Diaphora (διαφορά, Greek for 'difference') is a program diffing plugin for IDA Pro, similar to Zynamics Bindiff or the FOSS counterparts DarunGrim, TurboDiff, etc... It was released during SyScan 2015.
At the moment, it works with IDA Pro but support for Radare2 (and maybe Pyew or even Hopper) is also planned. For more details, please check the tutorial in the "doc" directory.
Getting help and asking for features
You can join the mailing list https://groups.google.com/forum/?hl=es#!forum/diaphora to ask for help, new features, report issues, etc... For reporting bugs, however, I recommend using the issues tracker: https://github.com/joxeankoret/diaphora/issues
Please note that only the last 2 versions of IDA will be supported. As of today, it means that only 6.7 and 6.8 are supported. Version 6.6 "should work" (with all the last patches that were supplied to customers), but no support is offered for it.
You can check the tutorial https://github.com/joxeankoret/diaphora/blob/master/doc/diaphora_help.pdf
This is a screenshot of Diaphora diffing the PEGASUS iOS kernel Vulnerability fixed in iOS 9.3.5:
And this is an old screenshot of Diaphora diffing the Microsoft bulletin MS15-034: