Viacheslav Kysil

Web Dev (Ruby on Rails, JavaScrip and Elixir) consultant.
I help digital entrepreneurs to turn their ideas into robust, performant and secure web applications.

Hello, I am a web engineer specializing in building web applications, APIs, and JavaScript user interfaces. I have experience with all stages of the development cycle - from writing code to deployment and managing the application in production.

My primary specialization is SaaS applications and most of the items in my portfolio are SaaS projects.

I am also the head of VK Development Lab agency - we are a team of experts in Ruby, Elixir, and JavaScript.

We can use our skills and expertise to build for you a web application of any size, secured with authentication and authorization systems, database support, and background processes for performance optimization. We always cover our code with automated tests so there will be no vendor lock up - if you ever want to switch to another software developer or team, they will able to apply modifications with confidence.

What you'll get for your money:

  • Security. I won't disappear from you in the middle of a job.
  • Reliability. Once we agree on a task, you will get it exactly the way we've discussed it.
  • Consistency. You'll get the same level of high-quality work from start to finish.
  • Initiative. I'll contribute ideas, help to define your requirements, and ask questions along the way.

Feel free to reach out to me anytime. I am looking forward to building your awesome web project together!

Personal Info

Languages English, Russian
Date of birth 02 February 1990
Location Tallinn, Estonia, EU

Main areas of expertise

  • Ruby
  • Ruby on Rails
  • Sidekiq
  • Active Job
  • RSpec
  • Capybara
  • JavaScript
  • ReactJS
  • Webpack
  • TypeScript
  • FlowType
  • SASS
  • Caching in Rails
  • PostgreSQL
  • Redis
  • Git
  • Nginx
  • Deployment


Work experience

Independent Ruby on Rails and JavaScript consultant

June 2017 - present

Nowadays I work as Lead developer and consultant on enterprise projects built with Ruby on Rails and React.js.

Senior Web developer

April 2016 - June 2017 (Flatstack, Kazan, Russia)

I was working as a Lead developer on various projects built with Ruby on Rails. At Flatstack I was responsible for backend development (high-load, scalability), client-side development with React.js, SQL queries analysis and optimization (for PostgreSQL), sprints planning, mentoring junior and middle employees. I also got familiar with RADIUS authentication and captive portal development.

Ruby on Rails and JavaScript developer

February 2015 - March 2016 (Racoons Group, Kazan, Russia)

I transitioned fast from member to lead developer of a team responsible for one of the largest company projects: Solution stack was as follows: Ruby on Rails, Angular, MySQL. My responsibilities included client and server-side development, code review and deployment.

While I worked at Racoons Group I mastered my skills as Ruby and JavaScript developer and with SQL queries; got experience with CoffeeScript, Angular and backend API development; got experience with implementing real time data update systems (using Websockets). Also, in cooperation with other developers, I increased both application client-side and server-side scalability and speed.

Web developer

August 2014 - February 2015 (Freelance)

Developed front end and back end of JavaPractice online service: java programming problems archive with automatic solution verification system. Technologies used: AngularJS, CoffeeScript, Spring Framework, MySQL, and JUnit with Jasmine for testing. During this period I got experience with building client-side applications in Angular; VPS administration and setup experience (Nginx, Tomcat, Java application deployment); experience with building backend APIs using Spring framework




Bachelor of Engineering




2017 - Present
New York, USA

Rhino is a real estate technology company replacing security deposits with a smarter alternative that’s better for both renters and landlords.
Since 2017 I am working as a Senior software engineer developing Ruby on Rails backend and React.js/TypeScript client side. Major achievments: built MVP almost from scratch; added integration with Yardi Voyager, developed recurring subscriptions flow with multiple Stripe accounts; built complex automatic reporting system for insurance partners.

Tags: Ruby on Rails PostgreSQL Elixir PhoenixFramework REST API React TypeScript Flow Webpack Sidekiq RSpec Capybara CanCanCan Stripe


2017 - Present
Austin, TX, USA

Nucleus (former Mastermind Manager) is set of essential tools for communities and mastermind groups management, brainstorming, goal setting and accountability.
I am a Lead engineer on this project. Together with my team we've build application from sratch using Ruby on Rails and React/Redux. We also implemented WebRTC video integration with major platforms like, Twilio, Jitsi Meet. Developed integration with Stripe and Mailchimp/Mandrill, and later replaced Mailchimp email templates builder with own custom solution.

