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John Haig
Verified Expert in Engineering
Full-stack Engineer and Software Developer
Denver, CO, United States
Toptal member since December 11, 2025
Bio
John is an award-winning software architect and full-stack engineer with over 30 years of experience, directing teams to a Webby and four MAXI Awards. John is an expert in Ruby on Rails, Node.js, microservices, and enterprise SaaS, and the author of the CCCUX and MegaBar Rails gems. As an early adopter of AI pair programming, he has a proven track record of delivering innovative solutions in finance, healthcare, and retail.
Portfolio
Wonkx
Node.js, Shopify, Mindbody API, eCommerce, AI Driven Ecommerce, PostgreSQL...
Merge
Ruby, Ruby Gems, React, PostgreSQL, Node.js, AWS Lambda, Java, Spring...
Bluemoon Digital
Ruby, Ruby Gems, React, PostgreSQL, RSpec, Capybara, factorybot, Selenium, VCR...
Experience
- Web Development - 20 years
- REST APIs - 14 years
- Git - 14 years
- Ruby Gems - 12 years
- Node.js - 12 years
- Ruby - 12 years
- PostgreSQL - 12 years
- Ruby on Rails 8 - 2 years
Preferred Environment
APIs, Ruby, Node.js, Java, OS X
The most amazing...
...achievements include winning a Webby Award for the best health website, receiving four MAXI Awards, and being the fourth employee at the first web agency.
Work Experience
Full-stack Contractor
2025 - PRESENT
Wonkx
- Architected and implemented comprehensive security hardening across a PERN (PostgreSQL, Express, React, and Node.js) microservices platform, including JWT-based authentication and a robust audit logging system.
- Designed and developed a full Stripe Connect integration, handling platform charges, application fees, and international currency processing, resulting in seamless multi-currency payment processing.
- Introduced idempotency for financial operations and executed a 56-step security hardening plan with automated testing, eliminating duplicate transactions and boosting system reliability.
- Developed a database-driven role-based access control (RBAC) system with dynamic permissions and a React admin interface, providing fine-grained access control across adaptable role definitions.
- Built a TypeScript agentic commerce platform (ACP) adapter microservice allowing AI agents to autonomously initiate payment sessions with HMAC authentication, nonce-based replay protection, and detailed event logging.
- Integrated OpenAI and Perplexity LLMs to power a commerce agent enabling natural language product discovery, session creation, and payment processing with configurable guardrails and dry-run modes.
- Deployed Shopify webhook integration for universal product catalog synchronization, enabling multi-source product feeds and real-time inventory updates across eCommerce platforms.
- Implemented a full-stack application to Azure Container Apps with PostgreSQL, Redis, and Key Vault, orchestrating four containerized microservices with managed identities and secure secret management.
- Established a comprehensive test automation strategy across all services using Vitest, achieving over 640 passing tests with enhanced database mocking patterns and test data factories for maintainable, reliable test coverage.
- Built advanced CSV export functionality with enhanced queries, including payment method details, actor information, and correlation IDs, supporting business intelligence and compliance requirements with 50,000 record export limits.
Technologies: Node.js, Shopify, Mindbody API, eCommerce, AI Driven Ecommerce, PostgreSQL, Cursor AI, Enterprise, IT Security, Enterprise SaaS, Docker, Azure, Azure CLI
Senior Software Architect
2021 - 2025
Merge
- Directed an eight-person engineering team, establishing Ruby coding standards and Rails best practices for a multi-tenant SaaS platform with PostgreSQL, Ruby on Rails, and React, improving code quality and reducing technical debt.
- Built integrations between Salesforce Commerce Cloud and AWS Lambda using Node.js and Ruby scripts, enabling seamless real-time order synchronization across platforms.
- Architected Workato automation to synchronize marketing campaign data across Salesforce, Monday, and Asana via Marketo triggers, streamlining workflows and maintaining real-time data consistency.
- Drove the development of a Java Playframework application with Marketo API integration, delivering automated marketing campaign capabilities for enterprise clients.
- Engineered and implemented enterprise integrations connecting advertising platforms, CRM systems, and project management tools for streamlined workflow automation.
Technologies: Ruby, Ruby Gems, React, PostgreSQL, Node.js, AWS Lambda, Java, Spring, playframework, Scala, APIs, Workato, Salesforce, Marketo, Monday.com, Asana, API Integration, Team Leadership, Microservices, Enterprise SaaS, Heroku, Git, GitHub, GitHub CLI
Senior Full-stack Engineer
2019 - 2021
Bluemoon Digital
- Built a multi-tenant SaaS platform with Ruby on Rails, React, and PostgreSQL, enhancing analytics for major advertising clients and improving campaign ROI visibility.
- Implemented comprehensive test coverage with RSpec, Factory Bot, Capybara, Selenium, and VCR for external API mocking, achieving over 95% code coverage and reducing production bugs.
