Vladimir is available for hire
Hire VladimirVladimir Kravchenko
Verified Expert in Engineering
Full-stack Developer
Location
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.
Portfolio
Haven Connect
Elixir, CSS, React, Architecture, JavaScript, SQL, GraphQL, PostgreSQL...
Metalink Labs
Elixir, Phoenix, Vue, PostgreSQL 9.3, Amazon Web Services (AWS), Discord Bots...
Spencer Health Solutions Inc
React, AngularJS, Git, Bitbucket, React Native, Jira, APIs, API Integration...
Experience
Availability
Part-time
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
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 9.3, Amazon Web Services (AWS), Discord Bots, Twitter API, Ethereum, Architecture, APIs, API Integration
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 Developer
2017 - 2019
Palco
- 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
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
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
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
Senior Engineer
2015 - 2015
Sliday
- 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
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++
Experience
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).
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
https://feasy.me/A featherlight weight CRM system concentrated on sales productivity and built with 4 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.
From the technical side:
- AngularJS front-end
- Ruby EventMachine REST API back-end
- PostgreSQL as a database
- Redis for background tasks
- 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.
From the technical side:
- AngularJS front-end
- Ruby EventMachine REST API back-end
- PostgreSQL as a database
- Redis for background tasks
TimeWalla
A Ruby on Rails project to schedule appointments.
Originally for USA barbershops network. The point is to adjust schedule dynamically, depending on client's, if somebody's running late or otherwise want to move earlier. and keep both customers and workers updated.
Originally for USA barbershops network. The point is to adjust schedule dynamically, depending on client's, if somebody's running late or otherwise want to move earlier. and keep both customers and workers updated.
Skills
Languages
Elixir, JavaScript, ECMAScript (ES6), Python, HTML, GraphQL, CSS, Ruby, Erlang (OTP), TypeScript, SQL, C++
Libraries/APIs
Gmail API, REST APIs, Node.js, React, EventMachine, jQuery, Facebook API, Ractive.js, Vue, Twitter API, Pandas, SciPy, Natural Language Toolkit (NLTK)
Paradigms
Model View Controller (MVC), REST, Data Science, Test-driven Development (TDD), Object-oriented Programming (OOP), Search Engine Optimization (SEO), Functional Programming
Platforms
Meteor, Amazon Web Services (AWS), WebSphere MQ, Unix, Geant4, IBM WebSphere, OTP, Ethereum, Visual Studio Code (VS Code)
Other
Creative Problem Solving, Customer Relationship Management (CRM), Single-page Applications (SPA), Data Analysis, Minimum Viable Product (MVP), APIs, API Integration, OAuth, Startups, Data Scraping, Material Design, DICOM, LDAP, Natural Language Processing (NLP), Machine Learning, PostgreSQL 9.3, Discord Bots, Architecture, User Interface (UI), Maps, GPT, Generative Pre-trained Transformers (GPT)
Frameworks
MUI (Material UI), Bootstrap 3+, Phoenix, Ruby on Rails (RoR), OAuth 2, Selenium, AngularJS, Scrapy, React Native
Tools
Git, Adobe Photoshop, Sketch, Sublime Text, WebStorm, Subversion (SVN), NGINX, Bitbucket, Jira
Storage
MongoDB, PostgreSQL, NoSQL, Elasticsearch, Relational Databases
Education
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