Base64, URL, HTML entity and hex encoder and decoder

No. Every codec is plain JavaScript running in your browser, and the page makes no network request with your text. Copy puts the result on your clipboard only when you press the button, and Download saves a file on your own device. Once the page has loaded it works offline.

The text is turned into UTF-8 bytes first and those bytes are encoded, which is what every modern system expects. नमस्ते is 6 characters but 18 bytes, so its Base64 is 24 characters: 4KSo4KSu4KS44KWN4KSk4KWH. A single 😀 is 4 bytes and becomes 8J+YgA==. The Hex codec shows the same bytes as digits, two per byte. Decoding goes the other way, and if the bytes turn out not to be UTF-8 text, as with an image or a signature, it says so and shows them as hex.

Standard Base64 uses + and /, which have meanings of their own in URLs and file names. The URL-safe alphabet from RFC 4648 section 5 swaps them for - and _. The = padding only brings the length up to a multiple of 4; JSON Web Tokens and most URL-safe uses leave it off, which is what Drop the = padding does. The decoder accepts either alphabet, with or without padding, and ignores spaces and line breaks, so a wrapped or pasted value decodes as it is.

A value (encodeURIComponent) escapes everything except letters, digits and - _ . ! ~ * ' ( ), so Tom & Jerry becomes Tom%20%26%20Jerry and can sit safely inside a query string. A whole URL (encodeURI) also leaves ; , / ? : @ & = + $ # alone because they give the URL its structure, so https://example.com/?q=Tom & Jerry becomes https://example.com/?q=Tom%20&%20Jerry, which a server reads as two parameters. Encode each value first, then build the URL. A space is always %20 here; the + that form submissions use for a space is left as it is when decoding.

Encoding always covers the five characters that break HTML, & < > " and ', written as & < > " and ' (HTML 4 does not define '). With Also encode non-ASCII characters on, every character above ASCII is encoded too: as a named entity where the HTML standard defines one, such as é or →, and as a number otherwise. Decoding knows every named reference in the HTML standard, all 2,125 of them, plus decimal and hex numbers, the legacy names browsers accept without a semicolon such as &copy, and the browser quirk that reads – as an en dash. An unknown name is left as it is.