– Everything I know and learned about running and maintaining Open Source projects for three decades.
For several years now, I have had a blog post series in mind to describe something about what people could expect to happen in Open Source projects. I had a few already half-started blog post drafts for some sub topics.
I couldn’t really make up my mind how to craft a series of blog posts about this wide topic in a sensible way so I kept postponing it for later. I did this for years.
A book, it has to be a book
It just dawned on my one day: the only way to get all this into a comprehensible way that also can hold all the thoughts I would like it to have, is to put it into a book. By book, I mean a document. An essay. A collection of pages. A booklet maybe. I don’t know how many words it might end up to become and I have no illusions of it ever ending up in print.
I mean to write the document in the open and provide it for free, online. Open Source style.
Day one
I grabbed my original draft for my blog series “You can expect this in your Open Source project”. I had worked on that document in the background for a long time, adding some little thing here and there over years – and it now had maybe twenty-five “lessons” listed with a short paragraph of text next to each.
I also had started three blog posts based on such lessons that were in pending state here on daniel.haxx.se in my queue of drafts.
I first copied the blog post content back into the text file from those potential blog posts, before I deleted them, and converted the entire file to markdown.
I then grouped the “lessons” I had listed in the markdown file and moved them into a few different sections. Like what to expect, code, money, people and project. I put subtitles into separate files for those five main areas.
How hard can it be?
I didn’t want to do a lot of work before I put the thing into git, and I didn’t want to run any private git repository so I had to make a new repo with a name. I went with “How hard can it be” as a working title and created the repo on GitHub. On April 6 I made the first git push with initial contents to that repository.
The first external contributor appeared after just a few minutes with the first pull-request fixing typos. Clearly people are following me on GitHub and spotted the creating of the repository and checked out what it was. I hadn’t told anyone or given any pointers.
I started expanding on subjects in the book.
Let’s get a real title
In the evening of April 7 I posted this question on Twitter:
I got a flood of replies. Lots of good ones and also lots of fun and sarcastic ones. The one that I think really talked to me the best was also the shortest: Uncurled.
It’s short and sweet
It includes a reference to curl without saying it is “a curl book” (it isn’t)
The topic is a bit about “untangling” and curl is a project that probably has taught me the most of what I include here
It sounds a little like “debriefed” from the curl project, and it is…
I can put it up on the domain name un.curl.dev
I figured I could possibly go with a longer subtitle that could explain the book more: “Everything I know and learned about running and maintaining Open Source projects”.
A name
I renamed the GitHub repository and added a description there. I created the URL (by adding the “un” CNAME entry in the “curl.dev” domain) and I setup gitbook.com to render the content to appear on un.curl.dev.
With a little more thoughts and then spilling some beans about my plans in my weekly report on April 8 (but not leaking the URL or repo to anyone yet) that made people provide some more ideas, I added more content.
10,000 words
By the evening of April 9, I surpassed 10,000 words of contents. Still having the contents and the order of everything pretty much in flux and not yet sorted out.
20,000 words
On April 25, I surpassed 20,000 words. It starts to look like something I can announce soon.
Getting there, but not done
The uncurled book is now in a state I think I can show off without feeling embarrassed. I believe I will still need to work on it more going forward to add and polish content and make it more coherent and less of a collection of snippets. I hope that I over time can settle down and gradually slow down the change pace. It will of course also depend a lot on the feedback I get.
Cover
Since it doesn’t exist physically and probably never will, I don’t think it actually needs a cover image, but it would probably be cool to still have one to use as an image and symbol for the book. If someone has a good idea or feels artistically inclined to make one, let me know!
I didn’t expect this, and this year I wasn’t asked ahead of time if I wanted to receive this gift. It is however something of a collector’s item that I find very enjoyable.
I received my GitHub contribution matrix printed in steel. This is my 2021 contribution skyline. (Click the images for higher resolution.)
The thing is surprisingly heavy and sturdy. If I had papers lying around, this would an awesome paper press.
You might remember that I got a similar gift last year, so it felt natural to do a comparison shot of 2021 and 2020.
For 2020, GitHub counted 2,466 contributions, while I reached 2,543 in 2021. Very similar numbers, but clearly distributed very differently. The two matrix images look like this.
2020
2021
Letter
Enclosed with this gift was also a friendly and encouraging letter.
It was a while since I last spoke Swedish on a podcast. I joined the friendly hosts Sebastian and Alex of the Trevlig Mjukvara (translates to something like “Nice Software”) podcast and we talked software development, open source, curl, Mozilla and a few other topics for an hour. I had a great time. (We had Jitsi act up on us more than once so we had to switch away from it mid-recording!)
On Friday January 21, 2022 I received this email. I tweeted about it and it took off like crazy.
