Doctype Checker
Checks that the HTML starts with a doctype.
Reading the result
Without one, browsers fall into quirks mode.
Limitations
Reads one page as raw HTML, so anything added by JavaScript is not seen.
Example
Enter example.co.uk and run the check. The report opens when the check finishes.
Questions
What does the Doctype Checker do?
Checks that the HTML starts with a doctype.
How should I read the result?
Without one, browsers fall into quirks mode.
What can it not tell me?
Reads one page as raw HTML, so anything added by JavaScript is not seen.