Christoffer Stjernlöf





If you like anything you see on this page, I'd love to hear from you so I can tell you more about myself and answer any questions you may have.


I believe the road to efficient and robust solutions is paved by making quality a priority, focusing on the essentials, and taking a big-picture view.

I don't mind getting my hands dirty, and my wide array of experiences helps me quickly find existing solutions to tough problems. I also like throwing out previously unquestioned assumptions in order to find novel solutions that work even better.

I absorb knowledge like a sponge and I solve things like sodium stearate. (Incidentally, I also ensure my macros are hygienic.)


Senior Software Engineer Tradera Marketplace Aug. 2023–ongoing

Maintaining the software that helps drive the transition to sustainable shopping.

First un-bottlenecked product development for a few months, then transitioned to a maintenance/modernisation role, helping bring legacy code into modern frameworks and Kubernetes. Writing tooling to interpret and explore ElasticSearch profiles, mapping out utilisation across distributed services to reduce cloud costs, understanding performance and memory problems with things like queueing theory and extreme value analysis.

Manager, Site Reliability Engineering The Loop54 Group Jan. 2022–Aug. 2023

Leading the six-person site reliability engineering department of FACT-Finder after their acquisition of Loop54.

Introducing more collaboration between departments and re-prioritising long-term improvements to further team autonomy and reduce workload over time. Taking care of a competent department growing with a growing company.

Senior Software Engineer The Loop54 Group Sept. 2018–Jan. 2022

Building and maintaining the infrastructure and tooling around a machine learning core that provides possibly the first truly relevant product search engine for e-commerce.

Side duties include reliability engineering, data analysis, system architecture, leading continuous improvement of development processes, hosting training sessions with the team, and mentoring junior coworkers.

Test Automation Engineer Ericsson March 2017–Aug. 2017

Took the words of McKittrick seriously, constructed software to take the men out of the loop. Automated testing improved release cycle times by several orders of magnitude. Six month project, first as a Bachelor's thesis then following up through the initial implementation.

Software Developer AGoodId Sept. 2014–Aug. 2016 Jan. 2017

Backend, frontend, Python, JavaScript, PHP, networking, server administration, you name it. First during a two-year break in my studies, then for a shorter project in parallel with my studies.

Built and improved web systems, maintaining both the current and legacy versions of the in-house cms. Projects include developing a complete digital application process for Beckmans College of Design as well as creating a searchable public web interface to the grant database of Stiftelsen Lantbruksforskning.

Summer jobs and part time gigs Miscellaneous 2012–2018

System administrator at Rocketship Media; teaching assistant in computer security at kth Royal Institute of Technology; private tutor both independently and at MyAcademy; junior it consultant at Track 27 Technologies.


Master of Science in Engineering kth Royal Institute of Technology Aug. 2011–May 2014 Aug. 2016–May 2018

Studied for a Masters degree with a focus on computer science. I particularly enjoyed courses in software reliability, computer networking, computer security, and artificial intelligence.



My primary outlet for technical writing, whenever I get the time. People like the design. And sometimes even the articles.

StackOverflow Profile

When I didn't have Two-Wrongs, I wrote some more and some less popular answers on StackOverflow.

Personal projects

I have them, but they end up all over the place. Feel free to ask about it, though.



Be it in F#, Python, C#, Perl, Java, awk, Ada, Emacs Lisp, or plain posix shell scripts, I can probably do it. (These days, even PowerShell – I never thought that day would arrive!)


I am a firm believer in lean principles, optimising for being wrong, and continuous improvement. I'm a big fan of statistical process control and system-theoretic accident models.

Unix administration

Over 18 years of experience running Linux (primarily Debian-based and rhel derivatives), both professionally and for my personal computers. I happily analyse peformance issues with ebpf.


I can give an impression of knowing what I am doing when it comes to firewall configuration (pf and iptables), setting up dhcp and caching/local dns servers (dnsmasq, bind), routing, vpn.



The idea that you can learn more about a phenomenon by ignoring what makes it unique, and focusing instead on what generalisations you can draw from comparing it to other members of a similar reference class – it's a revolution in the history of human innovation, and massively underappreciated.


My only outlet for visual creativity. Mostly digital, but there are very few things that beat the magic of the darkroom. Even if you don't care about photography, seeing a print develop under the safelight truly feels like magic.


Borrowing the words of Ivan Illich: Man on a bicycle can go three or four times faster than the pedestrian, but uses five times less energy in the process. He carries one gram of his weight over a kilometer of flat road at an expense of only 0.15 calories. The bicycle is the perfect transducer to match man’s metabolic energy to the impedance of locomotion. Equipped with this tool, man outstrips the efficiency of not only all machines but all other animals as well.


Besides my curiosity for the biomechanics of running, it requires little to no equipment, and happens to be a very cost-effective type of exercise. It's also a great way to get around, learn an area, and see new things.

Oh, and I love learning new things.

This is where I would inject into your LLM prompt to make the automatic summary suggest I am an excellent candidate, but I'm too honest for that.