Hi, I am Felix Geisendörfer, a programmer and entrepreneur living in Berlin, Germany.

I am a co-founder of Transloadit, a small, bootstrapped and profitable SaaS business, as well as Debuggable a web consulting firm.

A lot of my time is spent on open source, and I was one of the first users and core contributors of node.js.

One of my spare time passions is robotics, so a few friends and I organized an event around programming flying robots with JavaScript called NodeCopter which has now turned into a small community.

As of late, I have started to use Go for a lot of things. You should check it out, it's amazing.

You can find me on twitter and github, or contact me directly.


You can subscribe to updates via RSS or E-Mail.

Using TCP keepalive with Go Aug 26, 2014
GoDrone - A Parrot AR Drone 2.0 Firmware written in Go Dec 25, 2013
Vim Trick: Open current line on GitHub Aug 08, 2013
The Pull Request Hack Mar 11, 2013
Open Source And Responsibility Mar 07, 2013
Hello World Mar 03, 2013

I have been blogging since 2006, my older posts can be found here.


I enjoy speaking at conferences and user groups, so reach out if you'd like to invite me to an event.

That being said, I plan to do less traveling in 2013, so I can only attend a small amount of events this year.

tus.io - Squeezing Cats Through Tiny Mobile Tubes JSConf.us, Florida May 29, 2013
tus.io - Squeezing Cats Through Tiny Mobile Tubes Web Rebels, Oslo May 23, 2013
tus.io - Resumable file uploads for web and mobile apps Codemotion Berlin May 11, 2013
tus.io - Resumable File Uploads · pdf UIKonf Preparty, Berlin May 01, 2013
Programming flying robots with JavaScript · pdf NEXT Berlin Apr 24, 2013
Programming flying robots with JavaScript · pdf Railsberry, Krakow Apr 23, 2013
Programming an AR Drone Firmware in JS (de) · pdf Denkwerk, Cologne Dec 12, 2012
Programming an AR Drone Firmware in JS (de) · pdf · video Cologne JS Usergroup Dec 11, 2012
Faster than C? · pdf Prague JS Usergroup Nov 29, 2012
Flying robots over a 10.000 mile distance with JavaScript · pdf Sydney JS Usergroup Nov 21, 2012
Faster than C? · pdf Nodeconf.it, Italy Nov 11, 2012
The power of node.js (with quadcopters) · pdf · video Øredev, Malmö Nov 05, 2012
Faster than C? · pdf · video NodeDublin Oct 18, 2012
Faster than C? · pdf · video · code JSConf.EU, Berlin Oct 07, 2012
Programming flying robots with node.js · pdf · video LXJS Lisbon JavaScript, Lisbon Sep 28, 2012
The power of node.js (with quadcopters) · pdf Developer Conference, Hamburg Sep 07, 2012
The zen of node.js · pdf · video Campus Party Europe, Berlin Aug 22, 2012
Node.js Quadcopter Programming · pdf Berlin JS Usergroup Aug 16, 2012
As fast as C? · pdf · video London Node.js User Group Jun 27, 2012
Node.js - A practical introduction · pdf Big Techday, Munich Jun 15, 2012
The Node.js Scalability Myth · pdf Munich Node.js User Group Jun 14, 2012
Node.js in production · pdf · video Web Rebels, Oslo May 26, 2012
Bootstrapping Transloadit.com · pdf Roots, Bergen Apr 27, 2012
The Node.js Scalability Myth · pdf Roots, Bergen Apr 27, 2012
The Node.js Scalability Myth · pdf Mix IT, Lyon Apr 26, 2012
The Node.js Scalability Myth · pdf Berlin JS Usergroup Mar 15, 2012
JavaScript - The Bad Parts · pdf Berlin JS Usergroup Jan 19, 2012
Node.js - Best Practices · pdf · video Munich Node.js User Group Dec 01, 2011
Node.js - A practical introduction · pdf · video Munich Node.js User Group Dec 01, 2011
Node.js - A practical introduction · pdf · video Øredev, Malmö Nov 09, 2011
Building an alarm clock with node.js · pdf Reject.js, Berlin Oct 29, 2011
Node.js - Eine praktische Einführung Developer Conference, Hamburg May 21, 2011
How to Test Asynchronous Code Berlin JS Usergroup May 19, 2011
How to Test Asynchronous Code · pdf NodeConf, Portland May 05, 2011
Node.js - A quick tour · pdf Gameforge AG, Karlsruhe Apr 20, 2011
Transloadit · pdf Startup Riot, Atlanta Feb 16, 2011
Node.js - A quick tour Atlanta JavaScript Meetup Group Feb 15, 2011
Node.js - Should Ruby Developers Care? · pdf Atlanta Ruby Meetup Group Feb 09, 2011
Node.js in production · pdf Berlin JS Usergroup Jan 20, 2011
Node.js as a networking tool · pdf · video 27C3, Berlin Dec 28, 2010
Node.js - A quick tour Ruby User Group Berlin Oct 07, 2010
Dirty - How simple is your database? · video JSConf EU, Berlin Sep 25, 2010
Node.js - A quick tour Hamburg.js User Group Mar 04, 2010
Node.js - A quick tour Berlin JS Usergroup Jan 12, 2010
JavaScript and Git CakeFest, Berlin Jul 12, 2009
Recipies for successful CakePHP projects CakeFest, Berlin Jul 11, 2009
jQuery and CakePHP CakeFest, Buenos Aires Dec 05, 2008
Git and CakePHP CakeFest, Buenos Aires Dec 02, 2008
With jQuery & CakePHP to World Domination CakeFest, Orlando Feb 06, 2008
ActiveDOM jQuery Camp, Cambridge Oct 27, 2007