Tags: Ruby on Rails PostgreSQL Elixir PhoenixFramework REST API React Redux Webpack Sidekiq RSpec Capybara Pundit Stripe DigitalOcean Mattermost server


2019 - Present
Tallinn, Estonia

Form2chat is a serverless form backend that allows you not only to setup working web forms in just a couple minutes but also receive your submissions directly to the messenger of your choice: Telegram, Viber, Facebook Messenger, Slack or integrate your forms with other popular apps via Zapier.

I am a Lead engineer on this project and together with my team built integrations with major chat platforms and Zapier, spam protection filters, auto-responses with custom email templates, and also subscription payment system through gateway.

Tags: Ruby on Rails PostgreSQL Redis Sidekiq RSpec Capybara Digital Ocean
Flight School<br /> Manager

Flight School

2019 - 2020
West Jordan, UT, USA

Flight School Manager is a powerful all-in-one tool to manage flight school. I worked as Elixir and PhoenixFramework developer on this project and was responsible for development of web dashboard and API for iOS application.

Major milestones:

  • Built an automatic payment system that invoices user using flight data (via Stripe)
  • Added schools onboarding flow
  • Implemented Document Management System‎

Tags: Elixir PhoenixFramework React.js ExUnit Wallaby Heroku Stripe
Kindra Connect

Kindra Connect

2020 - Present
California, USA

Kindra Connect brings together people who share the values of authenticity, kindness, community, creativity, play, and personal growth. Together with my team, I am working as a Senior Elixir developer on this project and I am responsible for building and maintenance of Elixir/Phoenix API server for Kindra mobile application. I also support and expand admin dashboard built with React.js.

Tags: Elixir PhoenixFramework Amazon EC2 JavaScript React Redux PostgreSQL


Paris, France

Blackink project goal was to simplify paywall ingration for news and magazine publishers and provide an all-in-one platform both for readers and publishers. As a developers team lead, I managed work on 3 separate projects for this client:

  • Analytics API to track customers behaviour through payment flow (Elixir and PhoenixFramework)
  • Readers dashboard with purchases and wallet (Ruby on Rails)
  • Lightweight javascript paywall library to be embedded to publishers websites

Tags: Elixir PhoenixFramework Ruby on Rails Amazon JavaScript Preact Redis


Zürich, Switzerland

Jurata is the best lawyers database Switzerland. I, as a Ruby on Rails developer, was responsible for project maintenance, features and ingerations development. While working on Jurata I significantly improved customer data flow between, and Jurata database.

Tags: Ruby on Rails PostgreSQL Redis Sidekiq RSpec Capybara Heroku Segment Intercom
Rhino API

Rhino API

New York, USA

RESTful JSON API for partners built with Elixir and PhoenixFramework. I developed this project from scratch.

Tags: Elixir PhoenixFramework Amazon EC2



A canadian job board. I have been a lead developer on this project for a few months. I was responsible for architecturing and implementing RESTful API endpoints using JSON API specification, code review, maintenance, tasks estimation and sprint planning.

Tags: Ruby on Rails PostgreSQL REST API RSpec React Redux Capybara Sidekiq Pundit


2016 - 2017
Vancouver, Canada

ACL™ GRC— a flexible and easy way to manage the process of planning and organizing projects, assessing risk, analyzing data, communicating issues, and visually sharing your findings. I've been one of senior full stack developers in distributed R&D team for 7 months. Was responsible for task planning, estimation and backend/frontend development. While I was working on the project together with the team we successfully delivered 3 major epic stories and also won an internal hackathon by developing bulk upload feature based on react-data-grid.

Tags: Ruby on Rails PostgreSQL REST API RSpec Capybara React Redux Delayed Job CanCanCan
Premium Parking

Premium Parking

New Orleans, LA, USA

I have been working on this project for a few months with a team of fellow developers. My responsibilities included server side development and maintenance, code review, deployment, tasks estimation and sprint planning.

Tags: Ruby on Rails PostgreSQL Redis MemCachier Delayed Job REST API Rspec
Captive portal<br/>with admin dashboard

Captive portal
with admin dashboard

Charlotte, NC, USA

This is a custom captive portal implementation for an enterprise wifi network run by I've been working on as a Ruby on Rails developer on this project for and implemented radius client tool, admin dashboard and various background jobs via ActiveJob and Sidekiq, mailers, JSON API, etc.