The email comes from a fortune-500 multi-billion dollar company that apparently might be using a product that contains my code, or maybe they have customers who do. Who knows?
My guess is that they do this for some compliance reasons and they “forgot” that their open source components are not automatically provided by “partners” they can just demand this information from.
I answered the email very briefly and said I will be happy to answer with details as soon as we have a support contract signed.
I think maybe this serves as a good example of the open source pyramid and users in the upper layers not at all thinking of how the lower layers are maintained. Building a house without a care about the ground the house stands on.
In my tweet and here in my blog post I redact the name of the company. I most probably have the right to tell you who they are, but I still prefer to not. (Especially if I manage to land a profitable business contract with them.) I suspect we can find this level of entitlement in many companies.
The level of ignorance and incompetence shown in this single email is mind-boggling.
While they don’t even specifically say which product they are using, no code I’ve ever been involved with or have my copyright use log4j and any rookie or better engineer could easily verify that.
In the picture version of the email I padded the name fields to better anonymize the sender, and in the text below I replaced them with NNNN.
(And yes, it is very curious that they send queries about log4j now, seemingly very late.)
Continue down for the reply.
The email
Dear Haxx Team Partner,
You are receiving this message because NNNN uses a product you developed. We request you review and respond within 24 hours of receiving this email. If you are not the right person, please forward this message to the appropriate contact.
As you may already be aware, a newly discovered zero-day vulnerability is currently impacting Java logging library Apache Log4j globally, potentially allowing attackers to gain full control of affected servers.
The security and protection of our customers' confidential information is our top priority. As a key partner in serving our customers, we need to understand your risk and mitigation plans for this vulnerability.
Please respond to the following questions using the template provided below.
1. If you utilize a Java logging library for any of your application, what Log4j versions are running?
2. Have there been any confirmed security incidents to your company?
3. If yes, what applications, products, services, and associated versions are impacted?
4. Were any NNNN product and services impacted?
5. Has NNNN non-public or personal information been affected?
6. If yes, please provide details of affected information NNNN immediately.
7. What is the timeline (MM/DD/YY) for completing remediation? List the NNNN steps, including dates for each.
8. What action is required from NNNN to complete this remediation?
In an effort to maintain the integrity of this inquiry, we request that you do not share information relating to NNNN outside of your company and to keep this request to pertinent personnel only.
Thank you in advance for your prompt attention to this inquiry and your partnership!
Sincerely,
NNNN Information Security
The information contained in this message may be CONFIDENTIAL and is for the intended addressee only. Any unauthorized use, dissemination of the information, or copying of this message is prohibited. If you are not the intended addressee, please notify the sender immediately and delete this message.
Their reply
On January 24th I received this response, from the same address and it quotes my reply so I know they got it fine.
Hi David,
Thank you for your reply. Are you saying that we are not a customer of your organization?
/ [a first name]
My second reply
I replied again (22:29 CET on Jan 24) to this mail that identified me as “David”. Now there’s this great story about a David and some giant so I couldn’t help myself…
Hi Goliath,
No, you have no established contract with me or anyone else at Haxx whom you addressed this email to, asking for a lot of information. You are not our customer, we are not your customer. Also, you didn't detail what product it was regarding.
So, we can either establish such a relationship or you are free to search for answers to your questions yourself.
I can only presume that you got our email address and contact information into your systems because we produce a lot of open source software that are used widely.
Best wishes,
Daniel
The image version of the initial email
The company
Update on February 9: The email came from MetLife.
The well-known log4j security vulnerability of December 2021 triggered a lot of renewed discussions around software supply chain security, and sometimes it has also been said to be an Open Source related issue.
This was not the first software component to have a serious security flaw, and it will not be the last.
What can we do about it?
This is the 10,000 dollar question that is really hard to answer. In this post I hope to help putting some light on to why it is such a hard problem. This comes from my view as an Open Source author and contributor since almost three decades now.
In this post I’m going to talk about security as in how we make our products have less bugs in the code we write and land on purpose. There is also a lot to be said about infrastructure problems such as consumers not verifying dependencies so that when malicious actors purposely destroy a component, users of that don’t notice the problem or supply chain security issues that risk letting bad actors insert malicious code into components. But those are not covered in this blog post!
The OSS Pyramid
I think we can view the world of software and open source as a pyramid, and I made this drawing to illustrate.
The OSS pyramid, click for bigger version.
Inside the pyramid there is a hierarchy where things using software are build on top of others, in layers. The higher up you go, the more you stand on the shoulders of open source components below you.
At the very bottom of the pyramid are the foundational components. Operating systems and libraries. The stuff virtually everything runs or depends upon. The components you really don’t want to have serious security vulnerabilities.
