Vladimir Kravchenko, Developer in Playa del Carmen, Mexico
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Vladimir Kravchenko

Verified Expert  in Engineering

Full-stack Developer

Playa del Carmen, Mexico
Toptal Member Since
August 22, 2016

With a strong scientific background, Vladimir knows how to handle tricky problems and chases quick and elegant solutions. He's a generalist, always striving to use the best-suited technology for each project instead of always gravitating to the most well-known one. He is also dedicated to pixel-perfect solutions and integrates well with either a front-end or back-end team.


Haven Connect
Elixir, CSS, React, Architecture, JavaScript, SQL, GraphQL, PostgreSQL...
Knowsis Limited
Elixir, Chrome Extensions, Full-stack, Full-stack Development, API Development
Metalink Labs
Elixir, Phoenix, Vue, PostgreSQL 9, Amazon Web Services (AWS), Discord Bots...




Preferred Environment

Visual Studio Code (VS Code), Git, Unix

The most amazing...

...project I've made was 3D planning software to minimize the effective dose of human radiotherapy cancer treatment, using Monte Carlo methods.

Work Experience

Elixir CSS Developer

2021 - PRESENT
Haven Connect
  • Implemented a new version of an interviewing questionnaire in React using MUI (Material UI).
  • Set up a scoring system for the questionnaire results.
  • Created an internal dashboard search engine across the questionnaire data.
  • Reorganized the development process to use linting and reusable components and updated the existing CI solution to include checks that improved the deployment process and reduced the number of bugs.
  • Maintained and improved the GraphQL API integration using Elixir's Absinthe on the back end and Apollo on the front end.
  • Introduced Elasticsearch integration for data indexing and performance optimizations.
  • Implemented performance profiling and optimizations on the app's slowest parts, resulting in 2-10x speed improvements.
Technologies: Elixir, CSS, React, Architecture, JavaScript, SQL, GraphQL, PostgreSQL, Relational Databases, Elasticsearch, APIs, API Integration, Material Design, TypeScript, Full-stack, Back-end, API Development

Elixir Developer

2024 - 2024
Knowsis Limited
  • Updated the stack from the legacy version to the recent. Switched the majority of the views to be LiveViews.
  • Updated the React browser extension to collect new form data and send it to the API.
  • Implemented the ability to take screenshots and upload them to an AWS S3-compatible system.
  • Implemented a new permissions system for team management.
  • Added a CSV data uploader/parser on the main app side.
Technologies: Elixir, Chrome Extensions, Full-stack, Full-stack Development, API Development

Back-end Elixir Developer

2021 - 2022
Metalink Labs
  • Designed and developed a messaging app for Web3 in a team of five featuring Ethereum-based login for an NFT marketplace.
  • Designed and implemented a push notification system for the main app.
  • Optimized the database storage of the user wallet holdings information to be able to keep in sync over 1 million records with the blockchain and provide permissions based on those holdings.
  • Set up the integration with external APIs to receive/process time-sensitive data to be sent via notifications.
  • Designed an API architecture to receive data from a third party securely. Set up a bot to fetch the data from Discord and Twitter and pass it to the main application.
Technologies: Elixir, Phoenix, Vue, PostgreSQL 9, Amazon Web Services (AWS), Discord Bots, Twitter API, Ethereum, Architecture, APIs, API Integration, Back-end, API Development

React Developer

2019 - 2021
Spencer Health Solutions Inc
  • Developed an internal dashboard to manage users' data and control billing using React.
  • Implemented a WebRTC call functionality between the web client and device (React/React Native).
  • Migrated the old Angular functionality to React and ensured that code was up to date and industry standards.
Technologies: React, AngularJS, Git, Bitbucket, React Native, Jira, APIs, API Integration, Material Design

Meteor Developer

2018 - 2019
Community Technology Alliance
  • Migrated client profile and client enrollment management to React.
  • Helped to create a new GraphQL API to substitute an elder REST API.
  • Upgraded a surveying app to the new external API version.
  • Implemented a separate feature to extract data from uploaded files and send it to an external API.
  • Supported the existing production application and fixed bugs and issues.
Technologies: Git, HTML, MongoDB, JavaScript, NoSQL, OAuth, Meteor, React, Node.js, APIs, API Integration, Full-stack, API Development

