Deep understanding of OOP concepts, design patterns, data structures and algorithms.
My strong part is backend, mainly Node.js ( I use in my projects it since it first appeared), also PHP. I have very strong SQL database experience (mainly MySQL and PostrgreSQL), as well as NoSQL databases (MongoDB, Redis), message queues like RabbitMQ.
The frontend stack is PHP (Yii and Laravel), Javascript (jQuery, Vue.js).
As Mobile Application Developer I have a very strong footprint in Android (Java and Kotlin). I prefer MVVM design pattern, reactive programming with RxJava (v2).