URL Encoder / Decoder

Encode and decode URLs and URL components with percent-encoding. 100% client-side.

Decoded

Using encodeURIComponent()

Encoded

Special Character Reference ▸

Character	Encoded	Description
	%20	Space
!	%21	Exclamation
#	%23	Hash
$	%24	Dollar
&	%26	Ampersand
'	%27	Single quote
(	%28	Open paren
)	%29	Close paren
+	%2B	Plus
,	%2C	Comma
/	%2F	Slash
:	%3A	Colon
=	%3D	Equals
?	%3F	Question mark
@	%40	At sign

About This Tool

## Understanding URL Encoding

URL encoding, formally known as percent-encoding, is defined in RFC 3986. It ensures that URLs contain only valid ASCII characters by replacing unsafe characters with a % followed by their hexadecimal value.

### Reserved vs. Unreserved Characters

**Unreserved characters** (never encoded): A-Z, a-z, 0-9, - _ . ~

**Reserved characters** (encoded when used outside their special meaning): : / ? # [ ] @ ! $ & ' ( ) * + , ; =

### When to Use Each Function

Use `encodeURIComponent()` when encoding a value that will be placed in a query parameter, path segment, or fragment. Use `encodeURI()` only when encoding a complete URL string where you want to preserve the URL structure characters.

### Security Considerations

Always encode user-supplied data before inserting it into URLs to prevent URL injection and open redirect vulnerabilities. Double-encoding (encoding an already-encoded string) is a common mistake that leads to broken links.

Frequently Asked Questions

What is URL encoding?

URL encoding (percent-encoding) replaces unsafe or reserved characters in a URL with a percent sign (%) followed by two hexadecimal digits representing the character's ASCII value. For example, a space becomes %20.

What is the difference between encodeURI and encodeURIComponent?

encodeURI() encodes a complete URL and preserves characters with special meaning (://?#&=). encodeURIComponent() encodes a single URL component (like a query parameter value) and encodes ALL special characters including those preserved by encodeURI.

When should I URL-encode data?

URL-encode data when building query parameters, form submissions, or any time user input is included in a URL. This prevents injection attacks and ensures special characters don't break the URL structure.

Why is + used for spaces in some URLs?

The + character for spaces comes from the application/x-www-form-urlencoded format used in HTML forms. In standard URL encoding (RFC 3986), spaces should be encoded as %20. Both are widely accepted by web servers.