Full-stack Developer

2017 - 2019
  • Created an application to enroll new workers or participants using React and Phoenix frameworks.
  • Created a timesheet management application using React and Phoenix frameworks.
  • Created a dashboard application for internal managers to process data from other applications.
  • Integrated a document management system into the enrollment application to support e-doc to paper conversion.
  • Optimized SQL data storage and querying to get around five times faster responses from complex data requests.
  • Implemented automated data validation and reports.
Technologies: Git, HTML, Erlang (OTP), PostgreSQL, JavaScript, SQL, Phoenix, Elixir, React, APIs, API Integration, Full-stack, Back-end, API Development

Elixir Developer

2016 - 2017
Betty Blocks
  • Implemented significant parts of the new back end, including core features and external service integrations.
  • Helped to rewrite a custom language parser from Ruby to Elixir, complete with feature compatibility.
  • Optimized data processing to simulate object mutations using a functional paradigm with an ETS cache.
  • Supported implementing and testing full-feature parity between new and old back-end applications.
Technologies: Git, Ruby on Rails (RoR), Phoenix, Erlang (OTP), OTP, PostgreSQL, Ruby, Elixir, APIs, API Integration, Back-end, API Development

Senior Engineer

2015 - 2017
Urban Capital, Ltd.
  • Developed a search engine website using Meteor (Node.js and Blaze) and Google Maps for the front end.
  • Made web crawlers to scrape and parse real estate sites using Python's ScraPy and NTLK (natural language processing).
  • Optimized a single-page application for search engines (SEO).
  • Created a tool to analyze properties and estimate prices. This tool also allows for price predictions based on multiple parameters and statistics.
  • Made a web crawler to parse popular Facebook posts and see the engagement on a selected theme (Selenium and Python's Newspaper).
  • Created a dashboard to manage users and data, including geolocation data.
Technologies: Git, Machine Learning, JavaScript, NoSQL, Data Science, Data Scraping, OAuth, MongoDB, Selenium, CSS, HTML, Meteor, Python, Node.js, APIs, API Integration, Scrapy, Full-stack

Meteor Developer

2015 - 2016
Fujikon Industrial Holdings, Ltd.
  • Optimized the Meteor+React-based chat app for 2000+ simultaneous connections.
  • Implemented email notifications for the above app.
  • Added an integrated TODO module.
  • Added a file-uploading module.
Technologies: Git, HTML, JavaScript, NoSQL, LDAP, NGINX, Meteor, MongoDB, Node.js, APIs, API Integration, Full-stack

Senior Engineer

2015 - 2015
  • Added back-end logic to designs provided.
  • Set up the server with an automatic deployment.
  • Consulted a team of developers on architecture, DevOps, and development.
  • Set up the JS front-end to manage REST API appointments.
  • Implemented an email notification system.
Technologies: Git, HTML, JavaScript, jQuery, PostgreSQL, Ruby on Rails (RoR), Ruby, APIs, API Integration

Web Developer

2014 - 2015
CTM, Ltd.
  • Made a solution for high-load server-server queues communications with , ~10,000 daily users, up to 3GB per file.
  • Integrated the solution with Russian customs.
  • Set up a remote server machine to host the application and queue.
  • Created a notification system to check project availability with SMS notification on Python.
  • Added a load balancer daemon to manage old SMTP- and new WebSphere-based services.
Technologies: WebSphere MQ, Subversion (SVN), C++, IBM WebSphere, PostgreSQL, Python, APIs, Full-stack

Senior Developer | Co-founder

2014 - 2015
Fcuking Easy CRM
  • Created a sales CRM system from the ground up. Currently, over 100 companies are using it.
  • Developed an online mail client to integrate deals with email threads using Gmail API.
  • Led a team of five, managing the tasks for both designers and developers.
  • Optimized project APIs to be ten times faster than using a basic Ruby on Rails solution using Rake, Grape, and EventMachine.
  • Created scripts for automatic deployment, backup, tests, and automated availability reports.
Technologies: Git, HTML, NGINX, Minimum Viable Product (MVP), JavaScript, OAuth, PostgreSQL, AngularJS, CSS, Gmail API, EventMachine, Ruby on Rails (RoR), Ruby

