URL Encoder/Decoder

What is URL Encoding?

URL encoding (also called percent encoding) replaces characters that are not safe for use in URLs with their percent-encoded equivalents. For example, a space becomes %20, an exclamation mark becomes %21, and a forward slash becomes %2F. This encoding is necessary because URLs can only contain a limited set of ASCII characters — characters outside this set, or characters with special meaning in URLs (like ?, =, &, #), must be encoded to prevent misinterpretation.

The encoding follows the RFC 3986 standard, which defines which characters are reserved (have special URL meaning), unreserved (safe to use as-is), and which must be percent-encoded. URL encoding is bidirectional — encoding converts special characters to their percent-encoded form, and decoding reverses the process.

When Should You Encode or Decode URLs?

URL encoding is required when building API request URLs with query parameters containing special characters. Form data submitted via GET requests needs URL encoding. Redirect URLs containing user data need encoding. Any URL containing spaces, non-ASCII characters, or reserved characters in non-special positions must be encoded.

Developers debugging API integrations decode URLs to inspect query parameters. Frontend developers encode data for URL parameters. Backend developers decode incoming request URLs. Security analysts decode URLs to inspect encoded payloads. Anyone building or debugging web applications needs URL encoding/decoding capability.

How It Works

The encoder iterates through each character of the input string. Safe characters (letters, digits, - _ . ~) are passed through unchanged. Reserved characters and unsafe characters are replaced with their percent-encoded representation (%XX where XX is the hexadecimal character code). The decoder reverses this process, identifying %XX sequences and converting them back to the original characters. The tool handles both standard encoding and plus-character encoding (where spaces become + instead of %20).

Tips for Best Results

Do not encode the entire URL — only encode individual parameter values, not the URL structure itself. Preserve the query string delimiters (?, =, &) in their unencoded form. For form data, use application/x-www-form-urlencoded encoding where spaces become +. For path segments, use standard percent-encoding where spaces become %20.