Total Validator - Total Validator can check your website to help ensure that it is accessible, uses valid HTML and CSS, has no broken links, and is free from spelling mistakes.
Bots UI Kit - Fully customizable Sketch UI Kit for Messenger Platform
W3C Markup Validation Service - Validates HTML markup of web pages, one at a time.
Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
Rocket Validator - Site-wide Accessibility and HTML validation made easy. With a single click, Rocket Validator will check thousands of web pages on your site for Accessibility and HTML conformance, producing a detailed, actionable report on seconds.
Infinity Dashboard - A beautiful way to keep track of anything you want 📊