The URL tool has two halves. One calls the browser's own encodeURIComponent / decodeURIComponent or encodeURI / decodeURI to encode and decode a string. The other uses the native URL / URLSearchParams objects to take a full address apart and edit its query parameters. Parsing an address never visits the site behind it.

1. 01In the encoding panel choose “Component” or “Full URI”, then encode or decode.
2. 02Paste a string and the result appears immediately; an illegal % escape raises an error.
3. 03In the parsing panel enter a full URL with a scheme and read protocol, host, hostname, port, pathname, hash and origin.
4. 04Edit, add or delete query parameters and the URL is re-serialised by the URLSearchParams rules.

• “Component” and “Full URI” are two different native APIs with different reserved-character sets; their results are not interchangeable encodings.
• decodeURI* throws on a truncated % or an invalid UTF-8 percent sequence; the tool does not try to guess a repair.
• URL parsing needs an absolute address that new URL() accepts; a bare domain without https://, for instance, reports a format error.
• Query parameters are rebuilt with URLSearchParams.toString(), so spaces, repeated keys and escape forms may be normalised; a byte-for-byte round trip is not guaranteed.
• The tool only parses and rewrites strings: no DNS lookups, no HTTP requests, no link-availability checks.

The URL and parameters you enter are processed in the browser only; no request is sent to the host inside them or to any third-party service.