E-Mail: nick@groenen.me
Website: https://nick.groenen.me/
LinkedIn: https://www.linkedin.com/in/nickgroenen/
GitHub: https://github.com/zoni/

I’m a Site Reliability Engineer at Castor, an international healthcare company working to accelerate medical research by building a modern data capture platform for clinical trials.

My core strengths lie at the intersection of operations, software development and information security.


While not an exhaustive list, the following topics form the core essence of what I am experienced with and most enjoy working on:

  • Site reliability engineering
    • Technical aspects such as automation and configuration management, CI/CD pipelines, establishing service metrics and improving observability
    • Cultural aspects like technical writing and documentation, setting up sustainable on-call rotations, facilitating post-incident reviews (“postmortems”) and mentoring developers on operational concerns
  • Software development
    • Primarily interested in pursuing opportunities involving Elixir or Rust
    • I’ve also written Python and Go (golang) professionally
    • Recruiters: Yes I also know how to write shell scripts (like bash)
  • Highly available, distributed systems, large-scale infrastructure & deployment orchestration
  • Information security, both from a technical perspective as well as a management perspective including risk assessments, policy design, awareness trainings, etc.


Engineering Team Lead - Platform at Castor

April 2021 - Present. Amsterdam, Netherlands

I’m still a Site Reliability Engineer, however the title change to Engineering Team Lead reflects that I am the lead of the platform team, which manages the (infrastructure) platforms that Castor’s applications run on.

Chief Information Security Officer at Castor

October 2019 - Present. Amsterdam, Netherlands

Though I joined Castor primarily as an SRE, I also took on CISO responsibilities when a dedicated hire for this didn’t make sense. With Castor growing rapidly, I am looking to dedicate myself fully to technical work again, which I blog about in “stepping down as CISO".

  • Helped scale security and compliance processes while growing from about 40 to 100 employees across offices in the EU and US.
  • Played a key role in leading Castor through a recertification audit of ISO 9001, ISO 27001 and NEN 7510.
  • Implemented a Single Sign-On solution for internal services together with the IT department to reduce account management burdens and more easily meet compliance requirements.
  • Implemented endpoint security monitoring together with the IT department to improve adherence to security policies, while remaining conscious and respectful of employees’ privacy.
  • Facilitated response to security incidents, including investigation, remediation and communications (internal and external).
  • Ensured Castor would meet the security requirements of the World Health Organization (WHO) to support their SOLIDARITY trial on COVID-19 treatments.

Site Reliability Engineer at Castor

February 2019 - March 2021. Amsterdam, Netherlands

I joined Castor as the first and sole SRE and helped shape their infrastructure/platform roadmap throughout their Series A investment. Notable projects and accomplishments during this period include:

  • Led the transition from doing ops management by hand to using Infrastructure as Code principles with Ansible and Terraform.
  • Helped shape strategic efforts to migrate away from local managed hosting providers, standardizing on Microsoft Azure‘s cloud services. 1
  • Launched a dedicated server offering (“Castor Private Cloud”) on Azure.
  • Designed and built automation to perform a cross-region migration/split of Castor’s entire user database with minimal downtime and strong operational guarantees to avoid manual error.
  • Opened up a new EDC region in Australia (also on Azure).
  • Played a key role in leading Castor through a recertification audit of ISO 9001, ISO 27001 and NEN 7510.

Developer & security officer at StartMail

February 2017 – January 2019. The Hague, Netherlands

I was one of the senior developers at StartMail, a privacy-focused email service. During my two years there my team worked on rebuilding all of StartMail’s core infrastructure, including a tricky customer migration which was completed without incident.

After completion of the project I continued to work on further infrastructure improvements and assisted in the rewrite of their frontend webmail application from an 90’s-style PHP webapp (helloooo SquirrelMail!) to modern javascript with a Python backend.

In addition to my role as developer I also served as StartMail’s security officer, responsible for implementing security policies and having knowledge of fun acronyms such as ISO/IEC 27001, HIPAA and GDPR.

