pyang (v. 0.9.2 2008-10-13, draft-ietf-netmod-yang-01 compatible) is an extensible YANG validator written in Python. It can be used standalone as a validator, to generate YIN, YANG, DSDL and XSD from YANG and YIN. It can also be integrated in some other application, which e.g. can generate vendor-specific stub code.
yang-mode.el is an emacs mode for editing YANG files. draft -02 compliant. Requires cc-mode 5.30 or later.
yangto (v. 0.8.4 2008-03-07, draft-02 compatible) is a YANG validator and translator, available in binary format. There are currently 2 distributions supported, with more available soon: Fedora-8 i386 binary MacOS-X Intel binary Man page (HTML) (nroff)