HTML Entity Encoder

HTML entity encoding converts special characters into their HTML entity representations — sequences that browsers interpret as specific characters rather than HTML syntax. The most critical characters to encode are: less-than (<) becomes &lt;, greater-than (>) becomes &gt;, ampersand (&) becomes &amp;, double quote (") becomes &quot;, and single quote (') becomes &#39; or &apos;. Without encoding, these characters would be interpreted as HTML markup, potentially breaking the page structure or enabling cross-site scripting (XSS) attacks. Beyond the security-critical characters, HTML entities represent characters that don't exist on standard keyboards: non-breaking spaces (&nbsp;), em dashes (&mdash;), copyright symbols (&copy;), mathematical operators, arrows, and the full range of Unicode characters using numeric references (&#8212; for em dash, &#x2014; in hex). Named entities (&euro;, &pound;, &yen;) provide readable references for common symbols. The AllTools HTML Entity Encoder handles both encoding (converting characters to entities) and decoding (converting entities back to characters) in the browser. Your content stays on your device — important when encoding user-generated content, template literals, or database values that may contain sensitive information.

HTML entity encoding is one of the primary defenses against cross-site scripting (XSS) attacks — one of the most prevalent web security vulnerabilities. XSS occurs when an attacker injects malicious HTML or JavaScript into a web page, typically through user input that is displayed without proper encoding. If a comment field accepts <script>stealCookies()</script> and displays it without encoding, the script executes in every visitor's browser. Encoding converts the angle brackets to &lt;script&gt;, displaying the text harmlessly without execution. Modern web frameworks (React, Vue, Angular, Django, Rails) automatically encode output by default, but developers must understand encoding to recognize contexts where automatic protection doesn't apply: innerHTML assignments, dangerouslySetInnerHTML in React, href attributes that accept javascript: URLs, and template literals injected into script contexts. The AllTools encoder helps developers test encoding behavior, verify that their application's output encoding works correctly, and encode content for contexts where manual encoding is required — email HTML templates, static HTML files, and CMS content management.