Marko Kallas
Software Developer
9+ years exp
JavaScript
Ruby
SQL
TypeScript
Active 2 days ago
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Overview
Technical skills
Timeline
Roles
Overview
Software engineer with about 9 years of experience building and maintaining marketplace platforms and scalable web applications. Works across backend and frontend, with hands-on experience in Ruby on Rails, PostgreSQL, React, and TypeScript, plus unit and integration testing using RSpec and Jest. Frequently contributes to system performance through query optimization and data modeling, and supports delivery through mentoring and code review.
Technical skills
JavaScript
Ruby
SQL
TypeScript• Senior • 5y+
Ruby
RSpec• 9y+
Ruby on Rails• 9y+
Sidekiq• 5y+
Databases
PostgreSQL• 9y+
Redis• 5y+
Frontend
Redux
React.js• 9y+
Mobile
State Management
DevOps
Rest API
CircleCI• 9y+
Git• 9y+
Docker• 5y+
QA
Jest
Timeline
Senior Software Engineer, Marketplace
•
Senior
IBM
•
Full-Time
Led design and architecture for new marketplace features on a two-sided platform connecting customers and vendors. Built and maintained full-stack functionality with Ruby on Rails, React, TypeScript, and PostgreSQL, including query optimization and data modeling improvements. Mentored engineers through reviews and testing best practices, and led an end-to-end payment integration from requirements to deployment while coordinating with external API providers.
Ruby on Rails
React.js
TypeScript
PostgreSQL
RSpec
Jest
Git
Docker
Senior Software Engineer, Marketplace
•
Senior
Microsoft
•
Full-Time
Developed and maintained RESTful APIs for a large-scale marketplace using Ruby on Rails and PostgreSQL, focusing on low latency and high throughput. Partnered with frontend engineers to integrate React interfaces, and improved reliability by expanding RSpec-based unit and integration testing. Optimized SQL with indexing strategies, introduced background job processing for async work, and led migration of legacy services toward a modular architecture.
Ruby on Rails
PostgreSQL
React.js
TypeScriptsince 2021
RSpec
Sidekiq
Redis
Dockersince 2021
Software Engineer, Marketplace
•
Middle
Adobe
•
Full-Time
Implemented features for a web-based marketplace platform using Ruby on Rails and PostgreSQL to support transactions and user management. Worked with product and design teams to translate requirements into technical specifications and responsive React components. Added RSpec unit tests for maintainability, performed database tuning and migrations, and supported production issue triage and remediation to maintain service availability.
Ruby on Railssince 2017
PostgreSQLsince 2017
React.jssince 2017
RSpecsince 2017
Gitsince 2017
CircleCI
San José State University
Bachelor's Degree •
Computer Science