Quick tutorial for USP Pro about controlling which types of files are allowed in user-submitted forms. It is important to understand that USP Pro uses WordPress’ Media Library feature to handle submitted files. So the underlying functionality is the same regardless of where or how files are uploaded/submitted. In other words, files submitted via any USP Pro Form are handled the same way as files uploaded via the WP Media Library.

Defining which file types are allowed

USP Pro provides both global (default) and local (form specific) ways of specifying which file types are allowed in any USP Pro Form. In a nutshell, you can allow any of the file types that are supported by WordPress. So with that in mind, here are instructions explaining how to allow/restrict file types globally and/or locally.

Global Setting

Visit Allowed File Types in the Uploads Settings and indicate any file types that will be accepted by any USP Form.

Local Setting

Once the global setting is configured, it is possible to fine-tune for specific forms. To do so, add the types attribute to the [usp_files] shortcode, like so:

[usp_files types="pdf,docx"]

In this example, we are explicitly allowing the specific form to accept both PDF and DOCX, while excluding all other file types (even if they are specified/allowed in the global settings).

Note: The types attribute also can be used to specify file types when defining custom fields. Check the shortcode reference for details.

List of file types supported by WordPress

At the time of this writing, WordPress (and USP Pro) support the following file formats. Note that the file extension is given in the left column, and the file header/type in the right column):

	// Image formats
	'jpg|jpeg|jpe'                 => 'image/jpeg',
	'gif'                          => 'image/gif',
	'png'                          => 'image/png',
	'bmp'                          => 'image/bmp',
	'tif|tiff'                     => 'image/tiff',
	'ico'                          => 'image/x-icon',
	'webp'                         => 'image/webp',
	'heic'                         => 'image/heic',
	'heif'                         => 'image/heif',
	'svg'                          => 'image/svg+xml',

	// Video formats
	'asf|asx'                      => 'video/x-ms-asf',
	'wmv'                          => 'video/x-ms-wmv',
	'wmx'                          => 'video/x-ms-wmx',
	'wm'                           => 'video/x-ms-wm',
	'avi'                          => 'video/avi',
	'divx'                         => 'video/divx',
	'flv'                          => 'video/x-flv',
	'mov|qt'                       => 'video/quicktime',
	'mpeg|mpg|mpe'                 => 'video/mpeg',
	'mp4|m4v'                      => 'video/mp4',
	'ogv'                          => 'video/ogg',
	'webm'                         => 'video/webm',
	'mkv'                          => 'video/x-matroska',
	// Text formats
	'txt|asc|c|cc|h'               => 'text/plain',
	'csv'                          => 'text/csv',
	'tsv'                          => 'text/tab-separated-values',
	'ics'                          => 'text/calendar',
	'rtx'                          => 'text/richtext',
	'css'                          => 'text/css',
	'htm|html'                     => 'text/html',
	// Audio formats
	'mp3|m4a|m4b'                  => 'audio/mpeg',
	'ra|ram'                       => 'audio/x-realaudio',
	'wav'                          => 'audio/wav',
	'ogg|oga'                      => 'audio/ogg',
	'mid|midi'                     => 'audio/midi',
	'wma'                          => 'audio/x-ms-wma',
	'wax'                          => 'audio/x-ms-wax',
	'mka'                          => 'audio/x-matroska',
	// Misc application formats
	'rtf'                          => 'application/rtf',
	'js'                           => 'application/javascript',
	'pdf'                          => 'application/pdf',
	'swf'                          => 'application/x-shockwave-flash',
	'class'                        => 'application/java',
	'tar'                          => 'application/x-tar',
	'zip'                          => 'application/zip',
	'gz|gzip'                      => 'application/x-gzip',
	'rar'                          => 'application/rar',
	'7z'                           => 'application/x-7z-compressed',
	'exe'                          => 'application/x-msdownload',
	// MS Office formats
	'doc'                          => 'application/msword',
	'pot|pps|ppt'                  => 'application/vnd.ms-powerpoint',
	'wri'                          => 'application/vnd.ms-write',
	'xla|xls|xlt|xlw'              => 'application/vnd.ms-excel',
	'mdb'                          => 'application/vnd.ms-access',
	'mpp'                          => 'application/vnd.ms-project',
	'docx'                         => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
	'docm'                         => 'application/vnd.ms-word.document.macroEnabled.12',
	'dotx'                         => 'application/vnd.openxmlformats-officedocument.wordprocessingml.template',
	'dotm'                         => 'application/vnd.ms-word.template.macroEnabled.12',
	'xlsx'                         => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
	'xlsm'                         => 'application/vnd.ms-excel.sheet.macroEnabled.12',
	'xlsb'                         => 'application/vnd.ms-excel.sheet.binary.macroEnabled.12',
	'xltx'                         => 'application/vnd.openxmlformats-officedocument.spreadsheetml.template',
	'xltm'                         => 'application/vnd.ms-excel.template.macroEnabled.12',
	'xlam'                         => 'application/vnd.ms-excel.addin.macroEnabled.12',
	'pptx'                         => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
	'pptm'                         => 'application/vnd.ms-powerpoint.presentation.macroEnabled.12',
	'ppsx'                         => 'application/vnd.openxmlformats-officedocument.presentationml.slideshow',
	'ppsm'                         => 'application/vnd.ms-powerpoint.slideshow.macroEnabled.12',
	'potx'                         => 'application/vnd.openxmlformats-officedocument.presentationml.template',
	'potm'                         => 'application/vnd.ms-powerpoint.template.macroEnabled.12',
	'ppam'                         => 'application/vnd.ms-powerpoint.addin.macroEnabled.12',
	'sldx'                         => 'application/vnd.openxmlformats-officedocument.presentationml.slide',
	'sldm'                         => 'application/vnd.ms-powerpoint.slide.macroEnabled.12',
	'onetoc|onetoc2|onetmp|onepkg' => 'application/onenote',
	// OpenOffice formats
	'odt'                          => 'application/vnd.oasis.opendocument.text',
	'odp'                          => 'application/vnd.oasis.opendocument.presentation',
	'ods'                          => 'application/vnd.oasis.opendocument.spreadsheet',
	'odg'                          => 'application/vnd.oasis.opendocument.graphics',
	'odc'                          => 'application/vnd.oasis.opendocument.chart',
	'odb'                          => 'application/vnd.oasis.opendocument.database',
	'odf'                          => 'application/vnd.oasis.opendocument.formula',
	// WordPerfect formats
	'wp|wpd'                       => 'application/wordperfect',
	// iWork formats
	'key'                          => 'application/vnd.apple.keynote',
	'numbers'                      => 'application/vnd.apple.numbers',
	'pages'                        => 'application/vnd.apple.pages',

Again, check the WordPress documentation for the latest information regarding supported file types.

Take-home message

The point of this tutorial is that file types must be specified in the global settings in order to be accepted during submission from any form. Then once you have added all file types to the global settings, you can further restrict which ones are accepted for each specific post as needed. Or, if the type attribute is blank or not included in the [usp_files] shortcode, the plugin will fallback to the global settings.