Website validators like the W3C Markup Validation Service check a web page for validation errors. Webmasters use these services to correct validation errors on their websites.

Here is an example why validation is important. About a year ago I noticed that the RSS feed of Ghacks was throwing an XML error in Internet Explorer 8. This was caused by a single character in one of the latest articles that was not escaped (meaning instead of writing the character & directly one would have to use & instead.

That single character caused problems in the feed delivery, and I had to work longer than usual to get it fixed. Consequences of invalid code are not always that drastic, but it exemplifies the impact that it can have on a website.

Validome is another website validation service. It is a bit stricter when it comes to validating pages. It can happen that a page passes as a XHTML 1.0 Transitional document in the W3C validation, and fails in the Validome validation.

Another difference between the two validation engines is that Validome supports verifications of local and remote documents. Users can either enter an url in the form on the site, or upload a document from their local computer system.

Extended settings are offered to check the document with a specific user agent or language.

A click on Validate performs the validation of the document. Errors are displayed directly.

The service lists the line and column of the validation error, the error position and an explanation of the error. This is often enough to fix the issue in the document.

Validome is an excellent alternative to the W3C validation service. It is usually enough to use Validome since it appears to be stricter in the validation. Most webmasters on the other hand will probably use both services anyway.

The relevant characters that need to be escaped are ', ", &, < and >. (I had to escape them while writing this article to avoid xml errors on the page. Webmasters have several options to escape these characters. They can escape them manually, use an online tool to convert them (see How To Display Valid Markup Code In Websites) or a software program like the XML Escape Tool.

Source code has to be pasted into the first form field in the application window. The tool can then escape the source code if the user clicks on the Escape button or unescape the source if the Unescape button is pressed.

The resulting code can be copied automatically to the Windows clipboard. The benefit of using a desktop software program to escape the characters is that it works if no Internet connection is available. Users who want to try the software can download it from the developer’s website.

Sticking to standards can therefore lead to issues with certain web browsers, which lack support for the latest tags or render pages wrong.

The W3C therefore has its own web browser and editor which adheres to standards more than many browsers and supports certain new technologies others don’t, such as RDF annotation. This browser is Amaya, an open-source and cross-platform browser.

Amaya can handle a wide-range of open file formats, including HTML, CSS, XHTML, SVG and MathML.

The software integrates the browser and web editor: when you go to a web page, it can be edited inside the browser. It also instantly displays syntactic errors.

It also integrates the mark-up languages. For example, in a web page, one can write formula utilising MathML or add SVG shapes inside the software.

Amaya is a reasonable WYSIWYG editor and a good web browser for developmental purposes. It is also good to produce rich web-pages, which include other pieces of mark-up than HTML.

Update: Amaya has not been updated in the last two years. While it is still possible to use the cross-platform HTML editor it needs to be noted that it does not support recent technology advancements. This includes no support for HTML5 or CSS3 in the last release.

Windows and Linux users find in Blue Griffon a suitable alternative. Blue Griffon user however need to know HTML to work with the program, as it does not display information about elements that can be selected in the editor. Users who know their HTML elements will find it to be a suitable alternative for Amaya.

The document viewer only supports the new docx file format at this point but as this is the most commonly encountered format it should suffice for the moment. The web browser add-on is available for both the Windows and Linux operating system and supplied as a xpi file which can be loaded and installed easily. Another version for the command line of both operating systems is provided as well.

The web browser plugin works by simply dragging and dropping docx documents into a Firefox tab or window. The add-on will automatically process the document and display it in the web browser. There is currently no direct way to open docx files that are linked from websites but it is possible to associate the Firefox web browser with the docx format in the operating system to either open the documents automatically or on right-click and selection with it.

The next installment of the Open XML Document Viewer is slated for a April 2009 release which will add support for the Opera and Internet Explorer web browser, server side support, document themes and drawing shapes.