<p>I need to convert HTML documents into valid XML, preferably XHTML. What's the best way to do this? Does anybody know a toolkit/library/sample/...whatever that helps me to get that task done?</p>

<p>To be a bit more clear here, my application has to do the conversion automatically at runtime. I don't look for a tool that helps me to move some pages to XHTML manually.</p>

Convert from HTML to XML with HTML Tidy
Downloadable Binaries
JRoppert, For your need, i guess you might want to look at the
Sources
```
```
c:\temp>tidy -help
tidy [option...] [file...] [option...] [file...]
Utility to clean up and pretty print HTML/XHTML/XML
see http://tidy.sourceforge.net/

Options for HTML Tidy for Windows released on 14 February 2006:

File manipulation
-----------------
 -output <file>, -o  write output to the specified <file>
 <file>
 -config <file>      set configuration options from the specified <file>
 -file <file>, -f    write errors to the specified <file>
 <file>
 -modify, -m         modify the original input files

Processing directives
---------------------
 -indent, -i         indent element content
 -wrap <column>, -w  wrap text at the specified <column>. 0 is assumed if
 <column>            <column> is missing. When this option is omitted, the
                     default of the configuration option "wrap" applies.
 -upper, -u          force tags to upper case
 -clean, -c          replace FONT, NOBR and CENTER tags by CSS
 -bare, -b           strip out smart quotes and em dashes, etc.
 -numeric, -n        output numeric rather than named entities
 -errors, -e         only show errors
 -quiet, -q          suppress nonessential output
 -omit               omit optional end tags
 -xml                specify the input is well formed XML
 -asxml, -asxhtml    convert HTML to well formed XHTML
 -ashtml             force XHTML to well formed HTML
 -access <level>     do additional accessibility checks (<level> = 0, 1, 2, 3).
                     0 is assumed if <level> is missing.

Character encodings
-------------------
 -raw                output values above 127 without conversion to entities
 -ascii              use ISO-8859-1 for input, US-ASCII for output
 -latin0             use ISO-8859-15 for input, US-ASCII for output
 -latin1             use ISO-8859-1 for both input and output
 -iso2022            use ISO-2022 for both input and output
 -utf8               use UTF-8 for both input and output
 -mac                use MacRoman for input, US-ASCII for output
 -win1252            use Windows-1252 for input, US-ASCII for output
 -ibm858             use IBM-858 (CP850+Euro) for input, US-ASCII for output
 -utf16le            use UTF-16LE for both input and output
 -utf16be            use UTF-16BE for both input and output
 -utf16              use UTF-16 for both input and output
 -big5               use Big5 for both input and output
 -shiftjis           use Shift_JIS for both input and output
 -language <lang>    set the two-letter language code <lang> (for future use)

Miscellaneous
-------------
 -version, -v        show the version of Tidy
 -help, -h, -?       list the command line options
 -xml-help           list the command line options in XML format
 -help-config        list all configuration options
 -xml-config         list all configuration options in XML format
 -show-config        list the current configuration settings

Use --blah blarg for any configuration option "blah" with argument "blarg"

Input/Output default to stdin/stdout respectively
Single letter options apart from -f may be combined
as in:  tidy -f errs.txt -imu foo.html
For further info on HTML see http://www.w3.org/MarkUp
```
```