An encoded query value
Input
search%20terms%20%26%20more%3FOutput
search terms & more?About this tool
Decoding converts percent-escapes back into the characters they represent, turning an unreadable URL into something you can actually inspect. It is the fastest way to see what a redirect chain is carrying, or what a tracking parameter actually contains.
Malformed input is common (truncated escapes from a bad copy-paste, or a literal percent sign that was never encoded), so errors here name the specific problem rather than failing silently.
How to use it
- Paste or upload your urlDrop a file onto the input pane, use the file picker, or paste the text directly.
- Adjust the options if neededThe defaults suit most input; open Options to change the behaviour.
- DecodePress Decode, or use Ctrl+Enter (Cmd+Enter on macOS).
- Copy or downloadCopy the result, or download it as a .txt file.
Worked examples
Each example below is executed against this tool by the test suite, so what you see is what the tool actually produces.
UTF-8 escapes
Input
caf%C3%A9%20%F0%9F%8E%89Output
café 🎉Two escapes form the é and four form the emoji.
What to watch for
The details that decide whether a conversion is correct, and where information can be lost without any error being raised.
- Percent-escapes and UTF-8 reassembly
- Each %XX pair becomes one byte, and consecutive bytes are reassembled as UTF-8 text. So %C3%A9 becomes é from two escapes, and a four-escape sequence becomes a single emoji. Decoding is byte-based, which is why an incomplete multi-byte sequence produces an error rather than a partial character.
- Plus signs and form encoding
- In a form-encoded query string a + means a space, but in a URL path it is a literal plus. The default here converts + to a space, which is what you want when inspecting query parameters. Turn it off when decoding a path segment, or a value where + is meaningful, such as a phone number or an email address using plus-addressing.
- Malformed escapes are reported precisely
- A % must be followed by exactly two hexadecimal digits. Input like %ZZ or a trailing % is invalid, and the error points at the offending sequence. The usual causes are a truncated copy, or an unencoded literal percent sign that should have been written as %25.
- Double-encoded values need decoding twice
- If the result still contains visible escape sequences, the value was encoded more than once, %2520 decodes to %20, which then decodes to a space. Run the tool again on its own output until the text stops changing.
Limitations
- Cannot tell a form-encoded query from a URL path, so the + handling is a choice you make.
- Double-encoded input requires running the tool more than once.
- Processing happens in your browser, so very large inputs are bounded by available memory. Files above roughly 10 MB are handled but will feel slower, and multi-hundred-megabyte files are better suited to a command-line tool.
Questions
- Why did my plus sign become a space?
- Because form-encoded query strings use + for a space, and that is the default. Turn off "Treat + as space" when the plus is literal, as in a path segment or a plus-addressed email.
- Why do I still see %20 in the output?
- The value was double-encoded: the original % was itself encoded as %25. Decode the output a second time.
- What causes "malformed escape sequence"?
- A % not followed by two hex digits, usually a truncated paste, or a literal percent sign that should have been %25.