From wordpress version 5.8, webp is supported by default. Anyways add the below code snippet in your active theme's functions.php
file.
function add_custom_upload_mimes( $mimes_types ) {
$mimes_types['webp'] = 'image/webp'; // webp files
return $mimes_types;
}
add_filter( 'upload_mimes', 'add_custom_upload_mimes' );
function add_allow_upload_extension_exception( $types, $file, $filename, $mimes ) {
// Do basic extension validation and MIME mapping
$wp_filetype = wp_check_filetype( $filename, $mimes );
$ext = $wp_filetype['ext'];
$type = $wp_filetype['type'];
if( in_array( $ext, array( 'webp' ) ) ) { // if follows webp files have
$types['ext'] = $ext;
$types['type'] = $type;
}
return $types;
}
add_filter( 'wp_check_filetype_and_ext', 'add_allow_upload_extension_exception', 99, 4 );
function displayable_image_webp( $result, $path ) {
if ($result === false) {
$displayable_image_types = array( IMAGETYPE_WEBP );
$info = @getimagesize( $path );
if (empty($info)) {
$result = false;
} elseif (!in_array($info[2], $displayable_image_types)) {
$result = false;
} else {
$result = true;
}
}
return $result;
}
add_filter( 'file_is_displayable_image', 'displayable_image_webp', 10, 2 );