Sergey is available for hire

Sergey Royz

Verified Expert in Engineering

Software Developer

Location

Prague, Czech Republic

Toptal Member Since

January 13, 2015

Sergey is a highly skilled software engineer with over 15 years of experience in development and architecture design. He worked for fintech startups, medical companies, the travel industry, and home automation. He has a strong understanding of OOP and FP concepts and experience with applying design patterns. Sergey prides himself on his ability to create robust and maintainable code.

Full-stack Development Web Scraping Full-stack Code Review Data Engineering Web App Development Airtable REST APIs JavaScript GitHub Java Automation React Open Source Cloud Rancher Plotly

Portfolio

Swipelux OU

Web3, Spring Boot, Docker, Kubernetes, PostgreSQL, Blockchain, Ethereum...

Toptal Clients

Koa, Node.js, Spring Boot, Docker, Amazon Web Services (AWS), SAML-auth, React...

Absa

Apache Spark, Plotly, Python 3, Docker, Rancher, SQL, Jira, JavaScript...

Experience

JavaScript - 12 years Java - 9 years SQL - 9 years Python - 7 years Hibernate - 5 years Spring MVC - 4 years Spring - 4 years AngularJS - 1 year

Availability

Part-time

Preferred Environment

MacOS, Vim Text Editor, Git, IntelliJ IDEA, Visual Studio Code (VS Code), Sublime Text 3

The most amazing...

...thing I've built was a fully working fiat to a crypto payment gateway, including integrations with an exchange, KYC provider, and multiple blockchains.

Work Experience

CTO | Co-founder | Full-stack Engineer

2020 - PRESENT

Swipelux OU

Built a prototype from scratch, a widget allowing processing payment cards, an integration with a Know Your Customer (KYC) provider, and an integration with a crypto exchange.
Led technical communication with investors during the pre-seed round of investments.
Spearheaded the development process, managing a team of 8–10 people and negotiating with business and development.

Technologies: Web3, Spring Boot, Docker, Kubernetes, PostgreSQL, Blockchain, Ethereum, Smart Contracts, Amazon Web Services (AWS), Cryptocurrency, Bots, Decentralized Finance (DeFi), Team Leadership, Leadership, Payment APIs, Technical Leadership, Architecture, API Integration, REST APIs, Data Engineering, Open Source, Cloud, API Documentation, Web App Development, Full-stack, Full-stack Development, DevOps, GitHub, AWS Lambda, React, Material UI, CSS3, Flutter, Data Visualization, Database Modeling, Automation Scripting, Scripting, Admin Panels, Automation, Vue 2, Airtable

Senior Full-stack Engineer

2018 - PRESENT

Toptal Clients

Automated data flow with a Selenium WebDriver and UI Automator.
Implemented many integrations of IoT devices via REST API, MQTT, and Apache Pulsar.
Implemented Security Assertion Markup Language (SAML) integration into an existing solution.
Applied a user-management console with React and Koa.js.
Developed multiple microservices and split monolith app.
Developed firmware update solution for IoT devices using AWS infrastructure (S3, SNS, SQS, MQTT).

Technologies: Koa, Node.js, Spring Boot, Docker, Amazon Web Services (AWS), SAML-auth, React, Redux, Python 3, SQL, JavaScript, Spring MVC, Spring Security, Code Review, Source Code Review, Algorithms, ESP32, Arduino, CSS, HTML, Web Scraping, APIs, Bots, Architecture, API Integration, REST APIs, Data Engineering, Open Source, Data Science, Cloud, API Documentation, Web App Development, Full-stack, Full-stack Development, DevOps, GitHub, AWS Lambda, Dashboards, Material UI, CSS3, Responsive Web Design (RWD), Internet of Things (IoT), Data Visualization, Database Modeling, Automation Scripting, Scripting, Admin Panels, Automation, Vue 2, Airtable

Data Science Engineer

2020 - 2021

Absa

Implemented rules for a rule-based anti-fraud detection engine.
Managed, implemented, and deployed a BI dashboard POC with Plotly.
Provided training on the usage of internal deployment automation tools such as Rancher and Subatomic.

