URL Encoder

URL Encoder/Decoder

Q: What is the difference between URL encoding and HTML entity encoding?

URL encoding replaces unsafe characters with a % followed by a two-digit hexadecimal code and is used to safely embed data in URLs. HTML entity encoding replaces characters like < with < to prevent them from being interpreted as HTML markup.

Q: What is the difference between %20 and + for spaces?

In the path portion of a URL, spaces must be encoded as %20. In the query string, the application/x-www-form-urlencoded format encodes spaces as +. Both are widely understood in query strings, but %20 is the safer, RFC 3986-compliant choice.

Q: When should I URL-encode a value?

URL-encode any data that will be placed in a URL component where that data might contain reserved characters. This applies to query string values, URL fragments, path segments, and usernames or passwords in the authority component.

Q: What is double-encoding and how do I avoid it?

Double-encoding happens when you percent-encode a string that is already percent-encoded, turning %20 into %2520. Avoid it by decoding the string first if it might already be encoded, or by using URL-building APIs that handle encoding transparently.

Encode and decode URLs and query string components. RFC 3986 compliant, supports Unicode/UTF-8, and offers both component and full-URL encoding modes.

Encode & Decode Component vs Full URL RFC 3986 Compliant Unicode / UTF-8 % Encoding Table Copy Output

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Common URL Encoding Reference

The special characters most often encountered in URLs and their percent-encoded equivalents.

Character	Encoded	Context
Space	%20	Spaces in query params (+ is form-specific)
/	%2F	Slash in a query value (not path separator)
:	%3A	Colon in query values or credentials
=	%3D	Equals sign in a query value
&	%26	Ampersand in a query value (else splits params)
?	%3F	Question mark inside a query value
#	%23	Hash inside a URL (else treated as fragment)
+	%2B	Literal plus sign (+ means space in form encoding)
@	%40	At sign in userinfo or query value
%	%25	Literal percent sign (escape the escape character)

Frequently Asked Questions

What is the difference between URL encoding and HTML entity encoding?

URL encoding (percent encoding) replaces unsafe characters with a % followed by a two-digit hexadecimal code, and is used to safely embed data in URLs. HTML entity encoding replaces characters like < with < to prevent them from being interpreted as HTML markup. They solve different problems: URL encoding is for URLs, HTML encoding is for HTML content.

What is the difference between %20 and + for spaces?

In the path portion of a URL, spaces must be encoded as %20. In the query string, the application/x-www-form-urlencoded format (used by HTML forms) encodes spaces as +. Both %20 and + are widely understood in query strings, but %20 is the safer, RFC 3986-compliant choice for non-form data.

When should I URL-encode a value?

You should URL-encode any data that will be placed in a URL component where that data might contain reserved characters. This always applies to query string values, URL fragments, path segments that might contain slashes, and usernames or passwords in the authority component. If you are constructing a URL programmatically, use your language's built-in URL builder to handle encoding automatically.

What is double-encoding and how do I avoid it?

Double-encoding happens when you percent-encode a string that is already percent-encoded, turning %20 into %2520 (because % itself becomes %25). This causes the URL to decode incorrectly. Avoid it by decoding the string first if it might already be encoded, or by using URL-building APIs that handle encoding transparently rather than manually concatenating strings.

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