Senior Assistant Engineer

2011 - 2014
Scientific Research Institute of Blood Circulation Pathology
  • Created verification software to estimate the precision of a 3D 'effective dose' distribution in the human body using computer modeling.
  • Created a tool to recreate chemical data from computer tomography (DICOM) and insert it into modeling software.
  • Created a computer model of a medical linear particle accelerator with rotation and moving collimators (filters).
  • Simulated a real treatment process based on CERN's data of the passage of particles through matter. GEANT4.
  • Created a disturbed calculations system for treatment simulation.
  • Conducted experiments on the real device to calibrate the computer model.
Technologies: Minimum Viable Product (MVP), C++, Data Science, DICOM, Geant4

Senior Assistant

2010 - 2011
Budker Institute of Nuclear Physics
  • Created an “effective dose” calculation software for different human exposure inspection projections on X-ray inspection devices.
  • Analyzed estimated data for different projections to improve the inspection device. One such device is used at Tolmachevo International Airport.
  • Migrated the Linux-based calculation software to Windows.
  • Conducted experiments on the real device to calibrate the computer model.
  • Published a paper based on estimations and data analysis.
Technologies: Data Science, Geant4, C++

Urban Search

An Australian data-driven real estate search engine. I worked in a team of three on both back-end and front-end development.

Every building was rated and scored depending on various data sources like geolocation data, historical significance, etc. NLP also works on the front-end part of the project, making free text search possible (e.g., You can simply type: "I want a two-bedder with high ceilings and water views in Bondi," and the results will appear).

Fcuking Easy CRM

A featherlight weight CRM system concentrated on sales productivity and built with four core principles in mind:
• Touch-move rule (like in Chess but for communications)
• You need to write down everything (memory is the key)
• Woodpecker sales (write-call-meet till you make it)
• Time only priority
Based on those principles, a salesperson can proceed with several hundred deals simultaneously.


A Ruby on Rails project to schedule appointments.

Originally for USA barbershops network. The point is to adjust the schedule dynamically, depending on the client, if somebody's running late or wants to move earlier. and keep both customers and workers updated.
2011 - 2013

Master's Degree in Physics and Technology

Novosibirsk State University - Novosibirsk, Russia

2007 - 2011

Bachelor's Degree in Physics and Technology

Novosibirsk State University - Novosibirsk, Russia


Gmail API, REST APIs, API Development, Node.js, React, EventMachine, jQuery, Facebook API, Ractive.js, Vue, Twitter API, Pandas, SciPy, Natural Language Toolkit (NLTK)


Git, Adobe Photoshop, Sketch, Sublime Text, WebStorm, Subversion (SVN), NGINX, Bitbucket, Jira


Elixir, JavaScript, ECMAScript (ES6), Python, HTML, GraphQL, CSS, Ruby, Erlang (OTP), TypeScript, SQL, C++


Meteor, Amazon Web Services (AWS), WebSphere MQ, Unix, Geant4, IBM WebSphere, OTP, Ethereum, Visual Studio Code (VS Code)


Model View Controller (MVC), REST, Data Science, Test-driven Development (TDD), Object-oriented Programming (OOP), Search Engine Optimization (SEO), Functional Programming


MongoDB, PostgreSQL, NoSQL, Elasticsearch, Relational Databases, Redis


Material UI, Bootstrap 3+, Phoenix, Ruby on Rails (RoR), OAuth 2, Tailwind CSS, Selenium, AngularJS, Scrapy, React Native


Creative Problem Solving, Customer Relationship Management (CRM), Single-page Applications (SPA), Data Analysis, Minimum Viable Product (MVP), APIs, API Integration, Full-stack, Back-end, OAuth, Startups, Data Scraping, Material Design, Phoenix LiveView, DICOM, LDAP, Natural Language Processing (NLP), Machine Learning, PostgreSQL 9, Discord Bots, Architecture, User Interface (UI), Maps, GPT, Generative Pre-trained Transformers (GPT), Chrome Extensions, Full-stack Development

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