Your data is never sent to a server or stored anywhere. All processing happens in your browser.

URL Encode / Decode — Percent Encoding, In-Browser

Mode
Output

How to Use

Type or paste text into the input area to instantly URL-encode or decode it. Use the toggle to switch between Encode and Decode mode. Click the Copy button to copy the output to your clipboard.

What Is URL Encoding

URL encoding (also known as percent-encoding) converts characters that are not allowed in URLs into a %XX format. Spaces become %20, and non-ASCII characters such as Japanese or emoji are encoded as their UTF-8 byte sequences. It is widely used in web form submissions, API requests, and building query string parameters.

Use Cases

  • Building query strings — correctly construct URLs with parameter values containing special or non-ASCII characters
  • Encoding form data — prepare POST request data in application/x-www-form-urlencoded format
  • API parameter handling — safely encode parameters passed to REST API endpoints
  • Deep linking with special characters — properly encode URL schemes containing special or multibyte characters

Reserved URL Characters

RFC 3986 defines reserved characters that have structural meaning in URLs. The characters : / ? # [ ] @ serve as delimiters between URL components, while ! $ & ' ( ) * + , ; = function as sub-delimiters. When these characters appear as data rather than structure, they must be percent-encoded. For example, to include "C++ & Java" in a search query, + must become %2B and & must become %26, otherwise the URL will be misinterpreted.

encodeURI vs encodeURIComponent

JavaScript provides two encoding functions. encodeURI() encodes an entire URL and preserves structural characters (: / ? # etc.). encodeURIComponent() encodes a single parameter value and encodes nearly all non-alphanumeric characters, including reserved ones. The rule of thumb: use encodeURIComponent() for query parameter values, and encodeURI() for complete URLs.

Privacy

All encoding and decoding happens entirely in your browser. Your data is never sent to a server, stored, or logged. You can safely process sensitive content such as API keys, tokens, or personal information.

FAQ

Does this tool use encodeURI or encodeURIComponent?

It behaves like encodeURIComponent, encoding reserved characters such as : / ? # & = as well. That makes it ideal for encoding query parameter values. Keep in mind that running an entire URL through it will also encode its structural characters.

Is it safe to paste text containing API keys or tokens?

Yes. Both encoding and decoding run entirely in your browser, and your input is never sent to a server, stored, or logged. You can safely convert sensitive strings.

Can it correctly encode Japanese characters and emoji?

Yes. Multibyte characters and emoji are converted to their UTF-8 byte sequences, with each byte output in %XX form. For example, "あ" becomes %E3%81%82.

Is there a limit on how many characters I can convert?

There is no fixed character limit in the tool. Because everything is processed in browser memory, extremely large inputs may slow down depending on your device's performance.

What happens if a percent sequence is malformed during decoding?

Invalid sequences like %ZZ, or byte sequences that aren't valid UTF-8, cause decoding to fail and are reported as an error. Check the original string for missing or corrupted encoding.