URL Encoder Decoder

Why URLs need encoding at all

A URL can only safely contain a limited set of characters — letters, digits and a handful of punctuation marks. Anything else (spaces, accented letters, symbols like & or ?) has to be percent-encoded into a safe escape sequence, or it risks being misread as part of the URL's structure rather than as data. This is exactly what happens automatically when you paste a search query with spaces into a browser's address bar.

Why certain characters are "reserved" and need escaping

Characters like ?, &, =, and / have special structural meaning in a URL - they separate the path from the query string, or separate one query parameter from the next. If your actual data contains one of these characters literally (a search term that happens to include an ampersand, for instance), it must be percent-encoded, or it would be misinterpreted as a structural separator instead of as part of your data.

Why decoding sometimes fails

Decoding expects a valid, well-formed percent-encoded sequence - a stray % not followed by two valid hexadecimal digits, or a truncated sequence from text that was copied incompletely, will cause decoding to fail with an error rather than guessing at what was intended. This is a safety feature: silently guessing wrong could corrupt data rather than flag the problem.

Why this matters beyond just pasting into a browser

Percent-encoding comes up constantly in web development and API work - building query strings programmatically, passing data through webhook URLs, or debugging why a parameter with special characters isn't being read correctly by a server. Manually encoding or decoding by hand is error-prone, which is where a dedicated tool like this one saves time.

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Why does a space become %20 instead of +?

This tool's Encode button always escapes a space as %20, and Decode mirrors that — %20 comes back as a space, but a literal + is left as a plus sign rather than converted to a space. The +-means-space convention belongs specifically to form-urlencoded query strings (the format HTML forms submit), not to general percent-encoding, which is why this general-purpose tool doesn't apply it.

Is this the same as Base64 encoding?

No — URL encoding (percent-encoding) escapes unsafe characters for use inside a URL, while Base64 encodes arbitrary binary data into text. They solve different problems.

Why do certain characters need escaping in a URL?

Characters like ? and & have structural meaning (separating the path from the query string, or one parameter from the next) - if your actual data contains one of them literally, it must be encoded so it isn't misread as structure.

Why did decoding fail on my input?

Decoding requires a valid, well-formed percent-encoded sequence. A stray % not followed by two hex digits, or text copied incompletely, will cause an error rather than a guessed (and possibly wrong) result.

When would I need this outside of pasting a link in a browser?

It comes up often in web development - building query strings programmatically, passing data through webhook URLs, or debugging why a parameter with special characters isn't read correctly by a server.