Formencoded

Formencoded refers to data encoded using the application/x-www-form-urlencoded media type, a standard method for submitting HTML form data. In this format, the form’s key-value pairs are serialized into a single string where each pair appears as name=value and pairs are separated by ampersands. Within each pair, characters are URL-encoded: alphanumeric characters remain as-is, spaces are represented as plus signs, and other characters are percent-encoded. The resulting string is typically placed in the body of an HTTP POST request, or in the query component of a URL for GET requests.

The encoding is defined by HTML specifications and is widely supported by web servers and frameworks. When a form uses method=POST and the default enctype, the data is sent in this form-encoded format in the request body. If a form uses method=GET, the same encoding is used to append the data to the URL’s query string. This approach is simple and efficient for small amounts of textual data and for forms that do not involve binary content.

Limitations and alternatives: form-encoded data is not well suited for binary data or large files; for those cases, multipart/form-data is used. For APIs and richer data structures, JSON is a common alternative. Security considerations include the fact that form-encoded data in the URL or query strings can be logged or cached; sensitive information should be transmitted only over HTTPS and avoided in URLs when possible. Server-side frameworks typically provide built-in parsing to convert the encoded string back into key-value mappings.