- Developed analytics features and reporting tools, enhancing campaign ROI visibility for enterprise advertising clients.
- Architected scalable multi-tenant infrastructure supporting multiple advertising clients with isolated data and custom configurations.
Technologies: Ruby, Ruby Gems, React, PostgreSQL, RSpec, Capybara, factorybot, Selenium, VCR, Material UI, Software as a Service (SaaS), APIs, Testing, Responsive UI, Enterprise SaaS
Engineering Manager for Site Reliability and Production Support
2016 - 2019
Cognizant
- Enhanced system performance and usability by developing large-scale financial applications in Ruby for Oppenheimer Funds.
- Managed and mentored 12-person onshore and offshore engineering teams, boosting productivity and collaboration.
- Resolved over 2,500 production incidents and fixed more than 500 bugs, enhancing system reliability.
- Wrote test coverage in RSpec for hundreds of model, controller, service, and concern files, ensuring code quality.
- Optimized the Jenkins and AWS continuous integration environment, improving deployment speed and system stability.
Technologies: Computer Programming, Reliability, Testing, RSpec, Splunk, Ruby, Ruby Gems, PostgreSQL, MongoDB, Jenkins, Continuous Deployment, Incident Management
Senior Software Engineer
2016 - 2017
Travelers Haven
- Added key functionality to Ruby on Rails and Angular applications, optimizing booking flow and elevating user experience.
- Utilized GitFlow versioning and CircleCI on Heroku, enabling continuous integration and reducing deployment time.
- Released Salesforce ETL integration with the Restforce gem and Apex, automating customer data synchronization.
- Refactored error and cancellation handling for the hotel booking site, reducing booking failures and improving customer satisfaction.
- Implemented Active Job with Sidekiq for delayed jobs, ensuring reliable background processing for email notifications and reporting.
Technologies: Ruby, Ruby on Rails 6, RSpec, Angular, Git, GitHub, CircleCI, Heroku, Salesforce, Restforce, APEX Code, ETL, Active Jobs, Redis, Sidekiq, Background Jobs, Continuous Deployment, API Integration
Director of Web Development
2008 - 2016
Placewise Media
- Developed and launched an MVC social platform for 350 major market shopping mall sites, creating a unified digital presence.
- Grew platform from zero to over 500,000 users, implementing scalable architecture and performance optimization.
- Won four MAXI awards for interactive programs distributed across multiple mall websites, including holiday campaigns and loyalty programs.
- Delivered a Santa reservation system in Rails with RSpec, and with Node.js and Grunt, establishing modern development practices.
- Built secure REST JSON APIs and web services, enabling 3rd-party integrations and mobile applications.
Technologies: Ruby, Ruby on Rails 6, RSpec, Node.js, Grunt, REST, REST APIs, JSON, PHP MVC, PHP, JavaScript, jQuery, Social Media Apps, Architecture, Optimization, SOAP, CSS
Application Developer
2006 - 2008
Catapult Technologies
- Programmed Java servlets and JavaServer Pages (JSP) with Hibernate for a federal government client, delivering secure document management systems.
- Architected a form builder and handler application in ColdFusion with Oracle, streamlining government data collection processes.
- Engineered enterprise applications for federal government clients, ensuring security compliance and system reliability.
Technologies: Computer Programming, Java
Webmaster
2005 - 2005
New Orleans Hospitality
- Managed bigeasy.com and 11 additional tourism websites, maintaining content and technical infrastructure.
- Built Yahoo Store using RTML for bigeasy.com, enabling eCommerce capabilities for local tourism products.
- Maintained and updated website content and technical infrastructure for a major New Orleans tourism destination.
Technologies: Computer Programming, Web Development
Consultant
2003 - 2003
State of Louisiana
- Installed and configured a multitier IBM WebSphere portal cluster for the State of Louisiana, establishing enterprise portal infrastructure.
- Designed and implemented an enterprise portal architecture to support state government operations and citizen services.
- Established scalable infrastructure for multitier portal deployment, ensuring high availability and system reliability.
Technologies: Computer Programming, System Architecture, IBM WebSphere
Director of Web Development
1998 - 2002
Oxygen Media
- Hired and directed engineering staff of more than 15 developers and designers, building a high-performing team.
- Developed and coded dozens of health-related web content programs, establishing Oxygen as a leading women's health destination.
- Received Webby Awards in Health in 2000 and 2001 for outstanding health content and user experience.
Technologies: Computer Programming, Web Development, Management
Project Manager
1994 - 1997
Organic Onlin
- Joined as employee number four at the first web development agency, helping establish industry best practices for modern web development.
- Coded and produced original web projects using HTML, computer-generated imagery (CGI), and early web technologies for Fortune 500 clients.
