Decodificador URL

Interaction with the web often involves "Percent-Encoding" to safely transmit data across the internet. However, these encoded strings—filled with %20 and %3F—are unreadable to humans and unusable for most backend logic. A URL Decoder is a high-precision tool that reverses the transformation defined in RFC 3986, transforming obfuscated data back into its original, meaningful form.

The decoding engine follows a rigorous technical workflow:

1. Percent-Sequence Identification: The tool scans the string for the percent sign (%). This is the signal that the following two characters represent a hexadecimal byte.
2. Hex-to-Binary Conversion: Every identified pair (e.g., 20, 26) is converted from hexadecimal back into a raw binary byte.
3. UTF-8 Byte Stream Assembly: The engine collects these bytes into a continuous stream. This is critical because modern characters (like Emojis or Kanji) are often composed of multiple bytes.
4. String Reconstruction: Using the UTF-8 Decoding Algorithm, the byte stream is transformed back into a standard Unicode string.
5. Malformed Sequence Handling: If the tool encounters an invalid sequence (like %G1, where G is not a valid hex digit), it provides a clear error message rather than a silent failure.

The History of URLs and Tim Berners-Lee

The requirement for URL decoding was born alongside the Web itself in 1994. Sir Tim Berners-Lee and the early W3C team realized that if URLs were to support the world's languages, they needed a way to translate complex symbols into the simple ASCII character set allowed by old internet routers.

The rules for this translation were first codified in RFC 1738 and reached their modern, robust form in RFC 3986, authored by Tim Berners-Lee, Roy Fielding, and Larry Masinter. Today, URL decoding is a fundamental operation in every Web Server and API Gateway, ensuring that the data you send in a search bar or contact form is correctly understood by the application.

Technical Comparison: URL Decoding vs. Base64 vs. HTML Entities

Understanding when and how to decode data is essential for preserving data integrity.

Feature	URL Decoding (RFC 3986)	Base64 Decoding (RFC 4648)	HTML Entity Decoding
Input Source	URL Query/Path	Binary Data in Text	HTML Document Source
Signal Char	Percent sign (%)	No Signal (Alphanumeric)	Ampersand (&)
Complexity	1 Hex pair per byte	4 Chars per 3 bytes	Named or Numeric
Common Use	API Parameter parsing	Image/JWT extraction	CMS Content editing
Integrity	High (Lossless)	High (Lossless)	Moderate (Visual)

By using a dedicated URL Decoder, you ensure that your data is RFC-Compliant, restoring the original intent of the sender with 100% precision.

Security Considerations: Injection and Malformed Input

URL decoding is a critical point of analysis for security professionals:

• Identifying "Double Encoding" Attacks: Attackers sometimes encode a payload twice (e.g., %253C instead of %3C) to bypass shallow security filters. Our decoder helps security researchers peel back these layers to reveal the underlying intent.
• Handling Payload Integrity: Failing to decode correctly can lead to Parameter Pollution. The tool ensures your logic sees the "real" character (like &) rather than a string literal.
• Client-Side Privacy: To maintain the highest Data Privacy standards, all decoding is performed locally on your machine. Your private tokens, user IDs, and secret API parameters are never transmitted to our servers.