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Marcos Yu

@marcosyu

Message

I build scalable Ruby on Rails applications, APIs, and event-driven systems.

Philippines

Message

I've built scalable web applications for Acima, First Circle, Nevaya, and Cognizant using Ruby on Rails, PostgreSQL, React, and modern API architectures.

At Acima, I designed high-throughput Sidekiq pipelines, implemented Elasticsearch search, integrated Plaid, and helped refactor event-driven systems with Kafka and AWS SQS. I also modernized legacy CoffeeScript and AJAX codebases with StimulusJS.

At First Circle, I delivered revenue-critical origination features, REST and GraphQL APIs, and responsive React and TypeScript components. I also built an AI-driven document identification workflow using TensorFlow.

I lead code reviews, mentor engineers on coding standards, investigate production issues, and improve documentation and onboarding. I care about reliable, maintainable, high-performance systems that help distributed teams ship production-ready features.

Experience

Work history, roles, and key accomplishments

Current

Sr. Software Engineer B3

Current

Cognizant

May 2026 - Present (4 months)

Building features and optimizing performance of the web application. Leading and mentoring on coding standards and best practices, performing code reviews, developing AI automations, and providing application support.

Ruby on Rails AI Automation Code Review Mentorship Application Support

Sr. Software Engineer

Acima

Feb 2022 - Mar 2026 (4 years 1 month)

Focused on scalable backend systems, performance optimization, and continuous improvement of engineering workflows. Leveraged GitHub Copilot, designed high-throughput background job pipelines with Sidekiq, implemented Elasticsearch-based search, integrated Plaid, led frontend modernization, and contributed to system design and mentoring.

Ruby on Rails PostgreSQL AnyCable Flipper StimulusJS React GrapeAPI Next.js GitHub Co Pilot Sidekiq Elasticsearch Plaid Kafka AWS SQS Event Driven Architecture System Design Mentorship

Product Engineer

First Circle

Sep 2019 - Jul 2022 (2 years 10 months)

Delivered revenue-critical origination features, designed and implemented API endpoints (REST/GraphQL), developed responsive frontend components using ReactJS and TypeScript, integrated AWS Cognito and S3, and built an AI-driven document identification system using TensorFlow.

Ruby on Rails React TypeScript Webflow Docker GraphQL TensorFlow Amazon Cognito S3 REST APIs

Ruby on Rails Developer

Nevaya Ltd.

Oct 2016 - Jun 2019 (2 years 8 months)

Maintained six web applications, worked closely with the UK team on new features and APIs, integrated AWS Cognito for SSO, added role-based access, integrated scheduled email notifications, added Intercom, and implemented internationalization for multi-language support.

Ruby on Rails React AJAX Amazon Cognito S3 Elasticsearch PostgreSQL Shoryuken Clockwork Sendgrid Intercom Internationalization

Ruby on Rails Developer

Studio RailsWay

Sep 2016 - Oct 2016 (1 month)

Created a collaborative document editor, added ownership and document locking, implemented role-based access, and implemented autosaving and caching.

Ruby on Rails EmberJs CoffeeScript AJAX jQuery

Ruby on Rails Developer

Crown Agents

Nov 2013 - Sep 2016 (2 years 10 months)

Implemented a new responsive UI using Bootstrap for Guyana Revenue Authority, worked with dynamic fields using liquid form, implemented AJAX validations, implemented email notifications with liquid templates, and added role-based access levels.

Ruby on Rails CoffeeScript AJAX jQuery SASS Bootstrap Liquid Templating