Going upwards
In the left green arrow, I describe the trend if you look at software when climbing upwards the pyramid.
Makes more direct money
Shorter lifetimes, faster iterations
Higher level languages
Shrinking share of Open Source
More end user facing
At the top, there are a lot of things that are not Open Source. Proprietary shiny fronts with Open Source machines in the basement.
Going downwards
In the red arrow on the right, I describe the trend if you look at software when going downwards in the pyramid.
Maintenance is more important than new fluff
Longer lifetimes
Bugs have larger impact, fixes take longer to get deployed
Lower level languages
At the bottom, almost everything is Open Source. Each component in the bottom has countless users depending on them.
It is in the bottom of the pyramid each serious bug has a risk of impacting the world in really vast and earth-shattering ways. That is where tightening things up may have the most positive outcomes. (Even if avoiding problems is mostly invisible unsexy work.)
Zoom out to see the greater picture
We can argue about specific details and placements within the pyramid, but I think largely people can agree with the greater picture.
Skyscrapers using free bricks
A little quote from my friend Stefan Eissing:
As a manufacturer of skyscrapers, we decided to use the free bricks made available and then maybe something bad happened with them. Where is the problem in this scenario?
Market economy drives “good enough”
As long as it is possible to earn a lot of money without paying much for the “communal foundation” you stand on, there is very little incentive to invest in or pay for maintenance of something – that also incidentally benefits your competitors. As long as you make (a lot of) money, it is fine if it is “good enough”.
Good enough software components will continue to have the occasional slip-ups (= horrible security flaws) and as long as those mistakes don’t truly hurt the moneymakers in this scenario, this world picture remains hard to change.
However, if those flaws would have a notable negative impact on the mountains of cash in the vaults, then something could change. It would of course require something extraordinary for that to happen.
What can bottom-dwellers do
Our job, as makers of bricks in the very bottom of the pyramid, is to remind the top brass of the importance of a solid foundation.
Our work is to convince a large enough share of software users higher up the stack that are relying on our functionality, that they are better off and can sleep better at night if they buy support and let us help them not fall into any hidden pitfalls going forward. Even if this also in fact indirectly helps their competitors who might rely on the very same components. Having support will at least put them in a better position than the ones who don’t have it, if something bad happens. Perhaps even make them avoid badness completely. Paying for maintenance of your dependencies help reduce the risk for future alarm calls far too early on a weekend morning.
This convincing part is often much easier said than done. It is only human to not anticipate the problem ahead of time and rather react after the fact when the problem already occurred. “We have used this free product for years without problems, why would we pay for it now?”
Software projects with sufficient funding to have engineer time spent on the code should be able to at least make serious software glitches rare. Remember that even the world’s most valuable company managed to ship the most ridiculous security flaw. Security is hard.
All producers of code should make sure dependencies of theirs are of high quality. High quality here, does not only mean that the code as of right now is working, but they should also make sure that the dependencies are run in ways that are likely to continue to produce good output.
This may require that you help out. Add resources. Provide funding. Run infrastructure. Whatever those projects may need to improve – if anything.
The smallest are better off with helping hands
I participate in a few small open source projects outside of curl. Small projects that produce libraries that are used widely. Not as widely as curl perhaps, but still millions and millions of users. Pyramid-bottom projects providing infrastructure for free for the moneymakers in the top. (I’m not naming them here because it doesn’t matter exactly which ones it is. As a reader I’m sure you know of several of this kind of projects.)
This kind of projects don’t have anyone working on the project full-time and everyone participates out of personal interest. All-volunteer projects.
Imagine that a company decides they want to help avoiding “the next log4j flaw” in such a project. How would that be done?
In the slightly larger projects there might be a company involved to pay for support or an individual working on the project that you can hire or contract to do work. (In this aspect, curl would for example count as a “slightly larger” kind.)
In these volunteers-only projects, all the main contributors work somewhere (else) and there is no established project related entity to throw money at to fix issues. In these projects, it is not necessarily easy for a contributor to take on a side project for a month or two – because they are employed to do something else during the days. Day-jobs have a habit of making it difficult to take a few weeks or months off for a side project.
Helping hands would, eh… help
Even the smallest projects tend to appreciate a good bug-fix and getting things from the TODO list worked on and landed. It also doesn’t add too much work load or requirements on the volunteers involved and it doesn’t introduce any money-problems (who would receive it, taxation, reporting, etc).
For projects without any existing way setup or available method to pay for support or contract work, providing man power is for sure a good alternative to help out. In many cases the very best way.
This of course then also moves the this is difficult part to the company that wants the improvement done (the user of it), as then they need to find that engineer with the correct skills and pay them for the allotted time for the job etc.