Tags: Ruby on Rails PostgreSQL Sidekiq Microsoft Azure REST API RSpec jQuery
Interneturok HomeSchool

Interneturok HomeSchool

February 2015 - March 2016

This is online school education project. I worked on it for more than a year and transitioned from a regular to lead developer. Achievments: designed and developed a new internal chat system, online exam feature, pupil and teacher journals. Improved pages response time. Significantly improved deployment process and decreased deployment time from 11 minutes to less than one.

Tags: Ruby on Rails MySQL Sidekiq Grape REST API RSpec AngularJS CoffeeScript Grunt Jasmine
RadiusClient gem

RadiusClient gem

May - June 2016

Ruby Library for interacting with freeradius server. While working at Flatstack I was developing a captive portal for and it required a library to establish interaction between Ruby on Rails server and RADIUS server. I took an old and outdated library and developed it further to support current stable version of freeradius server. This project helped me to get experience with RADIUS authentication and captive portal development.

Tags: Ruby Gem building FreeRadius
JavaPractice Service

JavaPractice Service

October 2014 - March 2015

This project is Java programming problems archive with automatic solution verification system. Client's goal was to develop such service as an addition to his other project focused on java programming education. My contribution to this project was a whole client side application built with AngularJS, written in CoffeeScript and completely covered by Jasmine specs. I also designed and developed some backend API endpoints and services. As a result of my work problem-solving part of this service was fully completed.

Tags: AngularJS CoffeeScript Grunt Jasmine Java 7 Spring Framework Tomcat jUnit

Open Source contributions

Contributed to various Ruby, JavaScript and Elixir libraries like Timex, Jitsi Meet (from Atlassian), React Currency Input, etc. Developed own open source projects: React Month Picker and React Popover Component. Arctic Code Vault Contributor.

Tags: Ruby Elixir JavaScript TypeScript React.js Redux


List of things I can do to help your business grow

Web Development

I'll turn your business idea into a web application. Either you may delegate me the responsibility for the whole development process, or I can join your developers' team and help with project delivery.

Code Review

Daily regular or upon request code review to help to improve code quality, get a second opinion on complicated problems, share knowledge of best practices and design patterns.

Security Audit

I will analyze an application code and deliver a detailed report of security vulnerabilities found in your application and instructions on how to fix them.

Perfomance Audit

I will analyze an application code, run benchmarks and deliver a list of possible performance optimizations and instructions on how to implement them.

Infrastructure Setup or Migration

Servers setup or migration from any cloud to any cloud: Heroku, Digital Ocean, AWS, Google Cloud, etc.


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Bryan Woods

Rhino Labs, Co-Founder & CTO

Slava is far and away one of the strongest engineers I've ever had the chance to work with in my 15+ years of building software products and teams. He is a thoughtful, skilled software engineer and contributor. He asks all the right questions to thoughtfully build systems not just to spec, but for the future of the business, ensuring that code quality remains high and that the projects can continued to be iterated on rapidly well into the future. He's been working for us for more than three years now, and I look forward to continuing to work with him for as long as he'll have us!

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Sebastian Broways

Head of Product, Cofounder of Mastermind Manager

Slava has been one of the most excellent individuals with which I've had the opportunity to work. Not only is he a competent developer, what makes Slava so great to work with is all the other intangibles. His willingness to jump on any project. His thoughtfulness about what would make the product better and business successful. He's both a capable leader and developer. Whatever project you bring him in on, he will make you feel like he's a partner. He has a great attitude and I hope we will continue to work together for years to come. If you have the opportunity to work with him, you should jump on it.

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Liliya Sabitova

Senior Product Manager at

Slava is a very experienced, knowledgeable and responsible professional to work with. His broad expertise allows him to ramp up with new projects very quickly. What I especially liked about working with him is that he always strives to do things the right way - code quality, stability and test coverage are something that he keeps a close eye at, thus our clients with technical background had the most positive feedback regarding his work. All in all, Slava proved to be a great team member as well as a team lead - he was leading the development in quite a few projects that we had within the company. I’d highly recommend Slava as a very skilful developer.

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David Roegiers


Slava was my go-to coder for a Rails app in production during a couple of months. I was very happy working with Slava. He always understood my requirements fully and even thought ahead suggesting solutions to unforeseen problems. He was not afraid to tackle a broader field of issues and tech : from FE to DevOps. He is a man of effective words : he communicates when it's relevant - not more, nor less.

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Murat Alpman

Entrepreneur, Innovator, Geek

Slava is one of the best programmers I have ever met if not the best. I highly recommend him.


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