CV - René Weteling

Freelance | Tech lead | Fractional CTO | Problem solver | Full-Stack development

About me

Tech has always been my passion, tracing back to my earliest memories of tinkering with gadgets and diving into computers. This enthusiasm drove me to pursue a bachelor's degree in IT sciences, which laid a strong foundation for my professional journey.

My career began at a design agency, where I collaborated with companies of various sizes, gaining diverse experience. Transitioning to freelance work allowed me to deliver optimal value to my clients, a role that invigorates and fulfills me.

I excel in building greenfield applications efficiently, from selecting the best development techniques to architecting the target infrastructure. By prioritizing automation, I ensure a seamless coding experience, leading to better project outcomes. Happy developers produce superior code quality.

I thrive on sharing my expertise with teams and organizations, enjoying their growth and success. Colleagues often describe me as a sociable hard worker with a keen sense of humor and a results-oriented mindset.

Skills & Knowledge

Here are the most pertinent highlights of my skill set:


Work, projects and experiences



Delivering healthy hot school lunches

12-04-2024 - Present

TommyTomato has a mission to turn all children into lifelong vegetable eaters. Plant a seed, harvest a healthy generation. They achieve this by bringing healthy, hot, and above all tasty lunches to schools. This involves a considerable amount of logistics; all lunches must be delivered hot and on time.

More about TommyTomato, click here

My role in this project:

  • Advise and support the on-site dev-team
  • Create CiCd setup in Github actions, feature and unit tests using selenium.
  • Adding new features
  • Fortifying the current monolith
  • Setup infrastructure using Terraform on AWS (fargate, rds)
  • Link the monolith to kafka, (producer/consumer)
  • Transfer responsibilities from the Rails stack to the Python stack

Felobo B.V.


01-01-2006 - Present

Back in school, I used to help my dad with IT solutions, and he suggested I start a business so he could pay me. So, I did! Since 2015, I've been freelancing full-time, and it's been a blast. Making the switch from a regular job to freelancing has been super rewarding. I get to learn from cool people every day and enjoy the flexibility it offers.

Asset management simplified

02-10-2023 - 11-04-2024 serves as a user-friendly asset management platform, simplifying the account opening process for clients. Leveraging a sophisticated questionnaire, Semmie accurately gauges associated risk profiles and proactively oversees investments. Clients enjoy comprehensive control via the convenient app or online portal. Moreover, Semmie extends the capability for advisors to manage these processes seamlessly through the advisor portal.

More about Semmie, click here

My role in this project:

  • Work on the OMS, API, Advisor portal (Rails application)
  • Adding new features
  • Troubleshooting complex bugs or and unintended side-effects

Odido / T-Mobile

TSC - Business router gui's

01-11-2021 - 28-09-2023

As tech lead for the Red team in the Operational Support Services department. Our primary focus is to create, manage, and support operational services to ensure the seamless functioning of our entire service portfolio. Creating and designing new greenfield applications to fit seamlessly in the current architecture. With over 18 applications to oversee, ranging from Node.js, Ruby on Rails to Elixir, this team plays a critical role in maintaining the uninterrupted operation of the company's core services.

More about T-Mobile, click here

My role in this project:

  • Design new reactive microservices that share core components to minimize overhead and duplicate code.
  • Work on multiple Rails, Elixir and NodeJs applications (19+ apps)
  • Updating internal commonly used plugins (gems and hex packages)
  • Setting up pipelines inside GitlabCi
  • General DevOps, provisioning Debian servers, load balancers etc
  • Troubleshooting issues


Media backbone for media outlets

01-11-2019 - 29-10-2021

MyChannels is a division within DPG Media group that is responsible for all digital content on all digital outlets of DPG.,,,, and so on. The team is compact, senior and knowledgeable. We are responsible for more than 5 million video plays each day. Creating services to supply the media outlets with videos, games and entertainment. Providing the mobile api for the Apps of the papers. And so on.