The entity providing such helping hands to smaller projects could of course also be an organization or something dedicated for this, that is sponsored/funded by several companies.
A general caution though: this creates the weird situation where the people running and maintaining the projects are still unpaid volunteers but people who show up contributing are getting paid to do it. It causes unbalances and might be cause for friction. Be aware. This needs to be done in close cooperating with the maintainers and existing contributors in these projects.
Not the mythical man month
Someone might object and ask what about this notion that adding manpower to a late software project makes it later? Sure, that’s often entirely correct for a project that already is staffed properly and has manpower to do its job. It is not valid for understaffed projects that most of all lack manpower.
Grants are hard for small projects
Doing grants is a popular (and easy from the giver’s perspective) way for some companies and organizations who want to help out. But for these all-volunteer projects, applying for grants and doing occasional short-term jobs is onerous and complicated. Again, the contributors work full-time somewhere, and landing and working short term on a project for a grant is then a very complicated thing to mix into your life. (And many employers actively would forbid employees to do it.)
Should you be able to take time off your job, applying for grants is hard and time consuming work and you might not even get the grant. Estimating time and amount of work to complete the job is super hard. How much do you apply for and how long will it take?
Some grant-givers even assume that you also will contribute so to speak, so the amount of money paid by the grant will not even cover your full-time wage. You are then, in effect, expected to improve the project by paying parts of the job yourself. I’m not saying this is always bad. If you are young, a student or early in your career that might still be perfect. If you are a family provider with a big mortgage, maybe less so.
In Nebraska since 2003
A more chaotic, more illustrative and probably more realistic way to show “the pyramid”, was done by Randall Munroe in his famous xkcd 2347 image, which, when applied onto my image looks like this:
Me shamelessly stealing image parts from xkcd 2347 to further make my point
Generalizing
Of course lots of projects in the bottom make money and are sufficiently staffed and conversely not all projects in the top are proprietary money printing business. This is a simplified image showing trends and the big picture. There will always be exceptions.
I’ve previously said that curl is one of the most widely used software components in the world with its estimated over ten billion installations, and I’m getting questions about it every now and then.
— Is curl the most widely used software component in the world? If not, which one is?
We can’t know for sure which products are on the top list of the most widely deployed software components. There’s no method for us to count or estimate these numbers with a decent degree of certainty. We can only guess and make rough estimates – and it also depends on exactly what we count. And quite probably also depending on who‘s doing the counting.
First, let’s acknowledge that SQLite already hosts a page for mostly deployed software module, where they speculate on this topic (and which doesn’t even mention curl). Also, does this count number of devices running the code or number of installs? If we count devices, does virtual machines count? Is it the number of currently used installations or total number of installations done over the years?
Choices
The SQLite page suggests four contenders for the top-5 list and I think it is pretty good:
zlib (the original implementation)
libpng
libjpeg
sqlite
I will go out on a limb and say that the two image libraries in the list, while of course very widely used, are not typically used on devices without screens and in the IoT world of today, such devices are fairly common. Light bulbs, power switches, networking gear etc. I think it might imply that they are slightly less used than the others in the list. Secondarily, libjpeg seems to not actually be around, but there are a few other successors that are used? Ie not a single implementation.
All top components are Open Source (sqlite’s situation is special but they still call it open source), and I don’t think it is a coincidence.
Are there other contenders not mentioned here? I figure maybe some of the operating systems for the tiniest devices that ship in the billions could be there. But I’m not sure there’s any such obvious market dominant player. There are other compression libraries too, but I doubt they reach the levels of zlib at this moment.
Someone brings up the Linux kernel, which certainly is very well used, but all Android devices, servers, windows 10 etc probably don’t make the unit count go over 7 billion and I believe that in virtually all Linux these kernel installs, curl, zlib and sqlite also run…
Similarly to how SQLite forgot to mention curl, I might of course also have a blind eye for some other really well-used code block.
The finalists
We end up with three finalists:
zlib
sqlite
libcurl
I think it is impossible for us to rank these three in an order with any good certainty. If we look at that sqlite list of where it is used, we quickly recognize that zlib and libcurl are deployed in pretty much all of them as well. The three modules have a huge overlap and will all be installed in billions of devices, while of course there are also plenty that only install one or two of them.
I just can’t figure out the numbers that would rank these modules in the top-list.
