tinymce-docs/_includes/configuration/linkchecker_service_url.md

linkchecker_service_url

A URL of the server-side link validation service. This is required option, without it plugin will fail to operate and will throw a corresponding warning on the screen.

Type: String

Example: Using linkchecker_service_url

tinymce.init({
    selector: 'textarea',
    plugins: 'linkchecker',
    linkchecker_service_url: 'http://mydomain.com/linkchecker'
});