What URL encoding does
URLs can only contain a limited set of characters. Anything else, such as spaces, accented letters, emoji, or characters with a special meaning like & and ?, must be percent-encoded: converted to UTF-8 bytes and written as % followed by two hexadecimal digits. For example, a space becomes %20 and é becomes %C3%A9.
A value or a complete URL?
This choice matters, and picking the wrong one is a common source of broken links.
| Mode | Use it for | Leaves unchanged |
|---|---|---|
A value or part of a URLencodeURIComponent | A single query parameter value, path segment or fragment, before you insert it into a URL. | A–Z a–z 0–9 - _ . ! ~ * ' ( ) |
A complete URLencodeURI | A whole URL that already has the right structure but contains spaces or non-ASCII characters. | The above, plus URL syntax: ; , / ? : @ & = + $ # |
For example, to put rock & roll in a search link, encode it as a value:rock%20%26%20roll. Encoding it as a complete URL would leave the & alone, and the server would read it as the start of a new parameter.
How to use it
- Choose whether your input is a single value or a complete URL.
- Paste your text and press Encode or Decode. After that, the result updates as you type.
- Use Use as input to run the result through again, for example to decode something that was encoded twice.
Limitations
- Encoding always produces UTF-8, the standard for URLs. Text that was encoded with a legacy character set (such as Latin-1, where
éis%E9) cannot be decoded and is reported as an error. - Input is limited to 2 million characters.
Frequently asked questions
Why do spaces sometimes appear as + instead of %20?
HTML forms submitted with the default application/x-www-form-urlencoded format encode spaces as +. Percent-encoding uses %20. Both are common in query strings. When decoding form data, tick Treat + as a space. When encoding, this tool always uses %20, which is valid everywhere.
What does “malformed URI sequence” mean?
It means the text contains a % that is not followed by two hexadecimal digits, or a series of escapes that do not form a valid UTF-8 character. This tool shows you where the problem starts. A literal percent sign must be written as %25.
Is URL encoding the same as encryption?
No. URL encoding only makes text safe to put inside a URL. Anyone can decode it, so never rely on it to hide sensitive information.