The SQLite page says: our best guess is that SQLite is the second mostly widely deployed software library, after libz. They might of course be right. Or wrong. They also don’t specify or explain how they do that guess.
libc
Whenever I’ve mentioned widely used components in the past, someone has brought up “libc” as a contender. But since there are many different libc implementations and they are typically done for specific platforms/operating systems, I don’t think any single of the libc implementations actually reach the top-5 list.
zlib in curl/sqlite
Many people says zlib, partly because curl uses it, but then I have to add that zlib is an optional dependency for curl and I know many, including large volume, users that ship products with libcurl that doesn’t use zlib at all. One very obvious and public example, is the curl.exeshipped in Windows 10 – that’s maybe one billion installs of curl that don’t bundle zlib.
If I understand things correctly, the situation is similar in sqlite: it doesn’t always ship with a zlib dependency.
The poll
I asked my twitter followers which one of these three components they guess is the most widely used one. Very unscientifically and of course skewed towards libcurl (since I asked and I have a curl bias),
The over 2,000 respondents voted libcurl with a fairly high margin.
The datestamp shown in the image is when the poll went up and it was online for 24 hours.
What did I miss?
Did I miss a contender?
Have I overlooked some stats that make one of these win?
Updates: Since this was originally posted, I have had OpenSSL, expat and the Linux kernel proposed to me as additional finalists and possibly most-used components.
On May 17, I joined the Kathy and Brian, the hosts of the GitHub ReadMe podcast on a video meeting from my home and we had a chat. Mostly about my work on curl. Today the episode “aired”.
curl is one of the most widely used software component in the world. It is over twenty years old and I am the founder and I still work as lead developer and head honcho. It works!
We talked about how I got into computers and open source in general. How curl started and about how it works to drive such a project, do releases and how to work on it as a full-time job. I am far from alone in this project – I’m just the captain of this ship with a large about of contributors onboard!
Photographs
As a part of the promotion for this episode, I was photographed by a professional outside of my house and nearby on a very lovely summer’s evening. In a southern suburb of Stockholm, Sweden. So, not only does the GitHub material feature not previously seen images of me, since I’ve been given the photos I can now use them for various things going forward. Like for when I do presentations and organizers ask for photos etc.
The photos I’ve used most commonly up until this point are the ones a professional photographer took of me when I spoke at the Velocity conference in New York in 2015. Of course I’m eternally young, but for some reason those past six years are visible on me…
Podcasts
I’ve participated in some podcasts before. If my count is correct, this is the 19th time. See the whole list.
Credits
The new set of photos of me were shot by Evia Photos. One of them is used on the top of this page.
It isn’t actually going away. It’s just been thrown over the fence to the Apache project and Subversion itself to host and maintain going forward.
Mail archive
When the Subversion project started in the early year 2000, I was there. I joined the project and participated in the early days of its development as I really believed in creating an “improved CVS” and I thought I could contribute to it.
While I was involved with the project, I noticed the lack of a decent mailing list archive for the discussions and set one up under the name svn.haxx.se as a service for myself and for the entire community. I had the server and the means to do it, so why not?
After some years I drifted away from the project. It was doing excellently and I was never any significant contributor. Then git and some of the other distributed version control systems came along and in my mind they truly showed the world how version control should be done…
The mailing list archive however I left, and I had even added more subversion related lists to it over time. It kept chugging along without me having to do much. Mails flew in, got archived and were made available for the world to search for and link to. Today it has over 390,000 emails archived from over twenty years of rather active open source development on multiple mailing lists. It is fascinating that no less than 46 persons have written more than a thousand emails each on those lists during these two decades.
Transition complete
The physical machine that runs the website is going to be shut down and taken out of service soon, and instead of just shutting down this service I’ve worked with the good people in the Subversion project and the hosting of that site and archive has now been taken over by the Apache project instead. It is no longer running on my machine. If you discover any issues with it, you need to talk to them.
Today, January 20 2021, I updated the DNS to instead have the host name svn.haxx.se point to Apache’s web server. I believe the plan is to keep the site as an archive of past emails and not add any new emails to it as of now.
I’m out
I hereby sign off my twenty years of service as an svn email archive janitor. It was a pleasure to serve you.
I founded the curl project early 1998 but had already then been working on the code since November 1996. The source code was always open, free and available to the world. The term “open source” actually wasn’t even coined until early 1998, just weeks before curl was born.
In the beginning of course, the first few years or so, this project wasn’t seen or discovered by many and just grew slowly and silently in a dusty corner of the Internet.
Already when I shipped the first versions I wanted the code to be open and freely available. For years I had seen the cool free software put out the in the world by others and I wanted my work to help build this communal treasure trove.
License
When I started this journey I didn’t really know what I wanted with curl’s license and exactly what rights and freedoms I wanted to give away and it took a few years and attempts before it landed.
The early versions were GPL licensed, but as I learned about resistance from proprietary companies and thought about it further, I changed the license to be more commercially friendly and to match my conviction better. I ended up with MIT after a brief experimental time using MPL. (It was easy to change the license back then because I owned all the copyrights at that point.)
