What is URL Encoding (Percent Encoding)?
URL encoding, also known as percent encoding, is a mechanism defined in RFC 3986 for representing special characters in a URI. Characters that are not allowed in a URL — such as spaces, ampersands, question marks, and non-ASCII characters — are replaced with a percent sign followed by their two-digit hexadecimal value (for example, a space becomes percent-20). JavaScript provides two built-in functions: encodeURIComponent() encodes all special characters (ideal for query parameter values), while encodeURI() preserves URL-structural characters such as colons, slashes, question marks, and hash signs (ideal for encoding a complete URL without breaking its structure).
How to Use This Free Online URL Encoder & Decoder
- 1Select the mode: 'Encode' to convert text to a URL-safe string, or 'Decode' to convert a percent-encoded string back to plain text.
- 2Choose the encoding function: toggle between encodeURIComponent (encodes everything) and encodeURI (preserves URL structure).
- 3Paste or type your text into the input field. The result updates in real time.
- 4Click the Copy button to copy the output to your clipboard.
Common Use Cases for URL Encoding & Decoding
Building query strings
Safely encode parameter values that contain special characters like &, =, or spaces before appending them to a URL.
Debugging encoded URLs
Decode percent-encoded URLs to read the original values and troubleshoot routing or API issues.
Encoding non-ASCII characters
Convert Unicode characters (Chinese, Arabic, emoji) into percent-encoded sequences for use in URLs that only support ASCII.
Preparing redirect URIs for OAuth
OAuth flows require redirect_uri values to be URL-encoded when passed as query parameters to the authorization endpoint.
Constructing mailto: links
Encode subject lines and body text in mailto: links so special characters render correctly in email clients.
Frequently asked questions
What is the difference between encodeURI and encodeURIComponent?
encodeURI() encodes a full URI but preserves characters that are part of URL syntax (like colons, slashes, question marks, hash, ampersand, and equals). encodeURIComponent() encodes everything except A-Z, a-z, 0-9, and the characters - _ . ~ making it suitable for query parameter values where those structural characters must be escaped.
Why do spaces appear as %20 or + in URLs?
In standard percent encoding (RFC 3986), a space is encoded as %20. In HTML form submissions using application/x-www-form-urlencoded, a space is encoded as +. Both represent a space, but %20 is the universal standard for URLs.
Is URL encoding the same as HTML entity encoding?
No. URL encoding (percent encoding) is for making strings safe inside URLs. HTML entity encoding (for example, using the 'amp' entity for the ampersand character) is for making strings safe inside HTML markup. They serve different purposes and use different syntax.
Is this tool free and private?
Yes. This tool runs entirely in your browser using JavaScript's built-in encoding functions. No data is sent to any server and no sign-up is required.