GitHub Heatmaps

Dear hiring managers, it's time to talk about your favorite criterion for selecting software developers – that lovely, colorful little grid on GitHub known as a heatmap. It’s an attractive matrix, filled with hues of green depicting user activity and implying productivity. It is a kaleidoscope of contribution chaos, and you, in all your infinite wisdom, might see it as the magical map to your next top-tier talent.

The GitHub heatmap illusion

I hate to be the bearer of bad news, but I think it’s time to start viewing that similar to how you'd view someone stating that they're a professional golf player on a software developer application. It's not entirely irrelevant because it does indeed tell you more about the person, but it's also not something you'd base your final decision on. The GitHub heatmap is not the Holy Grail of developer evaluation, and there are numerous reasons why it's a terrible idea to measure productivity or gauge the performance of a developer.

The heatmap displays the number of contributions a user has made in public repositories, offering a delightful play of lighter and darker greens. However, the critical word here is "public." Many developers work on private repositories for their companies or personal projects, which don't show up on the heatmap. Thus, if you're under the impression that a developer isn't working unless their heatmap is lit up like a Christmas tree, well, you're just wrong.

Inherent limitations of public repositories

On a different note, when I was starting to work with GitHub, there were occasions where I messed up Git so badly that it just made more sense to rm -rf that hidden .git directory. With that, my precious green squares disappeared. This XKCD captures it well. I also try to spend a lot of my time doing things that just don't make sense to make public – exploring new frameworks, playing around with new libraries, quickly prototyping things that I just want to try out, and so on. If I assume that a hiring manager will be looking at my public repos, I'm not going to make those public because that kind of code is not of very high quality by default.

Misinterpretations of contribution quantity

Secondly, the number of contributions does not equate to quality or complexity. A developer might have a single commit where they solved a complex algorithm that revolutionized the user experience of an application. In contrast, another may have fifty commits adjusting the color scheme of a webpage. Using the heatmap to gauge a developer's skills is like using a sundial to measure the speed of a Ferrari – it's just not built for that purpose.

Does the notion of "work-life balance" ring a bell? Developers are humans, not machines (shocking revelation, I know). They have lives beyond their screens. If you are looking for a developer who is active on GitHub seven days a week, you may also be looking for burnout, decreased job satisfaction, and potential loss of a valuable team member in the future. Code quality tends to deteriorate with exhaustion, so an empty square on a Sunday does not make a developer lazy; it makes them balanced.

Learning and growth beyond open source contributions

Remember also that open-source contributions aren't the only way developers learn and grow. Maybe they're busy attending conferences, reading technical papers, doing courses, or contributing to internal projects. GitHub has yet to find a way to illustrate personal growth and knowledge sharing through pretty green squares, but I don't blame them for it. It's not GitHub's job to do that, but yours.

Lastly, it is essential to remember that not every developer is a GitHub user. It may be hard to imagine, but there are developers who prefer GitLab, Bitbucket, or even dare I say, not using a version control system at all. They may be missing out on the spectacular beauty of a heatmap, but they might also be good at what they do.

A well-rounded evaluation involves looking at a person's problem-solving skills, understanding of algorithms and data structures, collaborative nature, eagerness to learn, and so much more. Coding is an art as much as a science, and it's intellectually dishonest to think that you can sum a developer's worth by their GitHub heatmap.

Final thoughts

Code is not judged by the quantity of commits, but by the quality of solutions. So, the next time you gaze lovingly at a GitHub heatmap, remember that there's a lot more to a developer than meets the eye.