I am looking for an open-source software that would help me understand source code faster. I am aware of tools like Understand, Source Insight, etc., but they are commercial with hefty fees for a license.

The software should be easy to use, should provide a graphical depiction of the functions, data structures etc. and should allow me to change variable names and add comments within the software itself.

  • Platform: Windows or Linux. Plugins to IDEs are also fine.
  • Languages supported: C++ and Java, anything in addition to this is a plus.

The software should work well with large source codes like those of Linux.

  • 3
    SonarQube might also be something for you. I didn't use it much, so I haven't got enough knowledge to recommend it. – Thomas Weller Apr 27 '16 at 20:52
  • Have you tried OpenGrok? Setting it up is relatively easy. vineelkumarreddy.com/2015/04/29/… – Vineel Kovvuri Dec 26 '17 at 20:22
  • Just for others: CodeScene is another commercial product. It aim is to also understand the team and the communication paths behind the code by analyzing the commit history. – Thomas Weller Jun 26 '18 at 14:32

All in all, I'd say your wish list for a gratis tool like that is quite long. In the last company I worked for, I was responsible for the maintenance of projects and I made myself familiar with metrics and code quality analysis. Below information is given on my knowledge of ~2 years ago. The only free tool I found that roughly matches your requirements is

ConQAT, the Continuous Quality Analysis Tool.


  • analyzes Java, C++, C#, ABAP, ADA
  • is gratis (Apache 2)
  • integrates in Eclipse, so you can rename variables etc. as usual
  • allows for analysis of architectural constraints and code clones
  • works at least on Windows, not sure about Linux. It's Java-based, so it might work there as well if you don't need C# support.


  • easy to use: well, it depends on what "easy" means for you. The metrics are built with a GUI, so basically, yes. You should have knowledge of metrics, though.
  • graphical depiction of the functions: not something like IDA Pro, but e.g. with treemaps. It can also visualize the architecture at least down to class level.
  • large source codes: I have no clue how large the source code of Linux is. It worked fine on a C# project with 130k LOC

Other notes (based on information 2 years ago):

  • The tool is updated in irregular intervals, although the version numbering system suggests that there are 2 releases per year.
  • It's hard to get support, unless you're willing to pay for it. I did not find a "community" that would answer questions.
  • You can implement own information providers in Java.

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