What is the difference between encodeURI and encodeURIComponent?

encodeURI encodes a full URL, preserving characters like /, ?, &. encodeURIComponent encodes a URL component (like a query param value), encoding those characters too.

Why are spaces encoded as %20?

URLs cannot contain spaces. Space is encoded as %20 (or + in some contexts). %20 is the standard percent-encoding for a space character.

When should I use + instead of %20 for a space?

Use + only in application/x-www-form-urlencoded data, such as a query string from an HTML form. In a URL path or a generic component you must use %20; a literal + there is interpreted as a plus sign, not a space.

Which characters are reserved in a URL?

RFC 3986 reserves the gen-delims : / ? # [ ] @ and the sub-delims ! $ & ' ( ) * + , ; =. These have special meaning, so encode them as percent values when they appear as literal data rather than as delimiters.

How are non-ASCII characters encoded in a URL?

They are first converted to their UTF-8 byte sequence, then each byte is percent-encoded. For example the character é becomes %C3%A9, which matches what encodeURIComponent() does in JavaScript.

What happens if I encode a URL twice?

Double-encoding turns each % into %25, so %20 becomes %2520. The server then decodes it once back to %20 instead of a space, breaking the value. Only encode a component once, after you have assembled the raw string.

Are path segments and query parameters encoded the same way?

Not exactly. Some characters allowed in a path segment are reserved in a query string and vice versa, so encodeURI() leaves more characters intact than encodeURIComponent(). Use the component variant for individual values you drop into a URL.

URL Encoder / Decoder Online

Char	Encoded	Note
	%20	space
&	%26	ampersand
=	%3D	equals
+	%2B	plus
?	%3F	question mark
#	%23	hash
/	%2F	slash (component)
:	%3A	colon (component)
@	%40	at (component)
%	%25	percent

How to use URL Encoder / Decoder

The URL Encoder / Decoder converts special characters in URLs to and from their percent-encoded equivalents. Spaces, non-ASCII letters, and reserved characters such as &, =, and # must be percent-encoded before being included in a URL query string or path segment. This tool is essential when constructing API calls, debugging HTTP requests and embedding dynamic values in links.

Paste the text or URL you want to encode or decode into the input field.
Choose Encode to convert special characters to %XX sequences.
Choose Decode to convert %XX sequences back to readable characters.
Select the encoding scope: encode full URL (preserves ://) or encode component (encodes everything including :, /, ?).
Copy the result from the output panel.

Your data never leaves your device — 100% private processing.

Percent-encoding rules

Percent-encoding replaces each unsafe byte with a % sign followed by two uppercase hexadecimal digits representing that byte value. RFC 3986 defines unreserved characters (A–Z, a–z, 0–9, -, _, ., ~) which must never be encoded. Reserved characters (: / ? # [ ] @ ! $ & ' ( ) * + , ; =) have special meaning in URLs and must be encoded when used as literal data in a component. A space is encoded as %20 (or + in application/x-www-form-urlencoded form data).

encodeURI vs encodeURIComponent

JavaScript provides two built-in functions for URL encoding. encodeURI is intended for a complete URL and leaves reserved characters (/, ?, #, &, =, :) intact so the URL structure remains valid. encodeURIComponent encodes all characters except unreserved ones, making it safe for encoding individual query parameter names and values. Always use encodeURIComponent for user-supplied data in query strings to prevent injection of additional parameters.

Characters encoded by each function
Character	encodeURI	encodeURIComponent
Space	%20	%20
/	preserved	%2F
?	preserved	%3F
#	preserved	%23
&	preserved	%26
=	preserved	%3D
@	preserved	%40

Worked examples

Encode a query value

Inputs: 'a b&c'

Result: a%20b%26c

Encode a non-ASCII character

Inputs: 'café'

Result: caf%C3%A9

Decode percent-encoding

Inputs: 'https%3A%2F%2Fexample.com%2Fp%3Fx%3D1'

Result: https://example.com/p?x=1

Glossary

Percent-encoding: Replacing unsafe URL characters with a % followed by two hex digits representing the byte value.
Query string: The part of a URL after ? containing key=value pairs separated by & characters.
URI: Uniform Resource Identifier — a string that identifies a resource by location, name, or both.
Reserved characters: Characters with special meaning in URI syntax (/, ?, #, &, =, etc.) that must be encoded when used as literal data.
IDN: Internationalized Domain Name — a domain name containing non-ASCII characters, encoded using Punycode.

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URL Encoder / Decoder

How to use URL Encoder / Decoder

Percent-encoding rules

encodeURI vs encodeURIComponent

Worked examples

Glossary

Related reading

Frequently Asked Questions

Why use URL Encoder / Decoder?

Common use cases

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