The source code for the W3C Markup Validation Service is available under the terms of the W3C Software License. Source tarball of the latest production version is always available at <http://validator.w3.org/validator.tar.gz>. Development code is only available from CVS.
If you just want to glance at the code, or see its revision history, you can browse it on the web.
The most interesting files are currently a CGI script called "check" that does pretty much everything, and possibly also the httpd.conf configuration file snippet for Apache. Select the topmost revision numbers on these pages to see the most recent revision of each file.
If you just want to glance at the code, or see its revision history, you can browse it on the web.
The most interesting files are currently a CGI script called "check" that does pretty much everything, and possibly also the httpd.conf configuration file snippet for Apache. Select the topmost revision numbers on these pages to see the most recent revision of each file.
If you want a copy of all the files that make up the service, you can download a tarball of the code (~300kB) and the DTDs (~500kB).
Fedora/Red Hat RPM packages of the validator are available, courtesy of Ville Skyttä, at Fedora Project, <http://fedoraproject.org/>. The name of the validator package is w3c-markup-validator, use the standard automated package management tools of the distribution (such as yum) to install it along with its dependencies.
In addition to different Fedora versions, the RPMs should be adaptable to other RPM based systems.
openSUSE/SUSE Linux RPM packages are available, courtesy of Sierk Bornemann, at sierkbornemann.de, <http://sierkbornemann.de/pub/tools/w3c-markup-validator/>. Additionally, you can also get these packages from the new software repository of the openSUSE build service at <http://software.opensuse.org/download/validators/> or one of its mirrors.
The RPM packages, maintained by Sierk Bornemann, are optimized for use in a local network (running in a VirtualHost is recommended) for home office or web agency use.
Note that the Validator RPMs have several dependencies, you'll have to satisfy them. You can get these RPMs from openSUSE (other dependencies are included in the openSUSE distribution) or partly from sierkbornemann.de.
In addition, each of these may have further dependencies that must be satisfied. All the necessary RPMs are either included in the openSUSE distribution or are additionally available at sierkbornemann.de or at <http://software.opensuse.org/download/validators/> or one of its mirrors. Use of an automated package management tool to install the packages, such as YaST, rug, y2pmsh, smart, apt4rpm or yum is recommended. See the openSUSE documentation for information about configuring these tools.
A Debian package is available, courtesy of Frédéric Schütz.
Starting with Debian 3.1 ("Sarge"), the package and all its dependencies are included in the official Debian distribution, and can be installed by running the command apt-get install w3c-markup-validator as root.
Debian 4.0 ("Etch") includes version 0.7.4 of the validator; the Debian Testing and Unstable distributions usually include the latest version.
If you intend to actively mirror the code and/or contribute patches to the code, you should install and become familiar with CVS; this is the tool we use for revision control and is generally a good thing to get to know.
For instructions on how to retrieve the code using CVS, see our web-based interface to the repository.
The purpose of making the source code available is partly to allow others to set up mirrors of the service (either publicly or within an intranet behind a firewall), but also to allow us to collaborate on making the service better! If you are interested in helping with the development, we suggest you first install the code and read our instructions for developers.