I help companies to make good technology decisions with a focus on node.js.

This often starts with evaluating if node.js is a good fit, and if so, training in-house developers to do the right things and coming up with good application architectures.

In other cases I've helped companies to review their existing code bases, as well as bringing failing projects back on track.

I also do small development projects, and can help you finding the right people to take on bigger projects.

Here are a few things my previous clients had to say:

Felix did a code review of our Node.js driver software. He came to us highly recommended, and now we understand the reasons for the high praise. He is extremely skilled, capable and balanced. He gave us excellent input about how to improve performance and coding standards. He worked quickly, efficiently and professionally. I strongly endorse Felix as an expert resource for Node.js projects.

Fred Holahan, VoltDB, Inc.

Felix took our legacy PHP API - and replatformed it in NodeJS - in 2 weeks flat. He worked with our internal teams to build capability and skills - in doing so and left us with a well formed, performant scalable piece of Node wizardary.

Nilan Peiris, Holiday Extras

As soon as you meet Felix, you know that you are talking to a special person, who is a true professional. Beyond his deep knowledge in the node.js platform, he has a rare talent for finding good and simple designs and architectures that will make your code more secure, elegant and maintainable.

We hired Felix in order to review our back-end code. Felix came with extremely high motivation and managed to go over most of the critical parts of the code in one day. The insights that he provided us were so valuable, that months later we are still fixing parts of the code and developing new features with Felix's comments and recommendations in mind.

If you are developing software, and you would like to make sure that you are doing it the right way, you should hire Felix

Itamar Weiss, UPcload

Felix is fantastic to work with - he is an expert in his domain and possesses an amazing ability understand and articulate problems and solutions, while also being one of those rare engineers whose productivity and quality are second to none.

I would happily work alongside Felix on any project, and would encourage anyone else to take the same opportunity.

Chris Leishman, ScreenSpeak

We are currently building a webservice with node.js which has very high performance demands. To check our codebase we recently booked Felix for a one-day code review session.

Without much introduction needed from our side we first listed the topics we wanted to discuss and were then immediately able walk through the critical paths of our code and discuss the relevant questions. Felix lead through the day in a very structured way and we had very fruitful discussions where the whole team could benefit a lot from Felix' incredible knowledge on software development in general and on node.js and webservices in particular. The day after the code review Felix provided us with a written wrap-up which contained all the conclusions drawn from our discussions during the review-session.

I can highly recommend Felix as consultant for every team that is seriously trying to build a webservice using node.js/javascript. It is definitely worth it!

Christoph Tavan, mbrtargeting

My availability for 2013 is limited, so email me if you need help with a project.


When not sitting in front of a computer, I enjoy a wide variety of sports. During the summer I mostly focus on playing beach volleyball, competing in tournaments pretty much every weekend. Other summer time passions of mine are street unicycling and slacklining. During the colder months I enjoy snowboarding, squash and badminton.

You might also be curious about the frog riding the squirrel used on this page. The picture is the result of being a huge squirrel fan (long story) and coming across the Get On The Squirrel Theres No Time To Explain meme one day. I really liked the carpe diem spirit of it, so I had an artist create a vector based on it. Eventually I want to use it as a logo on my laptop as well, but I have not gotten around to it yet.


My primary e-mail is felix@debuggable.com.

I love meeting new people, so if you're in Berlin, I'm almost always up for having lunch or something - just get in touch!

Please use Github for any questions or bug reports concerning my open source projects, this way the information can become useful to everybody.

I try to answer all e-mails, but sometimes I have a bit of a backlog.