For many years Ibuildings has had a formalized way of reviewing people’s skill sets. This system enables tracking of skills and relative changes in those skills over the years, across the organization. This has been used as a means for estimating a person’s salary and appropriate changes to it, as well as opportunities for personal development.
In early 2016 we recognized that the technical part of this system needed an update. So I started working on a new list of technical skills.


The goal was to describe what developers at Ibuildings need to know and be capable of in order to be successful web application developers. I was looking for a way to consistently describe these skills. While brainstorming and mindmapping the new list of technical skills, I had several key thoughts, which helped shape the list:

  • Every developer evolves in different ways and in different directions. Hence, everyone has a different skill set at any given time. The list of technical skills should therefore by no means be used as a mold into which every developer should be forced.
  • The list of skills should have an expiration date of at least several years. This means that it should not contain too many specific technologies that might be “in vogue” now, but become irrelevant next year (like frameworks, tools and even programming languages). So even though the standard web application development framework at Ibuildings is Symfony, you won’t find anything about it in the list of skills, since it’s not the particular framework, but the concepts behind it that matter for the overall skill set of a developer.
  • It’s impossible to adequately assess most of the skills I had in mind. In most cases a topic is so broad, and so deep, that you could write a book about it, have years of experience with it, and still feel that there’s room for exploration and improvement.

Based on the structure of the system that was already in place, I decided that the outline of each skill on the list should be something like this:

  1. A specific topic, probably nested inside some hierarchical structure of chapters, e.g. “Test doubles”, under “Coding - Testing - Unit testing”.
  2. A description of the skill or knowledge a developer should have on this subject, e.g. “Knows the differences between different kinds of test doubles, like mocks, stubs, dummies, spies, etc.”.
  3. The type of answer the assessor would have to write down: yes/no or some scale.
  4. Topics to be discussed with the developer, which reveal the depth of their knowledge or experience, like possible points of disagreement, alternative perspectives, etc. For example: “Discuss: does it matter how many times a method will be called, are all the actual arguments important, is the exact return value important, etc.”.
  5. Relevant reference materials, like book titles or web pages, e.g. “Reference material: Test Double bliki.

Most topics on the list would be really hard to assess simply by writing down a “yes” or a “no” for each developer. There are often different levels of understanding and experience with regard to any topic. So for these topics we use a scale: a developer can score 1 to 4 points on these. The points correspond to the following stages (think for example of “Event sourcing” as a topic/skill while reading the following list):

  1. In the first stage, you’ve never heard of it or have only heard it mentioned, yet never looked it up.
  2. In the second stage, you’ve looked it up, you know what it is, and when you would need it.
  3. Now, you’ve also applied the concept in a real life situation, e.g. in a production application.
  4. Finally, you enter a stage where, compared to other team members, you have more experience with this topic. This results in you coaching others on this topic.


I had wanted to try out Mindmup and it seemed to be a perfect fit for what I was going to do: create a mindmap of all the technical skills and knowledge I thought would be “required” for web application developers. Mindmup turned out to be a very useful tool (in particular version 2). It’s very easy to add notes to each element of the mindmap too.

The resulting tree that I created looks something like this: The technical skills tree

I found that for some developers this was a daunting view, but for many it was inspiring too. It showed several interesting future directions (that weren’t mentioned in the previous version of the technical skills list).

Because I wanted to create a readable, printable document containing the topics in the skills tree as well as the interview questions, I had to do some reverse engineering based on the output format of Mindmup. A .mup file (which can be exported from the web app) appeared to be just a JSON file. Its structure is relatively simple. So I wrote a CLI script (with some supporting classes of course) that takes apart the .mup file and converts its tree structure to a flattened document.

Since I used Markdown in the notes for each node in the tree I used a Markdown converter to convert the notes to HTML. The intermediate result is an HTML file, which then gets converted to PDF using wkhtmltopdf.


I’m proud to share with you now the full technical skills tree. I think it provides a nice overview of which skills are needed for current web application development (with a strong focus on the back-end). The colours yellow, orange and red correspond to¬†experience levels of programmers (roughly: junior, medior, senior). For example, “Messaging integration” has a red label, which means that we only expect senior programmers to have experience with this subject.

Please note that while I’ve tried to make this a more or less objective list, it will (of course) reveal some personal interests and preferences as well. But I think that in case you want to use this list of skills in your company, you’ll revise it anyway. If you do so, you’re encouraged (not obligated) to share your results and modifications with the community too.