More about DPG, click here More about MyChannels, click here

My role in this project:

  • Work on the Video Management System (Rails application)
  • Work on the Video As A Service (Elixir application)
  • Setting up Services inside AWS (Terraform)
  • Trouble shooting issues


Parcel return software

01-02-2019 - 28-02-2019

Re:turnista is an app where clients of webshops can return items they bought. Using a mobile first app, the user is guided through a couple of questions and the package is ready for pickup.

The actual app is available here


Client portal for pensions

01-03-2019 - 31-03-2019

Vivat is the mother company of Zwitserleven, Vivat has an "My" environment where clients can log in and see information about their products. My team was responsible for the Pension funnel.

More about Zwitserleven here

My role in this project:

  • Changing the loading sequence for better performance
  • Moving from multiple separate loaders to one global loader
  • Small updates


Chemical e-trading system

01-04-2019 - 31-10-2019

Through DEPT I'm helping DigiB, that's the digital division of Brenntag, a worldwide chemical wholesale company to realize an ecommerce platform. The platform is built in React with Typescript, a NodeJs middleware that handles all api communication.

More about DigiB, click here

My role in this project:

  • Work in the front-end team to realize new features
  • Create React components
  • Connect the middleware to multiple API's
  • Help design a new event driven architecture (kafka)

Ace & Tate

Backend ecommerce system

28-05-2018 - 31-01-2019

Ace & Tate sells glasses online and offline, they have "currently" over 30 stores world wide and they use an e-commerce platform (Solidus) to process all orders. Since the company continues to change, the backend also needs to be quite versatile.

More info about Ace & Tate here

My role in this project:

  • Add features to the Solidus backend (Rails)
  • Deploy using Elastic Beanstalk (AWS)
  • Maintain and update the over 30 private gems
  • Add detailed tests for existing and new features


Admin interface including API for gasoline loyalty program

22-01-2018 - 27-04-2018

Tankey is a loyalty platform (LP) created by Essent for their other brand EnergieDirect. The first version of the LP is built within Essent. Meaning that linking other company's proved to be difficult, that's why they have split up Tankey from essent and built a new and better version of the app.

More info about Tankey here

My role in this project:

  • Build a Rails Api to supply the android and ios clients with data
  • Build an Admin interface where you can see KPI's, export transactions and get insight in what's happening
  • Build a stable and traceable system, with the new GDPR rules we need to track when consent is given etc.
  • Link the backend to a push notification provider (firebase) so that we can notify our users
  • Talk with the teams to find out what they are building next so that i can supply the data on forehand
  • Create a discount calculator, and method to stack discounts
  • Link the api to the loyalty partners (Energie direct, and more to come), since you only get a discount when you are linked to a specific loyalty partner.

Abn Amro

Cybersecurity awareness app

04-12-2017 - 25-01-2018

Veiligzondermoeite started out as an experiment from ABN Amro to help their cybersecurity office create awareness with clients of ABN Amro. There are alot of cybersecurity threats that are just not preventable with a technical solution like a firewall or password resets. Human engineering is currently quite hot. Just imagine, some hacker hacked the CEO’s email account, then the CEO goes on a well deserved vacation, and then the hacks send an email to the chief of finance to pay 10K to some IBAN account. This is a case that you can prevent with awareness and that’s why The main ingredient was tasked by ABN Amro to create this app.

My role in this project:

  • Build a Node.js backend to supply the app with content and send Push notifications when new content is added
  • Build a React Native app to create awareness about cybersecurity


React - Webpack - Jekyll

16-10-2017 - 17-11-2017

With the BotSquad bot, you can create bots for the web, mobile and chat interfaces like facebook, slack, twitter etc. There is a beautiful studio where you can create bots using a friendly and semantic DSL. And preview the bot in real time.

My role in this project: 

  • React coding on the Chat client
  • Creating the API
  • RnD on the bot itself
  • Adding features

HalloRoos - SNS experiment

Rails - Roos API - Heroku

11-10-2017 - 08-11-2017

HalloRoos is a contract alarm platform where users can set alarms for contracts that will expire in the future so that they can switch providers on time. HalloRoos was looking to extend their functionality and needed a developer to help them reach their goals. The subject itself is somewhat sensitive, but it comes down to a pretty selection then order flow with alot of validations and constraints. Each step is communicated to an API provided to store and manage the data.