To be exact: we actually have a slightly modified MIT license with some very subtle differences. The reason for the changes have been forgotten and we didn’t get those commits logged in the “big transition” to Sourceforge that we did in late 1999… The end result is that this is now often recognized as “the curl license”, even though it is in effect the MIT license.
The license says everyone can use the code for whatever purpose and nobody is required to ship any source code to anyone, but they cannot claim they wrote it themselves and the license/use of the code should be mentioned in documentation or another relevant location.
As licenses go, this has to be one of the most frictionless ones there is.
Copyright
Open source relies on a solid copyright law and the copyright owners of the code are the only ones who can license it away. For a long time I was the sole copyright owner in the project. But as I had decided to stick to the license, I saw no particular downsides with allowing code and contributors (of significant contributions) to retain their copyrights on the parts they brought. To not use that as a fence to make contributions harder.
Today, in early 2021, I count 1441 copyright strings in the curl source code git repository. 94.9% of them have my name.
I never liked how some projects require copyright assignments or license agreements etc to be able to submit code or patches. Partly because of the huge administrative burden it adds to the project, but also for the significant friction and barrier to entry they create for new contributors and the unbalance it creates; some get more rights than others. I’ve always worked on making it easy and smooth for newcomers to start contributing to curl. It doesn’t happen by accident.
Spare time
In many ways, running a spare time open source project is easy. You just need a steady income from a “real” job and sufficient spare time, and maybe a server to host stuff on for the online presence.
The challenge is of course to keep developing it, adding things people want, to help users with problems and to address issues timely. Especially if you happen to be lucky and the user amount increases and the project grows in popularity.
I ran curl as a spare time project for decades. Over the years it became more and more common that users who submitted bug reports or asked for help about things were actually doing that during their paid work hours because they used curl in a commercial surrounding – which sometimes made the situation almost absurd. The ones who actually got paid to work with curl were asking the unpaid developers to help them out.
I changed employers several times. I started my own company and worked as my own boss for a while. I worked for Mozilla on network stuff in Firefox for five years. But curl remained a spare time project because I couldn’t figure out how to turn it into a job without risking the project or my economy.
Earning a living
For many years it was a pipe dream for me to be able to work on curl as a real job. But how do I actually take the step from a spare time project to doing it full time? I give away all the code for free, and it is a solid and reliable product.
The initial seeds were planted when I met and got to know Larry (wolfSSL CEO) and some of the other good people at wolfSSL back in the early 2010s. This, because wolfSSL is a company that write open source libraries and offer commercial support for them – proving that it can work as a business model. Larry always told me he thought there was a possibility waiting here for me with curl.
Apart from the business angle, if I would be able to work more on curl it could really benefit the curl project, and then of course indirectly everyone who uses it.
It was still a step to take. When I gave up on Mozilla in 2018, it just took a little thinking before I decided to try it. I joined wolfSSL to work on curl full time. A dream came true and finally curl was not just something I did “on the side”. It only took 21 years from first curl release to reach that point…
I’m living the open source dream, working on the project I created myself.
Food for free code
We sell commercial support for curl and libcurl. Companies and users that need a helping hand or swift assistance with their problems can get it from us – and with me here I dare to claim that there’s no company anywhere else with the same ability. We can offload engineering teams with their curl issues. Up to 24/7 level!
We also offer custom curl development, debugging help, porting to new platforms and basically any other curl related activity you need. See more on the curl product page on the wolfSSL site.
curl (mostly in the shape of libcurl) runs in ten billion installations: some five, six billion mobile phones and tablets – used by several of the most downloaded apps in existence, in virtually every website and Internet server. In a billion computer games, a billion Windows machines, half a billion TVs, half a billion game consoles and in a few hundred million cars… curl has been made to run on 82 operating systems on 22 CPU architectures. Very few software components can claim a wider use.
“Isn’t it easier to list companies that are not using curl?”
Wide use and being recognized does not bring food on the table. curl is also totally free to download, build and use. It is very solid and stable. It performs well, is documented, well tested and “battle hardened”. It “just works” for most users.
Pay for support!
How to convince companies that they should get a curl support contract with me?
Paying customers get to influence what I work on next. Not only distant road-mapping but also how to prioritize short term bug-fixes etc. We have a guaranteed response-time.
You get your issues first in line to get fixed. Customers also won’t risk getting their issues added the known bugs document and put in the attic to be forgotten. We can help customers make sure their application use libcurl correctly and in the best possible way.
I try to emphasize that by getting support from us, customers can take away some of those tasks from their own engineers and because we are faster and better on curl related issues, that is a pure net gain economically. For all of us.
This is not an easy sell.