DevOps engineer at Byte

November 2014 – January 2017. Amsterdam, Netherlands

I worked in the role of DevOps engineer (buzzword alert!) at Byte, a webhosting company specializing in PHP and Magento E-commerce hosting. I did systems administration with a heavy focus on automation, writing and maintaining software systems which supported all aspects of Byte’s infrastructure.

  • I was the team lead for the “platform quality monitoring” specialization within Byte, which meant I was responsible for all aspects of monitoring/alerting/metrics collection (a lot of this involved Nagios/Icinga, Graphite, ElasticSearch/Logstash/Kibana).

  • I was the team lead for the “provisioning” specialization, which meant I was responsible for all higher-level/company-wide provisioning/automation efforts. A large part of this involved managing the Puppet and Ansible infrastructure, automation scripts and a number of supporting API services (mostly in Python/Django).

  • I was a member of the mail specialization, responsible for all email services offered to Byte’s customers. This involved maintenance of dovecot and postfix mail clusters, the implementation and upkeep of spam-filtering software and implementation of custom rate-limiting and accounting software.

  • I was a member of the security specialization, which concerned itself with all aspects of security, from tracking security advisories and rolling out security patches to raising general awareness about various aspects of security.

While at Byte, I also helped implement ISO/IEC 27001:2013.

Further past

Developer at TravelBird

August 2013 – November 2014. Amsterdam, Netherlands

Web developer at a&m impact internetdiensten

October 2011 - July 2013. Doetinchem, Netherlands

System administrator/Application developer intern at the National Center for Supercomputing Applications

July 2009 - August 2009. Urbana-Champaign, Illinois Area, USA


Bedrijfshulpverlener (emergency response officer) at Castor

May 2019 - Present. Amsterdam, Netherlands

The Dutch Working Conditions Act states companies need to ensure adequate emergency response measures, known as bedrijfshulpverlening. In most companies this translates to having one or more employees trained as emergency response officers. For Castor, I operate as the head of our emergency response organisation.

Evenementenhulpverlener at the Red Cross Haarlemmermeer

August 2019 - Present. Hoofddorp, Netherlands

As a volunteer for the Dutch Red Cross, I help provide first aid at various small- and large scale events throughout the Netherlands and help out with the current, ongoing COVID-19 pandemic.


B.B.A., Business Administration at a&m impact internetdiensten

2012-2013, Doetinchem, Netherlands.

This was a joint employer- and government-sponsored two-year education program that would have seen students gain a B.A. degree in Business Administration by combining study with daily work. Unfortunately my employer at that time (a&m impact internetdiensten) chose not to continue the program after the first year. As such, I was unable to finish and did not obtain a degree.

Bc., Computer Science at Radboud University

2007-2010, Nijmegen, Netherlands

I studied computer science at the Radboud University in Nijmegen, however I finished only about 2 years of courses before stopping my studies. As such I did not obtain a degree.

VWO profiel Natuur en Techniek at Arentheem College

2001-2007, Arnhem, Netherlands


Certified Incident Responder

PagerDuty University, Certificate number z2po3xomjd33

Level 1 Certificate in English (ESOL)

University of Cambridge, License 0012247650

European First Aid Certificate (EFAC)

Red Cross certificate number nrks10028399-71892.
Includes various additional certifications, including:

  • Aantekening Eerste Hulp aan baby’s en kinderen
  • Aantekening Eerste Hulp bij acute sportletsels
  • Aantekening Eerste Hulp bij wandelletsel
  • Evenementen Eerstehulpverlener
  • Mentale Eerste Hulp
  • Verbindingsdienst - Omgaan met portofoon en mobilofoon
  • Stop de bloeding

Beheerder brandmeld- en ontruimingsalarminstallatie

NIBHV, Candidate number 890127050


I believe too little attention is currently given to ethics in the field of IT and related industry so I’d like to explicitly call out that I hold myself to both the ACM Code of Ethics and Professional Conduct as well as the IEEE Code of Ethics.


The latest version of this document is available on-line in a variety of formats:

  1. Azure would not have been my first pick on a purely technical level, but within the medical sector Castor operates in there were other, non-technical concerns that made it a better pick than AWS and GCP. ↩︎