The public W3C XML Schema homepage [1] lists a number of free validators.
Several of them have online form-based interfaces as well as
downloads.
ht
[1]
http://www.w3.org/XML/Schema.html
--
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
Half-time member of W3C Team
2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
Fax: (44) 131 650-4587, e-mail:
URL:
http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]