Frequently Asked Questions

Everything people ask about URL encoding and about how url-decoder.net works. Missing something? Ask us directly.

What is URL encoding?

URL encoding (percent-encoding) replaces characters that are unsafe or reserved in URLs with a percent sign followed by two hexadecimal digits. A space becomes %20 and an ampersand becomes %26. It is defined in RFC 3986 and is required whenever data travels inside a URL.

Is my data safe in this tool?

Yes. All encoding, decoding, and parsing runs locally in your browser with JavaScript. Nothing you type, paste, or upload is sent to a server. You can disconnect from the internet after the page loads and the tool keeps working.

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

%20 is the percent-encoded space defined by RFC 3986 and is always correct in URLs. The plus sign only means a space inside application/x-www-form-urlencoded data, such as HTML form submissions and many query strings. In a path, a plus sign is just a literal plus. When in doubt, use %20.

What is the difference between encodeURI and encodeURIComponent in JavaScript?

encodeURIComponent encodes everything that is not an unreserved character, so it is right for individual values like a query parameter. encodeURI leaves reserved separators such as /, ?, and & intact, so it is only useful for encoding a complete URL without breaking its structure. This tool behaves like encodeURIComponent.

Why does my decoded text show strange characters like é?

That is almost always a character set mismatch: the bytes were encoded as UTF-8 but decoded as a single-byte charset, or the other way round. Try switching the character set selector between UTF-8, ISO-8859-1, and Windows-1252 until the text looks right.

What is double encoding and how do I fix it?

Double encoding happens when already-encoded text is encoded again, turning %20 into %2520 because the % itself gets encoded as %25. To fix it, decode the text repeatedly until no percent sequences remain, then encode exactly once at the final step.

Which characters never need encoding?

The unreserved set from RFC 3986: the letters A to Z and a to z, the digits 0 to 9, and the four symbols hyphen (-), underscore (_), period (.), and tilde (~). Everything else should be percent-encoded when used as data in a URL.

Is there a maximum URL length?

No formal limit exists in the standard, but practical limits do: many browsers and servers handle around 2,000 characters reliably, and some systems cap at 8,192 bytes. If your encoded URL grows beyond that, consider sending the data in a request body instead.

Can I encode or decode many URLs at once?

Yes. Turn on the 'Process each line separately' checkbox and paste one URL per line, or upload a .txt file. Each line is converted independently and you can download the full result as a text file.

Does this tool work offline?

Once the page has loaded, yes. All logic ships with the page and runs in your browser, so an interrupted connection does not stop the tool from working.