The MathOverflow question Open source mathematical software contains a list of programs that are useful to perform various computational tasks, such as computer algebra systems.

However, evaluating complicated formulas is not all that a professional mathematician needs to do. For instance, another important part of it is *communicating* results, producing papers and slides. There was a Mathoverflow question devoted specifically to
tools for collaborative paper writing.

It would be useful to identify and gather on MO a list of **areas of activities** where research mathematicians can use software as part of their professional activity.

I think it would also be useful to gather on MO a list of **software** that does not strictly do *computations*, but is nevertheless useful to those who research and teach mathematics.

The first example that springs to mind is of course $\LaTeX$, but there is much more:

- citation and literature management software, such as Jabref, Zotero, Mendeley
- conference management software, such as Open Conference Systems (never actually used it, but it seems interesting)
- reference tools such as the Online Encyclopedia of Integer Sequences and Plouffe's Inverter
- Euclidean geometry software such as Geogebra
- diff'ing and merging tools, such as latexdiff, kdiff3
- specific LaTeX packages such as Beamer for presentations or several drawing packages (TikZ, Eukleides).

I find some of those real gems, and I'd like to find out more examples. So, the question is:

Can you provide (other) examples of programs that are useful to professional mathematicians in their job, while not being strictly speaking "software that does complicated computations"?

The question is a little broad and perhaps if there is much software relevant to a specific activity it will be wise to ask, based on input given to the question, a more specific question. Also please do not interpret this question too broadly (see discussion below).

Also check these MO questions: Tools for collaborative paper-writing (mainly regarding revision control software), Most helpful math resources on the web (mainly regarding online databases of something).