Technologies: Apache Spark, Plotly, Python 3, Docker, Rancher, SQL, Jira, JavaScript, Code Review, Source Code Review, Interviewing, Flyway, HTML, APIs, Payment APIs, Architecture, API Integration, REST APIs, Data Engineering, Data Science, Cloud, API Documentation, GraphQL, Full-stack, Full-stack Development, DevOps, GitHub, React, Dashboards, Data Visualization, Database Modeling, Automation Scripting, Scripting, Admin Panels, Google Sheets, Automation, Vue 2

Senior Software Engineer

2018 - 2019

Omio (formerly Goeuro)

Implemented several integrations with ferry ticket providers.
Dockerized and deployed microservices to Kubernetes.
Redesigned the flow of the integration development to be more modular and testable.

Technologies: Spring Boot, SOAP, Kubernetes, Docker, Jira, JavaScript, Spring MVC, Code Review, Source Code Review, HTML, APIs, Technical Leadership, Architecture, API Integration, REST APIs, Open Source, Cloud, API Documentation, GraphQL, Web App Development, Full-stack, Full-stack Development, DevOps, GitHub, React, Database Modeling, Automation Scripting, Scripting, Admin Panels, Google Sheets, Automation

SAML Developer

2017 - 2018

Radix Health

Developed a SAML integration to an existing Spring-based application allowing authorization to users via a third-party identity provider (IdP).
Implemented integration with Shibboleth using PHP.
Effectuated a user and key management admin console with Koa.js and React.

Technologies: Spring Security, Java, SAML, Spring, SAML-auth, PingFederate, API Integration, REST APIs, Cloud, API Documentation, Full-stack, Full-stack Development, GitHub, Database Modeling, Automation

Senior Software Engineer

2017 - 2018

Cisco

Extracted microservices from the monolithic architecture.
Dockerized microservices, wired them together with Docker Swarm for the PoC.
Worked on migrating the microservice infrastructure to AWS.
Prepared data for cognitive threat analysis of the machine learning models.

Technologies: Spring Boot, Amazon Web Services (AWS), Docker, Machine Learning, Terraform, Python, SQL, Jira, JavaScript, Spring MVC, Code Review, Source Code Review, HTML, APIs, Architecture, API Integration, REST APIs, Data Engineering, Cloud, API Documentation, Web App Development, Full-stack, Full-stack Development, GitHub, Database Modeling, Automation Scripting, Scripting

Senior Software Engineer

2016 - 2016

Hewlett Packard Enterprise

Maintained current solution of operations and log analysis.
Implemented a Slack chatbot for automating the development pipeline.
Worked on dockerization of an existing solution for operations analytics.

Technologies: Docker, Spring Boot, CoffeeScript, Spring MVC, APIs, API Integration, REST APIs, Cloud, API Documentation, GitHub, Database Modeling

Lead Software Engineer

2012 - 2016

Instabank

Created architecture and developed a back end for upupapp.com.
Implemented various integrations with banking systems.
Developed integrations with internal banking systems.
Applied account status and statement report module.

Technologies: MongoDB, PostgreSQL, Scala, Play Framework, Django, Python, Hibernate, Spring, Java, SQL, Jira, JavaScript, Spring MVC, Code Review, Source Code Review, Interviewing, Web Scraping, APIs, Technical Leadership, Architecture, API Integration, REST APIs, Cloud, Database Modeling, Scripting

Lead Software Engineer

2011 - 2012

iDaMobile

Implemented mobile banking apps for five banks in Russia.
Programmed a back end for a mobile banking solution.
Integrated a mobile banking solution into a bank's infrastructure.

Technologies: Python, PostgreSQL, Android, Jakarta EE, SQL, JavaScript, Spring MVC, Code Review, Source Code Review, Interviewing, Web Scraping, APIs, Technical Leadership, Architecture, API Integration, REST APIs, Cloud, GitHub, Scripting

Lead Software Engineer

2010 - 2011

NetCracker

Performed business analysis of the projects at customer's site in Malaysia.
Implemented a J2ME App for Blackberry and integrated it with the platform.
Architected and implemented a high-performance distributed management system of network devices.

Technologies: SOAP, Jakarta EE, J2ME, SQL, Spring MVC, Oracle, Code Review, Source Code Review, Interviewing, APIs, Architecture, API Integration, REST APIs, Scripting

Software Engineer

2009 - 2010

Yandex

Supported integration and deployment.
Improved internal analytical tools.
Integrated an internal data mining tool into the project.

