URL decoder

Decode a URL-encoded string back to its original text.

0 of 0 ratings

URL Decoder: Decoding Encoded URLs

A URL decoder reverses the process of URL encoding. It takes a percent-encoded string and converts it back to its original form, replacing %XX sequences with the characters they represent. This is useful for reading URLs that have been encoded, debugging query strings, and extracting data from encoded parameters.

How URL Decoding Works

The decoder scans the input for percent signs followed by two hexadecimal digits. Each such sequence is replaced by the corresponding byte. The resulting bytes are then interpreted according to the character encoding (usually UTF-8). Additionally, + is sometimes decoded as a space, depending on the context (form data vs. URL path).

Common Uses of URL Decoding

Analyzing query strings: When debugging, you often need to see the actual values passed in a URL.
Extracting data from encoded URLs: If you have a URL with encoded parameters, decoding reveals the original values.
Working with form data: Form submissions are URL-encoded, and decoding recovers the original input.
Log analysis: Web server logs contain encoded URLs; decoding makes them readable.

URL Decoding Errors

If the input contains invalid percent sequences (e.g., %ZZ or a truncated sequence), decoding may fail or produce unexpected results. Some decoders are lenient and leave invalid sequences as-is; others throw errors. Always ensure the input is valid URL-encoded data.

Decoding vs. Decrypting

URL decoding is not decryption. It is a reversible transformation that anyone can perform. It provides no security. If sensitive data is in a URL, it should be encrypted before encoding, and the URL should use HTTPS to protect it in transit.

Practical Example

Decoding hello%20world returns hello world. Decoding price%3D100%26currency%3DUSD returns price=100¤cy=USD. Decoding %C3%BC returns ü.

Conclusion

URL decoding is a simple but essential operation for working with encoded URLs. It reverses the encoding process and restores the original data. Use it whenever you need to read or process URL-encoded strings.