Documentation of the Programmatic Interface (API) to The W3C Markup Validation ServiceMarkup Validator Web Service API For programmatic checking of modern HTML documents, use the API provided by the W3C HTML Checker. To do that, call https://validator.w3.org/nu/ or the URL for another instance of the W3C HTML Checker, and consult the following documentation: W3C HTML Checker GET interface W3C HTML Checker POST interface W3C HTML Checker parameters W3C HTML Checker out=json format W
