Vincent van Leeuwen

May the force be with you.

Read this first

Bitcoin and the hype cycle

A few months ago there was an interesting blog post about how the bitcoin price chart shows quite some similarity with the hype cycle. Stating from Wikipedia (for those who have never heard of the hype cycle):

The Hype Cycle is a branded graphical presentation developed and used by US Information Technology (IT) research and advisory firm Gartner for representing the maturity, adoption and social application of specific technologies. The Hype Cycle provides a graphical and conceptual presentation of the maturity emerging technologies through five phases.

It looks like this:

At the time of writing, roughly six months ago, it was already interesting to look at the bitcoin price chart from this perspective. But flash forward a few months, and notice how the similarities seem even more apparent:

Screenshot 2015-12-05 20.12.30.png

Continue reading →

My reason for writing

I recently read the excellent book by Dale Carnegie on How to Win Friends and Influence People. I initially thought the title sounded a bit shady, but its one of those books where you’re misled. The book is much more about how to become a genuinely nicer person, rather than faking it.

But one of the key things I took away from How to Win Friend and Influence People, besides the actual scope of the book, is how quickly we forget. Carnegie recommends to read his book twice, rather than just once, and to keep taking notes continuously. That is, if you plan to remember at least half of it. And he is absolutely right. Already a few days after reading the book just once, I surely remembered less than half of what was inside. Unbelievable how much we can forget in just a few days!

I believe there is a larger trend going on here. We process so much information these days, that we simply forget...

Continue reading →

Steward, Oz and Tazzy

This is my third update while backpacking in kiwi-land. The previous ones you can read here and here. I’m not really into writing a diary or travel log, so I figured I’d just share some pictures that I’ve taken on my trip with some comments.


Early March I arrived in on Steward Island to hike the Rakiura great walk, among things. I usually love islands, and this one was no different. It was a beautiful place, as you can see from this picture of sunset over Halfmoon Bay in Oban.


Steward Island is home to about 20000 Kiwis (versus about 800 human inhabitants). Unfortunately though, this sign was the closest I came to seeing one after spending close to 3(!) hours sitting on the edge of a damn rugby field. Stupid birds.


Via a short stop in Auckland, Wouter and I flew up to Brisbane to meet up with Dwight in his natural habitat, the Gold Coast. This is a picture of Mr. D. driving us...

Continue reading →

Upload an image with Swift & Django REST API framework

This post is about how to simply upload an image via a POST request in Swift. I’m relatively new to Swift and programming for iOS, and there doesn’t seem to be too much documentation about these things around, so I figured I’d share how I did it here, so others may benefit.

Basically wat I was looking to do was POST an UIImage in Swift to a Python / Django written API set up with the Django REST Framework. I use the CreateAPIView, which accepts multipart form data.

1) Django POST API

The image is stored as an ImageField, together with some other customer data params, let’s for simplicity say just name and email. To give you an idea of my Django setup:

def get_image_path(instance, filename):
    Puts image in MEDIA_ROOT/photos/instance_id/file
    return 'orders/%s/%s' % (, filename)

class PhotoOrder(models.Model):
    photo =

Continue reading →

Update from the far end of the world

This is my second update while backpacking in kiwi-land. The first one you can read here. I’m not really into writing a diary or travel log, so I figured I’d just share some pictures that I’ve taken on my trip with some comments.


On the 31st of January, I started to hike my first Great Walk, named after the Dutch explorer who discovered New Zealand back in the days. Its funny how this mister Abel Tasman is quite famous in New Zealand, while back home hardly anybody seems to know who he is.


The Heaphy Track was the second great walk I hiked, and also the longest, walking 82k in 3 days. Especially the second day was incredible, starting out in the mountains and ending at the Tasman sea. While the trail descended, the surrounding forest ever changed. Where in the morning I had only seen small alpine plants, at the end of the day I was surrounded by large fern trees and palm trees. It...

Continue reading →

Travels part I - Hong Kong & New Zealand (North Island)

Quite some friends and family asked me to share some updates while backpacking in kiwi-land. I’m not really into writing a diary or travel log, so I figured I’d just share some pictures that I’ve taken on my trip with some comments. Since there might be some international friends reading this, I wrote everything in English to keep it simple.


I had an eleven hour stopover in Hong Kong on my flight to NZ. One of the cool things to do is visit Victoria Peak, which overlooks Hong Kong island. From here you can see the impressive Hong Kong skyline, even when the weather isn’t that great.


Kowloon Markets, which is on the main land just next to Hong Kong island.


A bit of a gruesome picture, I know, but it does sum up Hong Kong’s street life quite well. This guy was actually lying in front of Hong Kong’s most luxurious shopping mall, totally passed out. Income inequality in Hong Kong is...

Continue reading →

The killer app for learning JS

I’ve recently been learning JavaScript through EloquentJavascript (EJ) tutorials. Somebody on reddit pointed me to it, and I must say: Its been absolutely insane. This is by far the best tutorial I’ve seen in a long, long time. And being a self-taught programmer, I’ve seen quite a few. I would definitely recommend it to anyone, whether you’re just getting started or a bit further ahead. EJ starts really easy, explaining how basic concepts like arrays and variables are set up in JavaScript. But already in chapter 6 & 7 your head starts exploding with higher order functions and object oriented programming.

I find EJ even more very interesting because the momentum Javascript currently has when it comes to Web development. As much as I love Python, JavaScript is probably a much better place to start right now if you’re looking into Web Development. Especially because it can be used client...

Continue reading →

The dark side of being technical

In the past, I’ve written a fair bit about why non-technical founders should consider to pick up coding. Although I still believe that there’s a lot of truth in this, I’ve recently also experienced a downside of becoming more technical as a founder.

In recent months, me and my co-founders have been brainstorming some new startup ideas. Which, as a side note, can be quite a dangerous activity in itself already. Now that I’ve become a fair bit more technical over the years, I can’t fail but notice how it has become even more dangerous. A few years ago, when I found a problem I was passionate about, I would be happy with a vague understanding what my solution would do. I wouldn’t worry for a second how it should actually work. Nowadays its a bit different. The first thing I often can’t help myself thinking is: Could I build this? How would I solve this efficiently? This is a whole...

Continue reading →

Facebook is fucked

I love it when my non-tech, non-startup friends are going mental over a new product or service. To me, this is one of the best early indicators that a startup has gone mainstream. A few years ago, this happened for the first time when everyone around me started inviting me to become Farmville neighbours. With Tinder it happened again. All of a sudden, several of my friends were bragging how they were on a dating streak thanks to a new mobile dating app. As I’m aware of most of their personal track records, this instantly caught my attention. It appeared to be Tinder. Yet again, a startup had gone mainstream.

After last week’s What’s App acquisition by Facebook, my mainstream alarm bells rang once more. A few days later, I was asked whether I had already installed Telegram on my phone. I had no idea what my friends were talking about. I never heard of Telegram before. But obviously...

Continue reading →

Stop bitching. Start creating.

I recently overheard a discussion that got me thinking. Two people were in the middle of a debate about “true entrepreneurship”. Can it be taught? Or is it something you’re born with?

I do not believe entrepreneurship is something you’re born with. To me, “true entrepreneurship” is in essence about the difference between a constructive state of mind and a critical state of mind. The difference between those who keep complaining about missed chances, and those who are celebrating upcoming opportunities. The very difference between people who feel sorry for themselves and those who push harder.

It surprises me how often people confuse a critical mind with a visionary mind. There are too many societies, including here in the Netherlands, where being critical on just about anything is highly overrated. I love how this comes to light on a micro scale during the typical crowd response at...

Continue reading →