HTMLcheck is a freeware program for RISC OS computers. It validates HTML files using a port of the sgmls SGML parser.
The current version of HTMLcheck is 1.12, which can be obtained from here.
Version 1.10 and above ia a 26/32 bit neutral application, which means that it requires a 32 bit compatible bersion of the Shared C Library to be installed. If you do not already have this then you can download it here.
Please note that the DDEUtils and Frontend modules provided with the Acorn/Castle software development environment are needed for the desktop part of this package to work. These modules are also available from the above location, although they are only in the full (TBox.zip) archive.