HTML Entity Encoder / Decoder

HTML Entity Encoder / Decoder converts between plain text and HTML entity notation instantly. Paste text into the INPUT panel and the encoded output appears in the OUTPUT panel with no delay — no button click, no server round-trip, no data sent anywhere. Developers use it to safely embed user-generated content in HTML templates, to prepare code samples for documentation, and to debug encoded strings from API responses. Email template authors use it to prevent character encoding problems in legacy mail clients. The tool runs entirely in your browser using JavaScript string operations and the browser's native HTML parser.

Encode mode: two scopes

HTML-safe only encodes the five characters that break HTML structure when present in text content: & (ampersand), < (less-than), > (greater-than), " (double quote), and ' (apostrophe). The ampersand is encoded first — before the other four — to prevent double-encoding. If < were encoded first, the & in the resulting < would be re-encoded to < on any subsequent pass. This is the correct scope for the vast majority of use cases: CMS rich-text fields, email template body content, API response values that will be rendered inside HTML, and code snippets embedded in documentation.

All non-ASCII encodes the same five HTML-structural characters first, then additionally converts every character with a Unicode code point above U+007E (tilde, decimal 126) to a numeric HTML entity (&#N; where N is the decimal code point). Use this scope when the target environment requires strict 7-bit ASCII output. Legacy email transport systems using older SMTP servers, some older CMS fields, and certain HTTP header values are examples where non-ASCII bytes can be stripped, corrupted, or misinterpreted by intermediate systems that do not declare UTF-8 handling correctly.

Decode mode: what it handles

The decoder uses the browser's own HTML parser via the textarea technique: the encoded string is assigned to a hidden textarea element's value property and read back as .value text. This handles all three entity notations correctly and safely. Named entities like &,  , ©, €, and — decode to the correct characters. Numeric decimal entities like   (non-breaking space) and — (em dash) decode correctly. Numeric hexadecimal entities like © (copyright symbol) also decode. No innerHTML assignment is used anywhere in the decode path, so there is no risk of script execution when decoding content that contains <script> tags as entities — the parser never sees them as markup.

Apostrophe encoding: ' not '

The encoder outputs ' for apostrophes rather than the named entity '. This is intentional. ' is defined in XML and XHTML but was not part of the HTML 4.01 specification. Some older HTML parsers and browsers do not recognize it. The numeric form ' works in every HTML context without exception, including old Internet Explorer versions, legacy email clients, and XML parsers that also accept HTML.

Input size limit

The tool accepts up to 100 KB of input text. For larger documents, split the content into sections and encode each separately. All conversion runs synchronously in JavaScript — there is no background processing or queue, so results appear the moment you stop typing.