URL Encoder / Decoder

What is URL encoding?

URL encoding (also called percent encoding) converts characters that are not allowed or have special meaning in a URL into a safe representation. Each unsafe character is replaced by a percent sign (%) followed by two hexadecimal digits representing the character's UTF-8 byte value. For example, a space becomes %20, an ampersand becomes %26, and an emoji like 🚀 becomes %F0%9F%9A%80.

URLs can only contain a limited set of characters defined by RFC 3986: letters, digits, hyphen, period, underscore, and tilde are "unreserved" and do not need encoding. Characters like / ? # [ ] @ ! $ & ' ( ) * + , ; = are "reserved" and have special meaning in URL structure. Any other character — including spaces, non-ASCII characters, and many punctuation marks — must be encoded.

JavaScript provides two functions: encodeURIComponent() encodes everything except unreserved characters (use for encoding a query string value), and encodeURI() encodes everything except unreserved characters and the reserved characters (use for encoding a complete URL that already has valid structure). This tool supports both modes.

Common mistakes

• Double-encoding — Encoding a string that is already encoded produces double-encoded output (e.g. %2520 instead of %20). Always decode first if you're unsure.
• Using encodeURI for query values — encodeURI() does not encode &, =, and +, which are separators in query strings. Use encodeURIComponent() for individual parameter values.

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