When I (in spite of knowing better) talk to ordinary people about what I do for a living and the project I work on, one of the details about it that people have the hardest time to comprehend, is the fact that I really and truly don’t know a lot about who uses my code. (Or where. Or what particular features they use.)

I work on curl full-time and we ship releases frequently. Users download the curl source code from us, build curl and put it to use. Most of “my” users never tell me or anyone else in the curl project that they use curl or libcurl. This is of course perfectly fine and I probably could not even handle the flood if every user would tell me.

This not-knowing is a most common situation for Open Source authors and projects. It is not unique for me.

The not knowing your users is otherwise unusual in a world of products and software, and quite frankly, sometimes it is an obstacle for us as well since we lack a good way to communicate with users about plans, changes or ideas. It also makes it really hard to estimate our own success and the always-recurring question: how many users do you have?

To be fair: I do know quite a lot of users as well. But I don’t know how representative they are, nor how big fraction of the totals they consist of etc.

How to find out that someone uses your code

I wrote a section in Uncurled about How to find out that someone uses your code, and these are three main ways I learn about users of my code:

1. A user of my project runs into an issue and asks for help in a project forum – without hiding where they come from or what product they make.
2. While vanity-searching I find my project’s Open Source license mentioned for or bundled with a product or tool or device.
3. A user emails me asking funny questions about a product I never heard of, and then I realize they found my email because that product uses my code and the license has my email in it.