Dennis Martinez

I build, optimize, deploy and scale web applications

My name is Dennis Martinez, and I currently reside in Osaka, Japan. I've been working at startups for the past 10 years, mostly doing web development with Ruby on Rails and Javascript.

As of June 2015, I'm no longer accepting requests for contract work. However, feel free to contact me for anything related to my projects.



1998 - 2003

Universidad Interamericana de Puerto Rico - Ponce

Bachelor of Science in Computer Science, graduated Magna Cum Laude, included in Dean’s List from 2000 to 2003



Able / Software Engineer

Working on partner and studio web application projects.

October 2014 - June 2015

Self-employed / Freelancer

Helping individuals and companies create web applications, fix misbehaving applications, and scale growing applications.

June 2013 - October 2014

Storenvy / Software Engineer

Responsible for the backend functionality of the main website and partner APIs using Ruby on Rails and assisting DevOps team with server administration.

February 2010 - June 2013

RepairPal, Inc. / Senior Software Engineer

Responsible for the backend functionality of the website, mobile apps and partner APIs using Ruby on Rails.

January 2008 - January 2010

JPM Global, Inc. / Software Engineer

One of the lead developers for BarterQuest, responsible for many of the application’s early architectural decisions using Ruby on Rails.

January 2004 - January 2008

Nova Terra Recycling / IT Supervisor & Software Engineer

In charge of developing and supervising all IT projects, developing web administration interfaces in PHP for ecommerce sites with integrated access to eBay.


Ruby & Ruby on Rails - 90%

HTML & CSS - 70%

Javascript 60%

Server Administration - 80%

Some of the tools I use

  • Ruby
  • Ruby on Rails
  • Linux
  • Sinatra
  • RSpec
  • Bootstrap
  • jQuery
  • Git
  • PostgreSQL
  • Elasticsearch
  • Redis
  • Memcached
  • Vagrant
  • Amazon S3
  • DigitalOcean


  • All
  • Startups / Other
  • Mobile
  • Open Source

Echo For Trello

January 2015

Work done:

  • Built entire application from scratch.
  • Used OAuth for authentication with Trello.
  • Used Sidekiq for setting up recurring tasks and handle failures automatically.
  • Used Cron to trigger background tasks.

Tools used:

  • Ruby 2.2.0
  • Ruby on Rails 4.2
  • PostgresSQL
  • Sidekiq
  • Linux (Ubuntu)
  • Nginx HTTP Server
  • Phusion Passenger
  • Redis
  • Sidekiq
  • OAuth (connectivity to Trello)


June 2013 to October 2014

Work done:

  • Upgraded the entire application from Ruby on Rails 3.1 / Ruby 1.9.3 to Rails 3.2 / Ruby 2.0, and prepared the application to upgrade to Rails 4.0 / Ruby 2.1.
  • Replaced the entire search architecture by replacing a single Sphinx instance with a three-node Elasticsearch cluster for reliability and scalability, and porting and refactoring our current search code.
  • Assisted with refactoring the six-year codebase by beginning to split functionality into separate, individual services using Rails engines.
  • Helped integrate Google Places API to help users select their address easily.
  • Helped integrate Stripe API (Stripe Connect / Stripe Checkout).
  • Implemented more rigid testing requirements with other engineers by requiring tests for any new functionality.
  • Assisted remote DevOps team with server-related issues for our staging and production environments.

Tools used:

  • Ruby 1.9.3 and 2.0
  • Ruby on Rails 3.1 and 3.2
  • MariaDB / Galera Cluster
  • Elasticsearch
  • Linux (Ubuntu)
  • Apache HTTP Server
  • Phusion Passenger Enterprise
  • Redis
  • Resque
  • Memcached
  • Stripe API
  • Google Places API
  • AWS (S3, Cloudfront, Redshift)

WaniKani to Anki Exporter

April 2014

Work done:

  • Built from scratch and open-sourced for the WaniKani community.
  • Used two Ruby gems created by myself: wanikani for WaniKani API connectivity, and anki for Anki deck generation.
  • Using caching for performance purposes and to avoid constantly calling the external API.

Tools used:

  • Padrino Framework
  • WaniKani API
  • Memcached
  • Twitter Bootstrap
  • Digital Ocean
  • Nginx


February 2010 to June 2013

Work done:

  • Upgraded the entire application from Ruby on Rails 2.3 / Ruby 1.8.7 to Rails 3.2 / Ruby 1.9.3.
  • Helped automate building the entire architecture for RepairPal's car repair estimator tool, using industry-standard data from multiple automotive association leaders (AAIA, MOTOR, Mitchell, etc.).
  • Built systems for daily reporting and metrics for the product team.
  • Built tools using Twilio's API to automatically provision phone numbers for new auto repair shops entered in our system.
  • Help build auto repair shop portal section to track phone calls made from provisioned Twilio phone numbers and provided easy access to call recordings.
  • Suggested and implemented code reviews between developers using GitHub pull requests.
  • Implemented more rigid testing requirements by requiring tests for any new functionality.

Tools used:

  • Ruby 1.9.3
  • Ruby on Rails 2.3 up to Ruby on Rails 3.2
  • MySQL
  • Sphinx
  • Delayed Jobs
  • Linux (Gentoo)
  • Nginx
  • Memcached
  • Twilio API
  • AWS (S3, Cloudfront)

RepairPal - iOS and Android apps

October 2011 (iOS) / November 2011 (Android)

Work done:

  • Helped build the front-end components using HTML5 and the Backbone.js framework.
  • Helped add / modify the RepairPal API for connectivity between the mobile application and the server.
  • Helped debug both iOS and Android apps on multiple devices.

Tools used:

  • Backbone.js
  • jQT
  • iOS 5 / 6
  • Android 2.x


January 2008 to January 2010

Work done:

  • Set up multi-stage deployment strategy with Capistrano for our site testing and production deployment needs.
  • Helped implement unit, functional and integration testing practices using Ruby’s Test::Unit library, as well as Cucumber / Webrat.
  • Implemented and maintained various servers for development, testing and production purposes, including web and database servers.
  • Integrated APIs from external sites, such as Twitter and PayPal.
  • Handled customer support inquiries via email and online help desk.

Tools used:

  • Ruby 1.8.7
  • Ruby on Rails 2.3
  • MySQL
  • Sphinx
  • Delayed Jobs
  • Linux (OpenSUSE)
  • Apache HTTP Server
  • Phusion Passenger
  • AWS (S3, EC2, Cloudfront)
  • PayPal API


Location: Osaka, Japan