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

%20 is the standard percent-encoding for a space character. The + sign represents spaces only in application/x-www-form-urlencoded format (HTML form submissions). In path segments and most query parameters, use %20. This tool uses encodeURIComponent(), which produces %20.

Is URL encoding reversible?

Yes, URL encoding is fully reversible. Decoding replaces each percent-encoded sequence with the original character. The toggle in this tool lets you switch between encoding and decoding the same input.

Why does my URL break after encoding?

You likely used component encoding on a full URL, which encodes the ://, /, and ? characters. Switch to Full URL mode (the checkbox in this tool) to preserve the URL structure while encoding only the unsafe characters.

URL Encoder / Decoder

Encode and decode URL strings online. Supports full URL and component encoding.

Full URL mode (preserves :, /, ?, #, etc.)

Input

Output

Why URLs Need Encoding

URLs can only contain a limited set of ASCII characters. Spaces, non-ASCII characters, and reserved symbols like &, =, and # must be percent-encoded to travel safely through HTTP. A space becomes %20, an ampersand becomes %26.

Component vs Full URL Encoding

encodeURIComponent() encodes everything except unreserved characters (A-Z a-z 0-9 - _ . ~). Use it for query parameter values or path segments. encodeURI() leaves structural characters (: / ? # [ ] @) intact. Use it when encoding a complete URL where the structure should remain valid.

Common Encoding Mistakes

Double-encoding happens when you encode an already-encoded string — %20 becomes %2520. This causes broken links and API errors. If your decoded output still contains percent sequences, you likely need to decode again. This tool handles single-pass encoding and decoding. For encoding binary data as text, see the Base64 Encoder / Decoder.

Percent Encoding in Practice

API calls frequently pass user input through query strings. A search query like "cats & dogs" must become cats%20%26%20dogs in the URL. Frontend frameworks handle this automatically for most requests, but manual URL construction (string concatenation in API clients, redirect URLs, OAuth callback parameters) requires explicit encoding. The URL object in JavaScript (new URL()) handles encoding for query parameters when you use the searchParams API. If you're building JSON payloads for those API calls, the JSON Formatter can help you validate the structure.

Unicode and International Characters

Non-ASCII characters (accented letters, CJK characters, emoji) require multi-byte percent encoding. The string "café" encodes to caf%C3%A9 because the UTF-8 representation of "é" is two bytes (0xC3, 0xA9). Internationalized domain names (IDNs) use a separate Punycode encoding system, not percent encoding.

Frequently Asked Questions

What is the difference between %20 and + for spaces?: %20 is the standard percent-encoding for a space character. The + sign represents spaces only in application/x-www-form-urlencoded format (HTML form submissions). In path segments and most query parameters, use %20. This tool uses encodeURIComponent(), which produces %20.
Is URL encoding reversible?: Yes, URL encoding is fully reversible. Decoding replaces each percent-encoded sequence with the original character. The toggle in this tool lets you switch between encoding and decoding the same input.
Why does my URL break after encoding?: You likely used component encoding on a full URL, which encodes the ://, /, and ? characters. Switch to Full URL mode (the checkbox in this tool) to preserve the URL structure while encoding only the unsafe characters.