The pages linked to below were generated using Java CharsetEncoders. Each page uses JavaScript to compare the characters as the browser decodes them with the codes used when encoding the page. If they all match, you should see 'PASSED!' in the browser window. If some do not match, you should see 'FAILED!' followed by a list of up to 16 character codes found different. If more than 16 characters were found different, the remaining ones will be counted but not shown. These pages only test codes points U+0000A0 and up. Lower code points are unlikely to be decoded badly, and a few of them could corrupt the html code.
If you want to suggest other character sets, etc., you can email me: mauvecloud at mauvecloud dot net (mailto link avoided to discourage spam generators) Other charsets (not included in Java Standard API):