About Simon Rentzke

Experienced in systems architecture, business analysis, devops and managing lean teams.

Has more than 15 years of programming experience.

Personal Details

  • Mobile: +61449793553
  • Email: simon@rentzke.com
  • @sren
  • github
  • quora
  • goodreads
  • last.fm
  • stack overflow
  • kiva
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  • Skills

    Ruby and Rails – I have been using Ruby since 2006. I have a good knowledge of the Rails framework and have extensive experience with many of the popular Ruby gems.

    Javascript - I have been using Javascript for a number of years, and although not an expert front end developer, I have a working knowledge with Node.js, and some front end frameworks such as React, Vue.js, AngularJS and Backbone.

    HTML & CSS – I have helped with the UI on a number of projects, and am very confident with HTML and CSS.

    Mobile development - I have built a few mobile specific websites and apps using a combination of tools.

    Kanban & Scrum – I have worked both individually and in teams ranging in size from 2-20 people. I have a proficient understanding of the Agile process (specifically using Scrum), and am comfortable applying it to projects I work on.

    Databases – I have been using Postgresql and MySQL for over 10 years, and am comfortable both with using and administering them. I am confident user of Redis, ElasticSearch, MongoDB, Google BigQuery and Amazon's Redshift. I also have some experience using document oriented databases such as DynamoDB, MongoDB and CouchDB.

    Devops - I am a confident user of AWS and Google Cloud Services, and take an active interest in Docker, as well as Kubernetes.

    Operating Systems – I am comfortable with Linux-based servers. I primarily use Mac OS X as my development OS, but also have experience with Ubuntu.

    SCMs – I have been using Git for a number of years and am a confident user. I also have experience with Subversion.


    Business Development - Experienced with estimations, contract negotiation, client relationships.

    Marketing/Sales - Helped with the marketing and sales strategy of Unboxed Consulting.

    Finance - I have experience managing cash flow and and keeping the accounts in order.

    Recruitment - I have interviewed over 100 people, and helped build great development teams.

    Growth & Strategy - I have helped with and taken a keen interest in strategic goals and growth decisions.

    Kinda excited about:


    Lean teams

    Renewable Energy

    Electric Cars

    Machine Learning

    Latest Experience

    Director of Engineering, Intellum (Nov 2017 - Current)

    Part of a little team that produces a sweet little product that millions of users use to improve their work and knowledge.

    Software Engineer, Intellum (Nov 2011 - Nov 2017)

    Worked predominantly on Intellum's flagship product exceedLMS. I was responsible for introducing a test suite and upgrading the entire app from Rails 2, to Rails 3, and Ruby 1.8, to 1.9.3 to 2.1.3. This included updating gems, and refactoring the codebase. I also introduced Sidekiq which helped stabilize and scale the background workers. Other achievements included; Zencoder, GoToMeeting and Webex integrations; keeping the application stable with hockey stick growth, a state driven mobile application built with JavaScript, 45% improvement in application response time through PostgreSQL optimization.

    Agile Mentor/Team Lead, NetEngine.com.au (Jan 2011 - Nov 2011)

    Tightened up the development process of key projects. Introduced continuous integration, and a healthy test driven ethos. Managed clients expectations and delivered weekly deploys. Balanced clients urgent requirements for 4 key projects with limited resources.

    Software Engineer, five.tv (3 sprints 2010)

    Pair programmed, mentored developers and taught our BDD development process and principles. We built the new Five.tv(now Channel5) on demand website Five.tv.

    Operations Manager, Unboxed Consulting Cape Town (8 Months, 2010)

    Unboxed opened up a new office in Cape Town. I helped build a happy development team. Managed the accounts and finance. Was also responsible for business development and marketing. Built some great quality apps for a few clients.

    Software Engineer, berglondon.co.uk (2 weeks 2009/2010)

    Worked on a very tight timeline. Built a ruby project to parse InDesign IDML files into BERG London's MIB templating engine for their iPad application for Popular Science Magplus.

    Software Engineer, MadebyMany.com (1.5 years 2009/2010)

    Worked with a team of top class dudes, we built vinspired.

    Software Engineer, MadebyMany.com (5 months 2009)

    Was involved in a small exploratory project for Bartle Bogle Hegarty. Involved tracking large data sets, mainly from Twitter, Youtube, Google, blogs and Flickr. The data was then aggregated into useful information, allowing BBH to both use it as a metric against their campaigns and also explore their brands presence and trends within social media.

    Software Engineer, Agency.com (3 months 2008/2009)

    Lead analyst/developer of Great Britons. A talent search initiative from British Airways for the buildup to the 2012 Olympics. The site was built with Ruby on Rails 2.2.2 and included a full Rspec test suite. Featured included video upload with the YouTube API, Facebook Connect, moderation and a profanity filter.

    Software Engineer, British Airways metrotwin.com (6 months 2008)

    Lead developer of Metrotwin, a rich content social media site. Responsible for systems design and development. Built with Ruby on Rails 2.1 in an agile TDD environment using Scrum. Responsible for 94% test coverage using RSpec. System featured RESTful routing, Google Maps integration, social community, JQuery plugins and Amazon S3.

    Software Engineer, Tipped (11 months 2007/2008)

    Responsible for systems design and development of a social networking site, Tipped. Responsible for driving development sprints and fortnightly deployments. Also responsible for communication with product owner and developers in a distributed team. Built in an agile BDD environment using Ruby on Rails 2.0. Key responsibilities included: SMS integration, social networking, Google and Yahoo! map integration, performance enhancements, a full test suite in Test::Unit, SEO and a mobile front end. Also built a keyword based adserver.

    Software Engineer, Public Health Knowledge Network (1 month 2008)

    Analyst/Developer in an agile environment on phkn.org using Ruby on Rails 2.1, introduced mass personalised mailing updates, enhanced group work flows, increased test coverage and enhanced performance.

    Ruby on Rails Auditor/Consultant, OSC Consulting (3 months 2007)

    Consultant for an NHS Ruby on Rails system. Responsible for ensuring rails best practice was used, performance tuning, new release prioritisation and systems design.

    Software Engineer, Osgood (3 months 2006/2007)

    Worked with a small team to build Osgood Textiles an e-commerce B2B textile shop using Ruby on Rails 1.2.3. Included credit card payment, shopping cart, product, customer and order management.

    Software Engineer, Quickerbox (7 months 2006/2007)

    Designed and built a consultancy administration system using Ruby on Rails 1.2.3. Included employee, customer, schedule and contract management. The application also involved QuickBooks integration using web services.

    Software Engineer, Unboxed Consulting(2006 - 2010)

    Primary role as a contract analyst/developer. Was involved with financial administration, client relations, recruitment and marketing. Involved with strategic direction and business growth strategy.

    Software Engineer, Liquid Lime Studios (8 months 2006)

    Primarily built web based systems in PHP with a MySQL database. Converted sites from ASP to PHP. Built a shopping cart which could handle soft and hard goods as well as shipping costs. PHP web development, I was the lead developer on Adaa Entry for the Adobe Design Achievement Awards. Also was responsible for writing up functional specification documents, and client side requirements gathering.


    Certified Scrum Master

    University of Cape Town (January 2002 - November 2005)
    Bachelor of Business Science: Information Systems

    Information Systems, Business Strategy, Project Management, Operations Management, Microeconomics, Macroeconomics, Financial Mathematics, Statistics, Accounting, Finance, Business Law, Marketing.