Question: hello.

I am looking for tensor manipulation software that would allow me:

* declare indices
* declare results of contraction (or simplification rules)
* allow algebraic simplifications and expansion
* index renaming

So far I have found Maxima to satisfy my requirement more or less, <http://maxima.sourceforge.net/docs/manual/en/maxima_27.html> 

one last thing I also want, (but not necessarily require), is interface with python.
In principle I could use sage to interface with maxima.

Is there some other Cas that has package with similar tensor
manipulation properties?

from links given below, I also found this, <http://cadabra.phi-sci.com/>, which looks geared specifically for tensor manipulations.

Answer: 
I think that everything in your list (except the Python interface) can be found in Kasper Peeters' [Cadabra](http://cadabra.phi-sci.com/). 

As for a Python interface, there are two directions:

1. [It is planned](http://cadabra.phi-sci.com/ideas.html) to add an interface layer to Cadabra to either Maxima or SymPy - in the latter case you'd probably get access to Python.
2. [There is talk](http://groups.google.com.au/group/sage-devel/browse_thread/thread/83182fbfc62cd0f6/3623f8d9d819c01c?q=Cadabra+interface#3623f8d9d819c01c) of adding a Cadabra interface to sage using the standard sage.interfaces.expect class.

As an aside some of the index algorithms come from José Martin-Garcia's [xPerm](http://metric.iem.csic.es/Martin-Garcia/xAct/index.html), a Mathematica package. xPerm seems to be more suited to GR while Cadabra is focused on QFT.
[FORM](http://www.nikhef.nl/~form/) (the successor of Schoonschip) is also very powerful and used in a lot of high energy physics computing.
I think your best bet is a physics oriented package which I think is just called R or maybe Reduce. Meanwhile, here is the msri page of documentation for most packages currently available there.
<http://www.msri.org/about/computing/mathdocs>
$$ $$
<http://en.wikipedia.org/wiki/FORM_(symbolic_manipulation_system)>
$$ $$
<http://en.wikipedia.org/wiki/List_of_computer_algebra_systems>