Pavlo Mashchak
Verified Expert in Engineering
Software Engineer and Developer
Orlando, FL, United States
Toptal member since October 14, 2025
Pavlo is a full-stack software engineer with 15+ years of experience building scalable web applications in Ruby on Rails. Skilled in Ruby, JavaScript, TypeScript, React, and Node.js, he works with SQL and NoSQL databases, including PostgreSQL, MySQL, MongoDB, and Elasticsearch. His DevOps expertise spans AWS, Docker, Ansible, and CI/CD. Pavlo delivers clean, maintainable APIs and microservices focused on performance and automation.
Portfolio
Experience
- Ruby on Rails 8 - 15 years
- PostgreSQL - 10 years
- Sidekiq - 10 years
- React - 8 years
- MongoDB - 5 years
- Docker - 4 years
- Python - 3 years
- Node.js - 2 years
Preferred Environment
Python, React, PostgreSQL, MongoDB, Elastic, Ruby, Ruby on Rails (RoR), TypeScript, Supabase, AI Agents
The most amazing...
...work I've done is building a number of applications and services related to CRM and document processing, including complex server compositions.
Work Experience
Full-stack Python/Node.js/React Developer
We Are MRKTNG Inc
- Designed and implemented a FastAPI-based analytics back end processing trading data, exposing async APIs for charts, and reporting pages.
- Built data aggregation pipelines in MongoDB to compute prices, volumes, and aggregation metrics. Reduced client-side processing.
- Created full Dockerized setup, and staging Linux setup instance, using Ubuntu, Nginx, scripting, setup MongoDB services ensuring automatic system restart and failover.
- Developed a React reporting UI with dynamic charts and tables.
Senior Software Engineer
Atkins & Pearce
- Reduced background jobs processing time by optimizing SQL queries, 3rd-party API calls.
- Decreased release cycle by switching to GitFlow, rebuilt the CI/CD pipelines, and implemented SQL schema management.
- Built the CI/CD pipeline with GitHub and Docker. Integrated DataDog agents across the entire infrastructure.
- Architected multi-service applications with the Ruby on Rails stack.
Senior Software Engineer
WebIntegrated LLC
- Built Ruby on Rails website to manage churches and mission members (https://converge.org/).
- Decreased page load speed by integration of Rails Hotwire for UI components.
- Created data structures and models for members table schema.
Senior Software Engineer
Nucleus Healthcare
- Reworked the Ruby back end for the COVID-19 testing platform to support multi-tenancy. Changed authorization and lab results data handling isolation per tenant organization.
- Refactored test scopes to use more flexible libraries like Shoulda, Factories for test suite data sampling bootstrapping.
- Migrated UI modules from legacy jQuery JavaScript framework to React components.
Senior Ruby on Rails Developer
Agari Data Inc
- Built dashboards for vulnerability reports based on SPF, DKIM, and DMARC analysis.
- Extracted portion of email corrections into Python microservices infrastructure.
- Refactored UI logic with Ember views conversion to React.
Senior Software Engineer
Forte Group
- Worked as a consultant for Fortune's top 500 companies in legal software, healthcare, drug development, patient portals, clinical trials, and the sports club memberships industries.
- Created a sequential Ruby handler to process legal document assemblies. Integrated React and Redux components.
- Redesigned plain PHP SQL queries to use the PHP Data Objects (PDO) module.
Senior Software Engineer
Apptopia
- Created ETL scrapers to parse mobile applications metadata.
- Built Ruby scripts to transfer and manipulate data into the Cassandra Data Lake.
- Migrated and refactored page architecture with Backbone Slim views into React components.
Senior Ruby on Rails Developer
Forte Group
- Provided software development consulting services for Fortune 500 companies like Comcast, Xfinity, and AT&T.
- Created authentication Oauth service for AT&T internal store provisioning system.
- Refactored Java callbacks for set top box UI for Comcast – Home Security.
- Designed Ruby API game authentication server for Xfinity Games project.
Senior Ruby on Rails Developer
Helios Technologies
- Developed multiple SaaS startup projects with rapid prototyping and full-cycle development.
- Built product architecture, video conversion module for Ant.com, video and indexing platform.
- Implemented OAuth2 modules and JavaScript SDK for ID.net, authentication and identity platform. Fintech module for secure bank transaction API.
Ruby on Rails Developer
GlobalLogic
- Created an ETL pipeline to move the MySQL database table-by-table data into a new database schema.
- Migrated educational platform from Ruby on Rails 1.2 to version 3.0.
- Created SQL data transition scripts to migrate cross-database data.
Experience
Manufacturing Application
https://www.atkinsandpearce.com/Authentication & Identity Platform
https://www.id.net/Ant.com – Video Conversion & Indexing Platform
Education
Master's Degree in Computer Systems and Networks
Lviv Polytechnic National University - Lviv, Ukraine
Certifications
Python: SOLID Principles and Top Design Patterns
Udemy
MCP Fundamentals for Building AI Agents
Educative
The Complete Python Developer
Udemy
Skills
Libraries/APIs
Sidekiq, Ruby on Rails API, React, GraphQL API, REST APIs, Node.js, jQuery, Backbone.js, Chart.js
Tools
RSpec, Observability Tools, Elastic, Ansible, Git, Splunk, Jenkins, Hotwire, Apache, NGINX
Languages
JavaScript, Ruby, CSS, HTML5, Python, TypeScript, Elixir, SQL, PHP, Java, Java SE (Core Java), GraphQL
Frameworks
Ruby on Rails 6, Ruby on Rails (RoR), Ruby on Rails 5, Ember.js, SPF, Bootstrap, Ruby on Rails 4, Selenium, Vanilla JS, Tailwind CSS, Ruby on Rails 2
Paradigms
REST, Automation, ETL, Prototype-based OOP, Model Context Protocol (MCP)
Platforms
Heroku, AWS IoT, Amazon Web Services (AWS), Docker, Apache Kafka, Linux
Storage
PostgreSQL, MySQL, MongoDB, Microsoft SQL Server, Redis, Datadog, Cassandra, Elasticsearch, Memcached, Data Pipelines
Other
Ruby on Rails 8, Software, APIs, Back-end, Dashboards, CI/CD Pipelines, Full-stack Development, ActiveAdmin, Front-end, Application State Management, Front-end Development, Real-time Data, Electronics, FastAPI, Enterprise Cybersecurity, Cybersecurity Automation, DomainKeys Identified Mail (DKIM), DMARC, Phishing Simulation & Analysis, Ruby Gems, Apache ServiceMix, OOP Designs, SDKs, Authentication, Identity Server, Shell Commands, Artificial Intelligence (AI), API Integration, AI Agents, Patterns, SOLID Principles, Supabase, Back-end Development
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