang, PHP, gRPC, OAuth2.0, Ory Hydra, Jenkins, Bitbucket, PostgreSQL

✓produced backend for mobile applications “Nova Poshta” (in App Store and Play Market 5,000,000+ installs) – using native PHP7.2, REST API✓implemented backend for SPA https://novaposhta.ua/ – using Yii PHP framework, CSS, JavaScript/jQuery, REST, MySQL✓created e-commerce sites integrated with privatbank.ua, easypay.ua, and other payment gateway APIs – this helped to double the volume of non-cash transactions in the next year. Technologies: PHP7.2, Javascript, MySQL, Golang, REST API, CSS, Git, Composer

✓revamp internal websites from front to backend - using PHP, Laravel, ExtJS, and HTML - website loading speed has increased by 3 times✓authored integration Google Geocoding and Google Maps API – using PHP Laravel, ExtJS, JavaScript - it became possible to build routes online on the map – it helped speed up the work of the department of logistics by 100%, the number of service vehicles indicators have doubled too✓contributed “scanning app” on Barcode Scanner Motorolla MС3190 – using Python, Tkinter GUI toolkit, Windows CE 5.0 - the number of scanned parcels per shift improved in 5 times✓improved performance of several critical SQL-queries in 2-6 times – added new indexes, replaced correlated subqueries by JOIN operator✓successfully generated unit and functional tests – using PHPUnit, reduced manual testing by 20%✓promoted from software engineer to the team lead by demonstrating leadership potential and training junior developers – usually, it takes min 3 years completed in 2 Technologies: PHP, Javascript, Python, Tkinter, HTML, Laravel, MySQL