My role in this project:

  • Build the pages as described in Rails using Slim, Sass, and CoffeeScript
  • Connect the pages to virtual models so that we can apply validations
  • Persist the validated models to the provided API

Van Ons B.V. - Carpet App

React - LibVips - OpenVc - DeepZoom

02-06-2017 - 13-09-2017

Van Ons is a really cool WP design agency based in Amsterdam. For some projects, they contract out for special features and this was quite special. They wanted to create a web interface were clients can cut out a portion of a really big image (30 by 30 meters at 76 dpi approx 46GB per image). So I've developed a React frontend where the users can walk through the image using DeepZoom. And cut out a shape and then sending the coordinates to a worker server, cutting out the piece and mailing it to a carpet printer. Pretty heavy stuff.

Everything was new, everything was exciting, it was an awesome project. The final version is visible here at Skonne

My role in this project:

  • Build a react app to define the area that needs to be sliced
  • Create a slice worker server that slices the image according to the dimensions provided by the react app
  • Figuring out how to slice images as big as 46GB each

Revolve Music

CTO - Rails - AWS - CI - rSpec

03-04-2016 - 15-09-2017

Revolve Music is a SAAS platform where users (Artists mostly) can create a website, a digital presence in just a few minutes. Connecting to filled content providers like SoundCloud, BandsInTown, LinkedIn, Twitter etc your site is filled with content and you are ready to go.

My role in this project:

  • Clean up and rebuild existing code (the overall quality was very poor and not very robust)
  • Create a Continuous integration environment using CircleCi and AWS container service
  • Creating a global scaling web server setup using: Route53, AWS EC2, AWS EC2 container service, Cloudfront, RDS, S3 and Docker
  • Being responsible for the Technical day2day, building team culture, applying standards, laying out technical roadmaps etc. CTO stuff.


Onboarding software for large companies

01-05-2015 - 01-02-2016

Leaplines is a SaaS that helps companies with their on-boarding process. Providing a curriculum based on the employee's role within the company, with a clear hierarchical method of stimulating the users through there managers.

We made use of the following: Rails, PostgresSQL, CircleCI, Github, Rspec with Capybara ( TDD ), jQuery, React, Rails UJS

My role in this project:

  • Going to clients, getting feedback from the source
  • Building new features, mainly onboarding exercises in for form of a game
  • Scrum plannings etc

Horyon innovaties B.V.

Android process app, Rails backend

15-10-2015 - 01-09-2022

Horyon innovaties B.V. is an asbestos removal company. Asbestos has a bad reputation and that's why there is a lot of legislation. They are required to have all data on premise at all times. This is just not possible on paper, so we have created a Rails backend with a Restful api connecting an Cordova Android app. The app started out as a simple hour measuring platform, but now it has over 18 main functions and one of them is drawing on a photographed map.

My role in this project:

  • Design the product matching the needs of the business
  • Creating a Rails backend, with role based authorisation
  • Ops: it runs on my own High availability cluster powered by
  • Creating the React Cordova android app - employed

iOS, cordova and react development

01-07-2012 - 01-04-2015

Coming back to click felt really good. They had so much faith in me that they wanted to set up a new office in Amsterdam with the main focus on Mobile. We had some really great clients. We have build an app for KPN where users can view the last goals in a soccer league. Build an app for a recruitment agency and many more. - employed

Symphony - Php - Less

01-08-2011 - 01-07-2012

This is the first time i got in contact with a proper framework. Symphony. It's mature, it has a rich plugin ecosystem, its consistent. I liked it allot. Learned a lot here, the main issue was that i was the only dev in the company so i got a bit bored and moved on. Great experience though. - internship then employed

Perl - CaretCMS - Scripting - Discovering

01-12-2008 - 01-08-2011

My internship at was great, a young team, cool founders, nice environment and Dirk the dog. I've learned so much here, multiple languages, dynamics in the company's themselves. Learned about budgets, stakeholders, planning etc. It was a great experience.