The pages below allow you to see different types of mixed content and test how they behave in your browser. The "Secure" pages are referencing assets with HTTPS, the "Non-Secure" pages are referencing them with HTTP. Generally, you'll observe the same behavior with both Secure pages and the Secure HTTP page for a given test; the behavior will change on the Non-Secure HTTPS page.
For more information, or to find mixed content pages on your site, visit Missing Padlock.
Examples of various types of bad certificates are available at: badssl.com.