Sage is an open source collection of mathematical software with a common Python interface. The lead developer is William Stein, a number theorist in the Mathematics Department at the University of Washington.

The Sage notebook was an original model for the *IPython_notebook*.

You can try Sage online by typing into a cell at https://sagecell.sagemath.org/. You can type straight Python as well as using the enhanced capabilities of Sage.

See:

for some online sage examples.