UITest.com Site Check - Tool tests websites with a wide range of usability, accessibility, web standards and best practices checkers. Backward Compatibility Viewer - Web page viewer for checking backward compatibility according to HTML version standards or specific features. Cache Manifest Validator - Online tool to validate web application offline storage manifests. intoDNS - Checks the health and configuration of DNS and mail servers. Ubiqway Website Checker - This service tests if a web page follows good practices related to performance, usability, web standards, and search engine friendliness. Favicon Checker - Check the Favicon of a website and validate it works well on all major platforms. Internationalization Checker - W3C tool to determine the level of internationalization-friendliness of a web page. Server Response Checker - Tool to read server response headers in different formats. Twitter Card Validator - Tool to validate HTML for Twitter Cards. Requires a Twitter account. Microsoft Static Code Scan - Tool to scan code on any URL for out-of-date libraries, layout issues, and accessibility concerns. Facebook Sharing Debugger - Facebook crawler to see the information that is used when website content is shared on Facebook products. Login required. Mozilla Observatory - Tool to help developers, system administrators, and security professionals configure their websites safely and securely. Accelerated Mobile Pages Project Test - Google tool to test if an AMP page is valid. SSL Server Test - Tool performs an analysis of the configuration of SSL web servers on the public Internet. CSS Stats - Tool to view statistics about CSS files. Contains amounts of rules, selectors, declarations, and properties.