Links
The Stacks project
An open source textbook and reference work on algebraic goemetry that necessarily includes a lot of fundamental results in commutative algebra.
Macaulay2Web
Browser-based interface to the Macaulay2 open source software system devoted to supporting research in algebraic geometry and commutative algebra.
Magma calculator
Online calculator that provides (compute-limited) access to the Magma computer algebra system, which includes substantial support for commutative algebra.