Technologies: Swing, MySQL, Jakarta EE, SQL, Spring MVC, API Integration, REST APIs, GitHub

Senior J2EE Developer

2005 - 2009

NetCracker

Developed a plugin for Eclipse for the graphical merge of business process diagrams.
Performed platform customization for the customer's needs.
Implemented LDAP integration.
Provided product support at a customer's site in Belgium.
Worked as Java instructor in a learning center.

Technologies: Web Services, Oracle PL/SQL, Jakarta EE, SQL, Spring MVC, Oracle, API Integration, REST APIs

Experience

Rapid Card2Card Transfer Service

A service that allows rapid card-2-card transfers by providing integration with a third-party payment gateway. The service is a peer-to-peer payment solution, with no registration needed.

I developed the project from the early stages to production.

Kwenda: Tourist City Guide for Android

An app which integrates with point of interests, shows routes, and allows object filtering by type.

Clustering large sets of objects on the map

I implemented an algorithm for building static clusters of geolocations and pre-calculating them for different zoom levels. I integrated it with a mobile banking app and it works in production, perfectly handling more than 50k objects.

The towers of Hanoi game

An Android game where users have to move disks from one rod to another. I've implemented nice touch-screen user interaction.

Huffman Code Implementation with Python

The project's aim was the Python implementation of a compression algorithm using Huffam codes. It builds a binary tree based on the given input string. The path to the leaf element is encoded by a sequence of '0' and '1' representing the shorter than 8-bit code of a character used to compress new data.

Flat-sharing Platform: Coliver

A platform for searching for future flatmates for sharing an apartment rental in big cities. I was a full-stack developer and implemented an MVP from scratch. The back end was implemented in Java/Spring Boot, the front end was implemented with Vue, and the service was run on Kubernetes.

Skills

Languages

Java, JavaScript, HTML, Python, CSS, SQL, CSS3, HTML5, Bash Script, Scala, CoffeeScript, Python 3, SAML, GraphQL

Libraries/APIs

React, REST APIs, Vue, Vue 2, Node.js, jQuery, PyTorch

Tools

GitHub, Vim Text Editor, Jira, Git, Flyway, Google Sheets, IntelliJ IDEA, Sublime Text 3, Terraform, Plotly

Paradigms

Automation, Functional Programming, Concurrent Programming, Design Patterns, Object-oriented Programming (OOP), DevOps, Responsive Web Design (RWD), Data Science, REST

Storage

Database Modeling, PostgreSQL, MongoDB, Oracle PL/SQL, MySQL, PingFederate

Other

Code Review, Source Code Review, Web Scraping, APIs, Bots, Architecture, API Integration, Data Engineering, Web App Development, Full-stack, Full-stack Development, Automation Scripting, Scripting, Airtable, Machine Learning, Interviewing, Cryptocurrency, Decentralized Finance (DeFi), Technical Leadership, Open Source, Cloud, API Documentation, Dashboards, Internet of Things (IoT), Bluetooth, Hardware, Data Visualization, Admin Panels, Web Services, SOAP, Robot Operating System (ROS), SAML-auth, Algorithms, ESP32, Web3, Smart Contracts, Scraping, Team Leadership, Leadership, Payment APIs

Frameworks

Flutter, AngularJS, Spring Security, Spring MVC, Hibernate, Spring, Material UI, Swing, Play Framework, Django, Spring Boot, Koa, Redux, Apache Spark

Platforms

Android, Kubernetes, Blockchain, AWS Lambda, Jakarta EE, J2ME, Oracle, Visual Studio Code (VS Code), Docker, Amazon Web Services (AWS), Rancher, Arduino, Ethereum

Education

2006 - 2009

Master's Degree in Computer and Information Science

Moscow Institute of Physics and Technology (State University) - Moscow, Russia

2003 - 2006

Bachelor's Degree in Applied Mathematics and Physics

Moscow Institute of Physics and Technology (State University) - Moscow, Russia

Certifications

JANUARY 2021 - PRESENT

CSMM.103x: Robotics

edX

SEPTEMBER 2020 - PRESENT

Certified Rancher Operator: Level One

Rancher Labs

AUGUST 2019 - PRESENT

AI for Everyone

Coursera

JANUARY 2014 - PRESENT

Functional Programming Principles in Scala

Coursera

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