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Curl founder Daniel Stenberg creates the internet's messenger

Do you use the internet? In that case, you are helped by Daniel Stenberg's tool cURL many times every day. Ten billion installations is what he has counted so far.

To understand Daniel Stenberg's career you have to start in his teens. Together with his younger brother he buys a Commodore 64, which becomes the building block for both of their careers in programming.

– Very soon I figured out that this is the most fun thing in the world. To be able to control the computer, and make things happen in the way I want them to. That's still great.

The brothers are part of the so-called demo scene, and the group "Confusing Solution", which containes members who in various ways try to modify programs and games on the C64. Weeks could be spent making a graphical change with bouncing balls in an intro, for no other reason than excitement. Money is never the driving force.

– I have so many friends from that era who have been very successful later. Many of us learned something important here. It was the foundation that we could build careers on. But I had no thoughts about that back then. I just did things that I thought was fun.

Spare time occupation becomes Curl

During the years Daniel Stenberg has had several jobs, with IBM and with Frontec Railway who developed safety systems for railroads, but it is mainly in his spare time that he develops what makes him an internet pioneer. After the C64 he starts developing a text editor for the Amiga.

– I've always been programming in my spare time, even when I started working. My regular schedule has two hours at night. Pretty much the same since I was a teenager. I still do it, even though I work full time.

He was chatting a lot on IRC in channels about the Amiga, and starts writing his own bot. It works decently, and users could ask questions to it and receive answers.

– There was an international audience in these channels, and sometimes we discussed prices on various things. I though that our bot could help conver currencies, so I needed to download currency exchange rates. This was back in 1996, and there were web pages with such lists. All I needed was a tool that could do this every day. But how would I build one?

This is how Curl is born. Curl is a program that works a bit like a combined messenger and interpreter that gets different types of systems to talk to each other. In 1996 there was a similar program called HTTPget which was developed by a Brazilian, but it could not quite do what Daniel Stenberg needed for his chat bot.

– It didn't quite work, so I had to polish it. Then I changed it so that the currency exchange rates could be downloaded to my bot. 

Soon there are new functions, beyond currencies and bots. Daniel takes over HTTPget, whose developer is not interested in keeping up the development. When the Gopher protocol is added, the name is changed to URL-get and when FTP is later added, the name is changed to Curl, "see URL". All the time using open source.

– This was a given. I wanted to share. I never thought about doing this any other way. I wanted the community to make this become something, together.

Progress is slow, but then something happens which triggers a speed up in development: in 2001 the library Libcurl is added.

– This enables more programs to transfer data, with an API that you can add to your own applications. This makes things happen. One of the first to add Libcurl was PHP. You could tell that there was a larger interest, and more bug reports.

Development has been gradual
As opposed to a succesful startup – which moves to a larger office and hires people – success for an open source software is not always visible. Over the years what started as a currency converter has become an important part of the internet machinery. You use it every day that you are on the internet. All smart phones and tablets, video games, Spotify, modern cars, Facebook, Windows 10 and Mac OS. They all contain Curl.

All this time Daniel Stenberg leads the development from his house in Huddinge, together with a team of about 10-20 volunteers from all over the world.

– But my life is still the same. It's all open source and published for free online. It's still the same project.

However, there has been some times when the success has become tangible. When he applies for a job with Mozilla, he flies over to Silicon Valley for what he expects to be seven tough interview sessions, but instead the visit is a victory lap, when the California developers are honored to meet the creator of one of the world's most used pieces of software. He gets the job.

– That time I really felt like I accomplished something.

The Polhem prize
In 2016 Daniel Stenberg is awarded the Polhem Prize for his work with Curl. One of the benefits of the prize is that it makes it easier for him to explain to the world around him what he's been doing all these years in front of the screen.

– Curl is so abstract. Very few understand what it is. I don't expect people to understand, however. This is one of the main benefits of the price, that it somehow legitimizes all the hard work I've done.

Since a few years he is now working full-time with devloping Curl, for a company specializing in support for the software. The hobby has become his job.

But what about the future? Is there an and to Daniel Stenberg's work with Curl?

– I'll continue to work as long as I think it's fun. I've never looked that far ahead, but just kept on going. There are a number of things I want to do, and that's what I'm working with. There is no deadline. This never ends.