The new Cadabra is here
The old Cadabra site at cadabra.phi-sci.com has been disabled, and all information about Cadabra, in particular the new 2.x series, can be found here. This page lists some things about the 1.x release which may still be relevant for its current users.
The new Cadabra 2.x series is a rewrite and extension of the old 1.x series, which first saw the light in 2007. Many things have changed and improved. This page tells you what you need to know about the differences. Unless you have old 1.x notebooks which you need to run, you are strongly encouraged to try installing 2.x. Support for 1.x will not go away, but there will be no more improvements, only bug fixes.
Getting the software
Version 1.x is available in many Linux distributions and on MacPorts, and has just been accepted for the new Debian release, so it will continue to be available for some time to come. Version 2.x is still undergoing many rapid changes, so it is at the moment not yet available in any distributions. Instead, you can get it directly from this web site's download page, in the form of various packages for Linux distributions. On Mac OS X you need to build from source, but this is a fairly painless procedure thanks to the magic of Homebrew.
You can install 1.x and 2.x on the same system without any clashes, so you can continue to work with 1.x and at the same time get used to 2.x.
I will no longer provide source tarballs for 1.x, but you can easily get the source from the Cadabra 1.x github repository.
The new 2.x notebooks are not compatible with the old 1.x notebooks, and you can not (yet?) read old notebooks into the new version. The main reason for not providing backward compatibility is that there have been many changes in the input format, and writing a converter takes time. However, if you have large 1.x notebooks that you would really like to auto-convert, get in touch and we'll see what we can do.