# Validation Tools — HTML Fundamentals: Structure, Forms and Accessibility

Source: https://www.skillbyai.com/en/html/html-validation-tools

> Catch markup errors early with the W3C validator and editor checks before you publish.

## The W3C validator

`validator.w3.org` checks a page's HTML against the official spec and flags unclosed tags, invalid nesting, and more.

## Lint as you type

Editors like VS Code flag many HTML mistakes live — catching a typo before you even save is faster than validating later.