Global statistics
You can learn from the statistics about the dominating browser, the most popular operating system, and mostly used resolution.
Html-code validator
The service checks documents like HTML and XHTML for conformance to W3C Recommendations and other standards.
Search Engine Position Analyzer Service is useful for tracking positions of your web site in mostly known search engines by defined keyword.
WHOIS service Domain based services allow you to see the following information: date of registration, name of registrar and much more.
BrowserCheck This service allows you to check how's your site look in different browsers (Internet explorer, opera, firefox).
Search engine spider simulator This service helps you find out for yourself how a search engine reacts to your pages. The search engine spider simulator provides you with a report on aspects of the page that are used to determine how highly in a search engine the page is ranked, and also gives some general usability feedback.
WhatTheFont You upload a picture with a graphic label, the service determines what font is using there.