Marcus Derencius
[email protected] | twitter @derencius | github @derencius | linkedin marcusderencius


I'm a senior web developer with experience as team leader, consultant and code mentor.

I have solid knowledge of analysis and design of relational and graph database using PostgreSQL and neo4j, architecting ruby on rails applications, building servers for deployment and implementing rich user interfaces using tools like coffescript/es6, scss and react.

My Skills

  • 7 years of experience building Ruby on Rails.
  • Applications setup, maintenance and optimization.
  • Implementing rich UI using React, Coffeescript/ES6 and structured CSS.
  • Designing and optimizing PostgreSQL Databases.
  • Design and integrate graph database using neo4j.
  • Software Development Estimation (I was a certified Function Point Analyst).
  • Server Administration, mostly heroku and aws recently.
  • Advanced Git.

My Career

Nov, 2013 - Sep, 2015 Senior Rails Developer @ The Starter League, Chicago

At Starter League my main responsibility was to build and keep running LanternHQ. Lantern is a simple LMS built using rails and PostgreSQL. The key features I built were:

  • Payment Integration with Stripe. I built the payment processing part, where teachers could be able to pay the app's fee for its students, or students could have the option to pay their own fees.
  • Discussions via email. Trying to mimic a group discussion via email, each classroom had an unique email address that any message sent by its members would create a new discussion in the app.
  • Performance optimizations. Suddenly a teacher could start using the app in the classroom where 20 to 200 students could start using the app at same time. An extensive optimization of database queries and indices, caching using russian doll caching, and memory optimization were done. We could even reduce the number of heroku dynos in use.
  • Redactor RTE Integration. Redactor is a powerful rte editor, but still a deep integration with existing classroom assets and s3 async processing were necessary.

A secondary responsibility was to mentor students from the Starter School program. Those students were taking a nine months long course to learn how to build their own applications. Mostly were rails based, and I paired and mentored with them in the class room, or remotely using hipchat and via pull-requests.

Sep, 2009 - Sep, 2015 Rails Develoepr @ Independent Contractor

As a Ruby on Rails contractor, I had the chance to build various applications. From small to large ones, and keep them running for a good time.

Some of the companies and projects I built apps for:

Canção Nova - Cachoeira Paulista, BR

One of largest catholic communities and TV station in Brazil. For those projects I leaded a team of four other developers.

  • Canção Nova CRM. One of largest rails app I've build. It handles more than one million of people, and has integration with banks and 3rd party vendors. Also a massive data migration from the old system was made. It provides a JSON API for the associates portal.
  • Loja Canção Nova. This is a complex ecommerce application, custom built to fit their needs. It handles sales for final customers, door-to-door representatives, via call center, and wholesale between branches. It has deep integration with the CRM, and the corporate ERP using Oracle APIs.
  • Associates Portal. This application allowed donators to manage their personal info, perform new donations using online payments. It integrates with the CRM application using a JSON API.

NoxxonSat - São Paulo, BR

NoxxonSat builds vehicle tracking devices, used mostly by buses and trucks. The information of those devices are available via APIs and via a web application, used by their clients and the public transit agencies.

For them I built a couple of applications:

  • OCOP: Application to track occurrences by public transit providers, where all accidents or delays must be reported. This is a rails application using PostgreSQL and wkhtmlpdf to generate pdf.
  • Gestec: An integration application, that connects various APIs to collect and serve routes, vehicles, timetables for the ecosystem. This is a rails and PostgreSQL based application. It also provide a JSON API.
  • NXControl: This application allows transit companies to manage their fleet of buses, including service scheduling, fueling records and drivers schedule.
  • NXWeb: Individuals that have the tracking devices installed on their vehicles, can monitor in almost real time their vehicles and perform actions like remote locking, send message and generate reports of position history. This is a rails application, using PostgreSQL, react js, google maps integration and a JSON API.
  • NXweb2: A rewrite of the first application, using Rails/React/ES6 and various asynchronous jobs.
  • NxGD and E3 Driver: A sockets based ruby application to send/receive connections for a 3rd tracking device for motorcycles, using threads to handle hundreds of devices connected. This application connected to the Nxweb2 using a JSON API.

Casven - London, UK

For this british startup I built the first version on their product, an application that aims to map many companies around the world, that can interest financial investors. It would monitor companies products and finances.

A key challenge with this application was to design the graph database mapping companies, markets, financial data and products.

Sep, 2007 - Sep, 2009 Rails Developer @ Surgeworks LLC - Salt Lake City, Utah

I joined Surgeworks to work as a Rails Developer, and ended up as team leader of a group of five developers.

My key challenges working there were to build and keep the team, communicate and negotiate with clients, write various rails applications, setup servers for deployment, share knowledge regarding technical practices.

Fev, 2007 - Jul, 2007 Function Point Analyst @ Tata Consulting Services - São Paulo

As a Certified Function Point Practitioner I estimated and coordinated the estimated of various software projects, elaborated commercial and financial proposals, and discussed the estimated features with clients.