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Development Utility

URL Encoder & Decoder

Encode standard characters into URL percent-escaped representations, or decode escaped query strings back to human-readable text blocks.

Plain Text / URL Input
Encoded URL Result

Understanding URL Percent-Encoding Standards

The Uniform Resource Locator, commonly known as a URL, is the global address system for web assets. According to standard Internet Engineering Task Force (IETF) RFC specifications, a URL must contain only a very narrow set of safe characters. Any character outside this safe boundary must be converted to a percent-encoded representation before being transmitted.

Reserved vs. Unreserved Characters

Characters in URLs are classified into two primary categories:

  • Unreserved: Letters (A-Z, a-z), digits (0-9), and hyphen (-), underscore (_), period (.), and tilde (~). These never require encoding.
  • Reserved: Characters that have special syntax meanings (e.g. ? for queries, & for parameters, / for paths). If they are used as actual data values rather than markers, they must be encoded.

How Percent Encoding Works

Percent-encoding converts non-ASCII or reserved characters into a sequence of bytes, with each byte represented by a percent sign (%) followed by its two-digit hexadecimal value. For example:
- A space character is encoded as %20.
- An ampersand (&) is encoded as %26.
- A slash (/) is encoded as %2F.

Frequently Asked Questions (FAQs)

Why do URLs require percent-encoding?

URLs can only carry specific characters from the basic ASCII character set. Special symbols like spaces, question marks, slashes, and ampersands have specific meanings in URL syntax. If you want to carry these characters safely within query values, they must be escaped.

What does encodeURIComponent do?

It is a native JavaScript function that escapes all special characters (except alphabets, numbers, and symbols like - _ . ! ~ * ' ( )). It converts spaces to %20 and translates other symbols into their specific hexadecimal equivalents.

How does decoding detect invalid inputs?

URL percent-decoding expects every percentage symbol (%) to be followed by exactly two hexadecimal digits (0-9, A-F) representing a byte coordinate. A loose % sign without digits will throw a fatal URI decoding error, which our validator catches.

How to Use This Tool

  1. 1Toggle your desired operation mode (Encode URL strings or Decode URL strings).
  2. 2Paste your URL address or query parameter block into the left-hand editor box.
  3. 3Click 'Convert & Process' to convert spaces, slashes, and symbols into percent coordinates.
  4. 4Review results in the right output panel. Identify syntax validation errors inside red alert logs.
  5. 5Use the copy button to fetch your processed URLs instantly.