In a nutshell: this page lists HTML validators (which check HTML code for
standards compliance and errors), CSS validators (which check Cascading Style
Sheets for errors and standards compliance), browser compatibility checkers
(checks your page to see if it is compatible with various browsers), broken link
(or dead links) checkers, accessibility checking (check if your web page is
accessible to people with disabilities), etc.
Free HTML Validators, XHTML Validators, Browser Compatibility Checkers
You can use the W3 Consortium's HTML validator to check your web
documents either by giving it your web page's URL or uploading your document
directly to the validator. Many people consider it the authoritative source
for checking your web pages for standards compliance (since the W3
Consortium is responsible for the various HTML/CSS standards). Source code
for the validator is also available.
HTML Tidy is not just a HTML validator for your web documents. It is able
to correct (repair and fix) bad HTML code and give you pointers to areas
where you need to change in order to make your web page accessible to people
with disabilities. Source code and binaries are available for a wide variety
of operating systems, including Windows 95/98/NT/2000, Mac OS, Atari, Amiga,
BeOS, AIX, Linux, UnixWare, HP-UX, MSDOS, Solaris, OS/2, FreeBSD, RISC OS,
MiNT (Atari) OS, etc. There is even a Java port of HTML Tidy.
The Web Page Purifier allows you to check your HTML pages for compliance
("purity") with various HTML standards (eg HTML 4.0 Transitional,
HTML 4.0 Strict, WebTV 1.1, HTML 3.2, etc). There's a form where you can
enter the URL of the page to check, or you can also download the Perl CGI
If you need to check your web pages to see if they are compatible with
browsers that lack certain features, this page checker might be useful. You
actually have to specify which features you do not want on a page, like
tables, images, etc. It is probably not as useful as the title of the site
sounds, since if you knew which features you needed to avoid, you would not
put them in a page in the first place. (It would be better if there were
simple options where you could simply select the browser versions you want
to check compatibility with, instead of having to specify features.)
A-Prompt is a Windows program that checks your pages for accessibility
issues and fixes the pages for you (with your help). It has a Wizard-like
interface which guides you through the individual (potential) problems that
your web page may have and prompts you for information for repairing the
Bobby checks your HTML pages for areas that might pose difficulties for
people with disabilities. You simply enter the URL of your web page and it
will give you a report after it visits that URL. You can also download Bobby
to use on your machine (it's a Java application). It can check your site
against the US Section 508 Guidelines, or against the Web Content
Accessibility Guidelines 1.0.
This is the W3 Consortium's CSS validator for validating Cascading Style
Sheets. You can either download it and use it on your own machine, upload
your cascading style sheet (CSS) to their online service, or supply your URL
for their spider to visit your site. The W3 Consortium is responsible for
the various CSS and HTML standards.
Worried about broken links in your web documents? This online validator
from the W3 Consortium is able to recursively check your document for dead
links. You simply enter a URL in the form provided, and it will visit your
site and check the links.
Xenu is a utility for Windows that checks your web site for broken links.
It can work both with a "live" website as well as on a copy of
your web site residing on your own hard disk. It's a favourite of many
webmasters for checking broken links on their site.