URL encoder and decoder

How to use the URL encoder and decoder

1. Pick Encode or Decode.
2. Pick a mode. Component is right most of the time: it encodes one value that goes into a URL, such as a search term. Whole URL fixes spaces and accents in a URL that is already put together. Form writes spaces as +, as HTML forms do. RFC 3986 strict also encodes ! ' ( ) and *.
3. Type or paste your text. The result updates as you type; Copy output copies it. The panel shows the same call in JavaScript and Python.
4. To take a URL apart, paste it into Parse a URL. You get the scheme, host, port, path, each query parameter decoded, and the fragment.

A decoding error, such as a % that is not followed by two hex digits, is explained in words with its position. Everything runs in this page: your entries are not saved or sent.

What percent encoding is

RFC 3986, the standard for URIs, splits characters into two groups. Unreserved characters are always safe: unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~". Reserved characters have jobs in a URL: the general delimiters : / ? # [ ] @ and the sub-delimiters ! $ & ' ( ) * + , ; =. When a reserved character is meant as plain data, or a character is not allowed at all (a space, an accent, an emoji), it is percent-encoded.

A percent-encoded byte is a % followed by two hex digits. Text is first turned into UTF-8 bytes, so é (bytes C3 A9) becomes %C3%A9 and 😀 (F0 9F 98 80) becomes %F0%9F%98%80. RFC 3986 says producers "should use uppercase hexadecimal digits for all percent-encodings", which this tool does. The % sign itself "must be percent-encoded as "%25"" when it is data.

URL encoding table: space, forward slash, ampersand and more

URL encode forward slash: in a query value or a single path segment, write / as %2F (Component mode). Whole URL mode keeps it, because there it separates the path. URL encode ampersand: & separates query parameters, so an ampersand inside a value must be %26: the search term Tom & Jerry is q=Tom%20%26%20Jerry, or q=Tom+%26+Jerry as form data.

URL encode space: %20 or +?

Both appear, and which one is right depends on where the text goes. In a path, and in RFC 3986 percent-encoding generally, a space is %20. The + for a space comes from HTML forms. The WHATWG URL Standard, which browsers follow, defines the application/x-www-form-urlencoded format (it calls it "in many ways an aberrant monstrosity", a result of history), and when serializing it says: "If spaceAsPlus is true and byte is 0x20 (SP), then append U+002B (+)". Its parser does the reverse: "Replace any 0x2B (+) in name and value with 0x20 (SP)."

So in a query string built by a form or by URLSearchParams, a + means a space, and a real plus sign must be %2B. In a path, + is just a plus. That is why this decoder turns + into a space only in Form mode. When in doubt, %20 is read as a space everywhere.

URL encode in JavaScript: encodeURIComponent vs encodeURI

MDN says encodeURIComponent() escapes all characters except A-Z a-z 0-9 - _ . ! ~ * ' ( ). encodeURI() also leaves ; / ? : @ & = + $ , #, the characters that "may be part of the URI syntax". MDN's advice: encodeURI "is used to encode a URL as a whole, assuming it is already well-formed", and to build a URL from values, use encodeURIComponent on each value.

Using encodeURI on a value is a common bug: the & in café & cake would split the parameter in two. For RFC 3986 strictness, MDN shows encodeURIComponent followed by replacing !'()*, because "The more recent RFC3986 reserves !, ', (, ), and *"; that is this tool's RFC 3986 strict mode. Both functions throw URIError on a lone surrogate (half of an emoji); this page names its position instead.

URL encode in Python: quote and quote_plus

Python's urllib.parse.quote never encodes "Letters, digits, and the characters '_.-~'", and by default it is "intended for quoting the path section of a URL", so its safe parameter defaults to '/'. quote_plus is "Like quote(), but also replace spaces with plus signs, as required for quoting HTML form values".

The first and last results are the examples in the Python documentation. To decode, use unquote, or unquote_plus for form data.

URL decode: errors and double encoding

Decoding turns each %XX back into a byte, then reads the bytes as UTF-8. Two things can go wrong, and the decoder tells you where:

• A % that is not followed by two hex digits, such as 50%off. The literal percent sign should have been written %25.
• Bytes that are not UTF-8, such as %E9t%E9. That is é in the old Latin-1 or Windows-1252 encoding; in UTF-8, é is %C3%A9.

If decoding once still leaves %20 or %2F in the text, it was encoded twice (the % became %25). Decode again. The encoder warns you when the text you are about to encode already contains escapes.

Parse a URL into its parts

RFC 3986 names the parts with this example: foo://example.com:8042/over/there?name=ferret#nose has the scheme foo, the authority example.com:8042, the path /over/there, the query name=ferret and the fragment nose. The parser on this page uses the browser's own URL API, so it splits a URL exactly as browsers do. Query parameters are decoded the form way (+ is a space), and an international domain name is shown in its xn-- form, which is what is sent over the network. If your parameters hold JSON, paste the value into the JSON formatter; if one looks like eyJ..., it is probably a token for the JWT decoder. URL encoding is not Base64: to carry binary data as text, use the Base64 encoder.

Questions and answers

Sources

Checked on 13 October 2026. If a rule has changed, please tell us.

• RFC 3986: Uniform Resource Identifier (URI): Generic Syntax (IETF, January 2005)
• URL Standard (WHATWG): application/x-www-form-urlencoded and percent-encode sets
• encodeURIComponent() (MDN Web Docs)
• encodeURI() (MDN Web Docs)
• urllib.parse: Parse URLs into components (Python documentation)