Sure, curl is used by thousands of companies everywhere, but most of them do it because it’s free (in all meanings of the word), functional and available. There’s a real challenge in identifying those that actually use it enough and value the functionality enough that they realize they want to improve their curl foo.
Most of our curl customers purchased support first when they faced a complicated issue or problem they couldn’t fix themselves – this fact gives me this weird (to the wider curl community) incentive to not fix some problems too fast, because it then makes it work against my ability to gain new customers!
We need paying customers for this to be sustainable. When wolfSSL has a sustainable curl business, I get paid and the work I do in curl benefits all the curl users; paying as well as non-paying.
Dual license
There’s clearly business in releasing open source under a strong copyleft license such as GPL, and as long as you keep the copyrights, offer customers to purchase that same code under another more proprietary- friendly license. The code is still open source and anyone doing totally open things can still use it freely and at no cost.
We’ve shipped tiny-curl to the world licensed under GPLv3. Tiny-curl is a curl branch with a strong focus on thetiny part: the idea is to provide a libcurl more suitable for smaller systems, the ones that can’t even run a full Linux but rather use an RTOS.
Consider it a sort of experiment. Are users interested in getting a smaller curl onto their products and are they interested in paying for licensing. So far, tiny-curl supports two separate RTOSes for which we haven’t ported the “normal” curl to.
Keeping things separate
Maybe you don’t realize this, but I work hard to keep separate things compartmentalized. I am not curl, curl is not wolfSSL and wolfSSL is not me. But we all overlap greatly!
The Daniel + curl + wolfSSL trinity
I work for wolfSSL. I work on curl. wolfSSL offers commercial curl support.
Reserved features
One idea that we haven’t explored much yet is the ability to make and offer “reserved features” to paying customers only. This of course as another motivation for companies to become curl support customers.
Such reserved features would still have to be sensible for the curl project and most likely we would provide them as specials for paying customers for a period of time and then merge them into the “real” open source curl project. It is very important to note that this will not in any way make the “regular curl” worse or a lesser citizen in any way. It would rather be a like a separate product, a curl+ with extra stuff on top of vanilla curl.
Since we haven’t ventured into this area yet, we haven’t worked out all the details. Chances are we will wander into this territory soon.
Other food-generators
I do occasional speaking gigs on curl and HTTP related topics but even if I charge for them this activity never brings much more than some extra pocket money. I do it because it’s fun and educational.
It has been suggested that I should create a web shop to sell curl branded merchandise in, like t-shirts, mugs, etc but I think that grossly over-estimates the user interest and how much margin I could put on mundane things just because they’d have a curl logo glued on them. Also, I would have a difficult time mentally to sell curl things and claim the profit personally. I rather keep giving away curl stash (mostly stickers) for free as a means to market the project and long term encourage users into buying support.
Donations
We receive money to the curl project through donations, most of them via our opencollective account. It is important to note that even if I’m a key figure in the project, this is not my money and it’s not my project. Donated money is spent on project related expenses, which so far primarily is our bug bounty program. We’ve avoided to spend donated money on direct curl development, and especially such that I could provide or benefit from myself, as that would totally blur the boundaries. I’m not ruling out taking that route in a future though. As long as and only if it is to the project’s benefit.
Donations via GitHub to me personally sponsors me personally and ends up in my pockets. That’s not curl money but I spend it mostly on curl development, equipment etc and it makes me able to not have to think twice when sending curl stickers to fans and friends all over the world. It contributes to food on my table and I like to think that an occasional beer I drink is sponsored by friends out there!
The future I dream of
We get a steady number of companies paying for support at a level that allows us to also pay for a few more curl engineers than myself.
I started learning how to program in my teens, well over thirty years ago and I’ve worked as a software engineer and developer since the early 1990s. My first employment as a developer was in 1993. I’ve since worked for and with lots of companies and I’ve worked on a huge amount of (proprietary) software products and devices over many years. Meaning: I certainly didn’t start my life open source. I had to earn it.
When I was 20 years old I did my (then mandatory) military service in Sweden. After having endured that, I applied to the university while at the same time I was offered a job at IBM. I hesitated, but took the job. I figured I could always go to university later – but life took other turns and I never did. I didn’t do a single day of university. I haven’t regretted it.
I learned to code in the mid 80s on a Commodore 64 and software development has been one of my primary hobbies ever since. One thing it taught me well, that I still carry with me, is to spend a few hours per day in front of my home computer.
And then I shipped curl
In the spring of 1998 I renamed my little pet project of the time again and I released the first ever curl release. I have told this story many times, but since then I have spent two hours or so of my spare time on that project – every day for over twenty years. While still working as a software engineer by day.
