application/x-www-form-urlencoded
The MIME type for URL-encoded form data submissions.
What Is This?
The application/x-www-form-urlencoded MIME type is the default encoding for HTML form submissions. It encodes form data as key-value pairs where keys and values are URL-encoded (spaces become +, special characters become %XX). This encoding is efficient for simple text data but inefficient for binary files.
Common Uses
Standard HTML form submissions without file uploads
OAuth 2.0 token endpoint requests
Simple API POST requests with key-value data
Legacy web application forms
Examples
Supported by all browsers. This is the default enctype for HTML forms.
The (none) file extension maps to application/x-www-form-urlencoded as its MIME type.
Related Entries
More from this reference:
application/json
The standard MIME type for JavaScript Object Notation (JSON) data interchange.
application/pdf
The MIME type for PDF (Portable Document Format) documents.
application/zip
The MIME type for ZIP archive files used for compression and bundling.
application/xml
The MIME type for XML documents and data interchange.
Frequently Asked Questions
Why is this encoding inefficient for binary data?
Binary data must be base64-encoded when sent as application/x-www-form-urlencoded, which increases the size by 33%. For file uploads, use multipart/form-data instead, which sends binary data more efficiently.
What is the size limit for URL-encoded data?
Most servers have a configurable limit (typically 1-8 MB) for URL-encoded request bodies. The URL length itself is limited to about 8 KB in most browsers and servers.