Codificador e Decodificador de URL

URLs were originally designed to transmit ASCII text over the internet. The URL specification (RFC 3986) reserves certain characters for special purposes: '?' separates the path from the query string, '&' separates parameters, '=' separates keys from values, '#' marks a fragment, and '/' separates path segments. When these characters appear in the data portion of a URL (like a search query or a parameter value), they must be encoded to avoid being interpreted as structural delimiters.

URL encoding (percent encoding) replaces each reserved or non-ASCII character with a percent sign (%) followed by two hexadecimal digits representing the character's byte value. For example, a space becomes %20, an ampersand becomes %26, and a forward slash becomes %2F. Characters in the unreserved set (A-Z, a-z, 0-9, hyphen, underscore, period, tilde) are never encoded. The JavaScript function encodeURIComponent() handles this encoding, while decodeURIComponent() reverses it.

Modern URLs also need to handle Unicode characters (emoji, CJK characters, accented letters). These are first encoded as UTF-8 bytes, then each byte is percent-encoded. For example, the coffee emoji 鈽?(U+2615) is encoded as UTF-8 bytes E2 98 95, which becomes %E2%98%95 in a URL. The browser and server automatically handle this encoding when you type a URL or submit a form, but developers often need to manually encode or decode URLs when building API endpoints, redirect URLs, or data URIs.

URL encoding is essential when passing data through URLs in web applications. Common scenarios include: building API query parameters (encoding search terms, filter values), creating redirect URLs that contain the original URL as a parameter (e.g., /login?redirect=%2Fdashboard), generating data URIs for embedded images or fonts, and encoding email links with subject and body parameters (mailto:?subject=...&body=...). OAuth flows also heavily rely on URL encoding for state parameters and callback URLs.

Um erro comum é a dupla codificação — codificar uma string já codificada. Por exemplo, codificar '%20' produziria '%2520' (o % é codificado como %25). Para evitar isso, sempre codifique strings decodificadas e decodifique strings codificadas. Nossa ferramenta detecta automaticamente se a string de entrada já está codificada e avisa você.ould produce '%2520' (the percent sign itself gets encoded to %25). Always decode before re-encoding if you're unsure of the string's current state. Another common issue is using encodeURI() instead of encodeURIComponent() -- encodeURI() does not encode reserved characters like ?, &, and =, making it unsuitable for encoding parameter values. Use encodeURIComponent() for individual parameter values and encodeURI() only for complete URLs.