- Managed cross-functional teams of clients, contractors, engineers, and account managers, delivering projects for Saturn Cars, Volvo, Johns Hopkins, Aetna, and McDonald's.
Technologies: Computer Programming, Web, Web Project Management
Biological Technician
1991 - 1994
US Fish and Wildlife Service
- Surveyed, tagged, and conserved wildlife habitats and populations across regions from Mexico to Maine.
- Oversaw volunteer teams supporting field research and data collection operations.
- Conducted data entry and statistical analysis, with results published in peer-reviewed journals.
Technologies: Computer Programming, Excel 2010
Audiovisual (AV) Coordinator
1988 - 1988
Harvard University
- Managed audiovisual equipment for classroom recordings.
- Recorded business courses using professional audiovisual equipment.
- Analyzed data sets and business metrics using Microsoft Excel to support decision-making.
Technologies: Computer Programming
Experience
The Band Plan
https://thebandplan.com/I founded and drove the development of The Band Plan. This complete band management platform enables musicians to manage albums, electronic press kit (EPK) releases, live recordings, gig opportunities, networking, and collaborative setlists. I designed it as an all-in-one solution for working musicians.
CCCUX Role Management Ruby Gem
https://rubygems.org/gems/cccuxI founded and developed CanCanCan Admin, a comprehensive admin interface and UX layer for Rails authorization. I implemented role-based access control with a unified ownership system, seamless Rails integration, custom authorization patterns, and flexible permission management.
MegaBar Enterprise Engine
I founded and developed Megabar.net, an enterprise Rails engine that converts form-based configuration into full web applications. I implemented dynamic model generation, automatic CRUD interfaces, block-based layout management, and multi-tenant support, along with a deterministic ID system to prevent seed conflicts, CCCUX authorization integration, context-aware field formatting, and zero-configuration setup with automatic RSpec test generation.
Microservices Architecture
I designed an event-driven microservices architecture featuring a Rails order publisher, Amazon SNS and SQS messaging, and multiple subscriber services that handle email, inventory, and analytics. I also deployed using Terraform, Docker, and Kubernetes on Amazon Elastic Kubernetes Service (EKS), featuring autoscaling, health checks, service discovery, and CloudWatch monitoring.
Bagus.org
https://www.bagus.org/I built a JSP/MySQL non-MVC CMS in 1996, still running on bagus.org, that organizes content across three interdependent navigation dimensions. I designed each content area to support unique navigation structures, allowing content to move between areas while maintaining flexible, cascading designs that can be overridden at lower levels. Items appear at intersections of any dimension combination, enabling highly flexible content organization.
Education
1984 - 1989
Bachelor of Science Degree in History of Science
University of Wisconsin - Madison, WI, USA
Certifications
MAY 2025 - MAY 2027
Workato Pro 3
Workato
Skills
Libraries/APIs
React, Node.js, jQuery, REST APIs, Sidekiq, Mindbody API, Backbone.js
Tools
RSpec, Splunk, Jenkins, VCR, Front-end Build Tools, Git, GitHub, GitHub CLI, CircleCI, Asana, Terraform, Grunt, Jspx, Excel 2010
Languages
Java, Ruby, JavaScript, PHP, CSS, HTML, Scala, CoffeeScript, APEX Code, Dart, Objective-C
Frameworks
Capybara, Selenium, Material UI, Play Framework, Angular 2, Bootstrap, Ruby on Rails 6, PHP MVC, Angular, Spring, Spring 6, Ember.js
Paradigms
Management, Testing, Continuous Deployment, Microservices, REST, ETL
Platforms
Web, Workato, Marketo, Amazon Web Services (AWS), Docker, Software Design Patterns, Eclipse, OS X, Heroku, IBM WebSphere, AWS Lambda, Salesforce, Kubernetes, Shopify, Azure
Storage
PostgreSQL, Data Integration, Database Integration, JSON, Redis, MySQL, MongoDB
Other
Computer Programming, Web Project Management, Web Development, System Architecture, Reliability, Ruby Gems, Incident Management, factorybot, Software as a Service (SaaS), APIs, Responsive UI, playframework, API Integration, Team Leadership, AI Assistants, Middleware, Engines, Custom CMS Development, Cursor AI, Enterprise Error Handling & Optimization, Recipe Lifecycle Management, Full-stack, Software Architecture, Ruby on Rails 8, Chrome DevTools, Front-end Design, Enterprise, Enterprise SaaS, Social Media Apps, Architecture, Optimization, Restforce, Active Jobs, Background Jobs, Data Transformation, Monday.com, Pub/Sub, Cloud Pub/Sub, eCommerce, AI Driven Ecommerce, Mobile App Development, Regular Expressions, IT Security, Azure CLI, SOAP, TinyMCE, iOS App Development, R Programming
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