Over time, curl gradually grew popular and attracted more users. There was no sudden moment in time where I struck gold and everything took off. It was just slowly gaining ground while me and my fellow project members kept improving and polishing curl. At some point in time I happened to notice that curl and libcurl would appear in more and more acknowledgements and in open source license collections in products and devices.
It was still just a spare time project.
Proprietary Software for years
I’d like to emphasize that I worked as a contract and consultant developer for many years (over 20!), primarily on proprietary software and custom solutions, before I managed to land myself a position where I could primarily write open source as part of my job.
Mozilla
In 2014 I joined Mozilla and got the opportunity to work on the open source project Firefox for a living – and doing it entirely from my home. This was the first time in my career I actually spent most of my days on code that was made public and available to the world. They even allowed me to spend a part of my work hours on curl, even if that didn’t really help them and curl was not a fundamental part of any Mozilla work or products. It was still great.
I landed that job for Mozilla a lot thanks to my many years and long experience with portable network coding and running a successful open source project at this level.
My work setup with Mozilla made it possible for me to spend even more time on curl, apart from the (still going) two daily spare time hours. Nobody at Mozilla cared much about (my work with) curl and no one there even asked me about it. I worked on Firefox for a living.
For anyone wanting to do open source as part of their work, getting a job at a company that already does a lot of open source is probably the best path forward. Even if that might not be easy either, and it might also mean that you would have to accept working on some open source projects that you might not yourself be completely sold on.
In late 2018 I quit Mozilla, in part because I wanted to try to work with curl “for real” (and part other reasons that I’ll leave out here). curl was then already over twenty years old and was used more than ever before.
wolfSSL
I now work for wolfSSL. We sell curl support and related services to companies. Companies pay wolfSSL, wolfSSL pays me a salary and I get food on the table. This works as long as we can convince enough companies that this is a good idea.
The vast majority of curl users out there of course don’t pay anything and will never pay anything. We just need a small number of companies to do it – and it seems to be working. We help customers use curl better, we make curl better for them and we make them ship better products this way. It’s a win win. And I can work on open source all day long thanks to this.
My open source life-style
A normal day in the work week, I get up before 7 in the morning and I have breakfast with my family members: my wife and my two kids. Then I grab my first cup of coffee for the day and take the thirteen steps up the stairs to my “office”.
I sit down in front of my main development (Linux) machine with two 27″ screens and get to work.
Photo of my work desk from a few years ago but it looks very similar still today.
What work and in what order?
I lead the curl project. It means many questions and decisions fall down to me to have an opinion about or say on, and it’s a priority for me to make sure that I unblock such situations as soon as possible so that developers wanting to do things with curl can continue doing that.
Thus, I read and respond to email about curl all hours I’m awake and have network access. Of course incoming messages actually rarely require immediate responses and then I can queue them up and instead do them later. I also try to read and assess all new incoming curl issues as soon as possible to see if there’s something urgent I should deal with immediately, or otherwise figure out how to deal with them going forward.
I usually have a set of bugs or features to work on so when there’s no alarming email or GitHub issue left, I context-switch over to the curl source code tree and the particular branch in which I work on right now. I typically have 20-30 different branches of development of various stages and maturity going on. If I get stuck on something, or if I create a pull-request for one of them that needs time to get all the CI jobs done, I switch over to one of the others.
Customers and their needs of course have priority when I decide what to work on. The exception would perhaps be security vulnerabilities or other really serious bugs being reported, but thankfully they are rare. But after that, I go by ear and work on what I think is fun and what I think users might appreciate.
If I want to go forward with something, for my own sake or for a customer’s, and that entails touching or improving other software in other projects, then I don’t shy away from submitting pull requests for them – or at least filing an issue.
Spare time open source
Yes, I still spend my spare time hours on open source, mostly curl. This means I often end up spending 50-55 hours per week on curl and curl related activities. But I don’t count or measure work hours and I rarely have to report any to anyone. This is a work of love.
Lots of people will say that they don’t have time because of life, family, kids etc. I have of course been very fortunate over the years to have had the opportunity and ability to spend all this time on what I want to do, but let’s not forget that people in general spend lots of time on their hobbies; on watching TV, on playing computer games and on socializing with friends and why not: to sleep. If you cut down on all of those things (yes, including the sleeping) there could very well be opportunities. It’s often a question of priorities. I’ve made spare time development a priority in my life.
curl support?
Any company that uses curl or libcurl – and they are plenty – could benefit from buying support from us instead of wasting their own time and resources. We at wolfSSL are probably much better at curl already and we can find and fix the issues much faster, which ends up cheaper and better long-term.
Credits
The top photo is taken by Anja Stenberg, my wife. It’s me in a local forest, summer 2020.
