HTML encoding replaces characters that have structural meaning in markup with named or numeric entities: < becomes <, > becomes >, & becomes &, and quotes become " and '. Escaping these five characters is the baseline defence against cross-site scripting, because it stops user-supplied text from being parsed as a tag or attribute. It is also how you display code samples on a page without the browser executing them. This encoder handles the core five plus optional entity encoding for non-ASCII characters, which is useful for legacy systems or email templates that do not declare UTF-8 reliably.
Free, fast, and runs entirely in your browser — no signup, no upload to a server.