Portable, free, cross-platform, GUI-based prose-friendly plain-text diff and merge tool?

Question

I have a Macbook at home and a GNU/linux desktop workstation at work. But, I sometimes also have to work on my university's library machines (running Windows 7) without admin rights.

Is there a (preferably open-source), but certainly free (as in free beer), cross-platform GUI-based plain-text diff-tool that will work on at least these three platforms (Win 7 & 10, GNU Linux, MacOS 10.13)? For Windows machines, this must work without admin priveleges.

Viable option until now: VimDiff

I did an exhaustive research of options before posting this question. The only viable tool I could find was vimdiff (i.e. the diff-mode within vim) that truly satisfies all criteria (GUI available, free, open-source, cross-platform). The amazing fugitive.vim plugin by the legendary tpope also brings in git-based diff and 3-way merging to within vim. Now, while I am very comfortable with vim, since I need to also work on friends' machines to view diffs on a collaborative project, I do not want to force them to learn vim. Furthemore, since we are presently working on prose (a paper being written in latex) rather than code, I think a word-based diff-tool, rather than a line-based one shall be helpful.

Possible cue: Java based

A majority of machines I work on have a working JRE installed. So, even if a true multi-platform native desktop application is not available, an app distributed as a portable jar file which runs atop a standard JVM/JRE should be good enough. I found jedit which has a diff plugin. But even this asks for an install to the restricted C:\program_files(x86) location on Windows. I am looking for something which works akin to jabref which is a brilliant reference management software distributed as a cross-platform standalone jar file.

Possible cue2: Tcl/Tk based alternatives

The TCL/TK framework seems to be yet another way to go portable. I found tkdiff which seems to be well-maintained. But, my univeristy's library machines do not have TCL/TK framework installed on Win 7. I tried clicking around freewrap but cannot figure out how to use it. Any help in this direction is also welcome.

Note on web-based alternatives

prettydiff is a viable browser-based alternative that ticks all required boxes. But since we do not like to upload any source-component of our project on the web (despite any privacy promises), a standalone desktop application becomes essential. Such web-based tools cannot also handle git repos, and is good for just a quick one-off diff, rather than as part of a systematic workflow.

PS: Git or other vcs-diff capabilities will be a bonus.

Answer 1

PrettyDiff is CC0 licensed -

"Pretty Diff project, as of version 2.1.17 and all following versions unless otherwise changed, is licensed with a Creative Commons 1.0 Universal license (CC0)."

Why not grab source and run it on your own machine or on a VPS?

Website: http://prettydiff.com/

GitHub: https://github.com/prettydiff/prettydiff

Answer 2

I use Diffuse. From the "About" page:

Diffuse is a small and simple text merge tool written in Python.

Diffuse should run on any POSIX operating system, including Mac OS X, with the following packages installed:

Python >= 2.4
PyGTK >= 2.10

Pre-built packages for Microsoft Windows include all dependencies.

Development has stopped in 2014, though.

Answer 3

When I need portability I generally look to perl. For example, on a Mac:

$ head z1 z2 ; ./diff.pl z1 z2
==> z1 <==
hi

==> z2 <==
bye
1c1
< hi
---
> bye

Here are some details:

diff.pl Display differences in text files, perl version. (what)
Path    : ~/bin/diff.pl
Version : - ( local: ~/bin/diff.pl, 2009-10-22 )
Length  : 729 lines
Type    : Perl script, ASCII text executable
Shebang : #!/usr/bin/perl
Modules : (for perl codes)
 strict 1.08
 Carp   1.3301
 Algorithm::Diff        1.1902

On a system like:

OS, ker|rel, machine: Apple/BSD, Darwin 17.6.0, x86_64
Distribution        : macOS 10.13.5 (17F77), High Sierra
diff.pl - ( local: ./diff.pl, 2018-07-01 )

And diff.pl can be found at cpan.org: perl version of diff You'll need perl on Windows; I have not tried that recently.

Best wishes ... cheers, drl