Images to WebP Reviews, Downloads & Maintenance

Statistics say that WebP format can save over a half of the page weight without losing images quality.
Convert PNG, JPG and GIF images to WebP and speed up your web, save visitors download data, make your Google ranking better.

automated test after plugin activation to make sure it will work on your server
works with all types of WordPress installations: domain, subdomain, subdirectory, multisite/network
works on Apache and NGiNX
image URL will be not changed so it works everywhere, in src, srcset, , even in CSS backgrounds and there is no problem with cache
original files will be not touched
set quality of converted images
auto convert on upload
only convert image if WebP filesize is lower than original image filesize
bulk convert existing images to WebP ( you can choose folders )
bulk convert only missing images
works with `Fly Dynamic Image Resizer` plugin

Hooks for developers

itw_extensions

Maybe you want to support also less famous JPEG extension like jpe, jfif or jif

add_filter( 'itw_extensions', 'extra_itw_extensions', 10, 1 );
function extra_itw_extensions( $extensions ){
    $extensions[] = 'jpe';
    $extensions[] = 'jfif';
    $extensions[] = 'jif';
    return $extensions;
}

itw_sizes

Maybe you want to disable WebP for thumbnails

add_filter( 'itw_sizes', 'disable_itw_sizes', 10, 2 );
function disable_itw_sizes( $sizes, $attachmentId ){
    unset( $sizes['thumbnail'] );
    return $sizes;
}

itw_htaccess

Maybe you want to modify htaccess rules somehow

add_filter( 'itw_htaccess', 'modify_itw_htaccess', 10, 2 );
function modify_itw_htaccess( $rewrite_rules ){
    // do some magic here
    return $rewrite_rules;
}

itw_abspath

Maybe you use roots.io/bedrock or other custom folder structure

add_filter( 'itw_abspath', 'modify_itw_abspath', 10, 2 );
function modify_itw_abspath( $abspath ){
    return trailingslashit( WP_CONTENT_DIR );
}

$images_to_webp->convert_image()

Maybe you want to automatically generate WebP for other plugins

add_action( 'XXPLUGIN_image_created', 'XX_images_to_webp', 10, 2 );
function XX_images_to_webp( $image_path ){
    global $images_to_webp;
    $images_to_webp->convert_image( $image_path );
}

Installation

Upload images-to-webp directory to the /wp-content/plugins/ directory
Activate the plugin through the ‘Plugins’ menu in WordPress

Frequently Asked Questions

Plugin requirements

It should work almost everywhere 😉
PHP 5.6 or higher
GD or Imagick extension with WebP support
Enabled server modules: mod_mime, mod_rewrite

WebP images stored location

WebP images are generated in same directory as original image. Example:
original img: /wp-content/uploads/2019/11/car.png
webp version: /wp-content/uploads/2019/11/car.png.webp

How to get original image from the browser?

Just add ?no_webp=1 to the URL and original JPG/PNG will be loaded

How to check if plugin works?

When you have installed plugin and converted all images, follow these steps:

Run Google Chrome and enable Dev Tools (F12).
Go to the Network tab click on Disable cache and select filtering for Img (Images).
Refresh your website page.
Check list of loaded images. Note Type column.
If value of webp is there, then everything works fine.

NGiNX and Apache together

If you have some proxy setup or some other combination of NGiNX and Apache on your server, then probably .htaccess changes won’t work and you will need to ask your hosting provider to disable NGiNX direct processing of image static files.

Apache .htaccess

Plugin should automatically update your .htaccess with needed rules.
In case it’s not possible to write them automatically, screen with instructions will appear.
Anyway, here is how it should look like:

<IfModule mod_mime.c>
    AddType image/webp .webp
</IfModule>

<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteCond %{HTTP_ACCEPT} image/webp
    RewriteCond %{REQUEST_FILENAME} "/"
    RewriteCond %{REQUEST_FILENAME} "\.(jpg|jpeg|png|gif)$"
    RewriteCond %{REQUEST_FILENAME}\.webp -f
    RewriteCond %{QUERY_STRING} !no_webp
    RewriteRule ^(.+)$ $1\.webp [NC,T=image/webp,E=webp,L]
</IfModule>

NGiNX config

After you activate plugin, screen with instructions will appear.
Anyway, here is how it should look like:

You need to add this map directive to your http config, usually nginx.conf ( inside of the http{} section ):

map $arg_no_webp $no_webp{
    default "";
    "1" "no_webp";
}

map $http_accept $webp_suffix{
    default "";
    "~*webp" ".webp";
}

or without map directive:

if ( $http_accept ~ "image/webp" ) {
    set $webp .webp ;
}

location ~* (.*)\.(?:png|jpe?g|gif)$ {
    if ( -f $document_root$1.webp ) {
            set $webp serve$webp ;
    }
    if ( $webp = "serve.webp" ) {
        return 301 '$1.webp';
    }
}

then you need to add this to your server block, usually site.conf or /nginx/sites-enabled/default ( inside of the server{} section ):

location ~* ^/.+\.(png|gif|jpe?g)$ {
    add_header Vary Accept;
    try_files $uri$webp_suffix$no_webp $uri =404;
}

ISP Manager

Are you using ISP Manager? Then it’s probably not working for you, but no worries, you just need to go to WWW domains and delete jpg|jpeg|png from the Static content extensions field.

Delete all generated WebP images

There is no button to do that and it will also not delete generated WebPs automatically when you deactivate the plugin, but if you really need this, you can run some shell command to achieve this:

find . -type f -name "*.webp" -exec bash -c 'if [ -f "${1%.webp}" ]; then echo "Deleting $1"; rm "$1"; fi' _ {} \;

This will find all the files with a .webp extension and if there is similar file with the exact filename, but without the .webp extension, then it will delete it.

Review feed

szelpe

12/28/2021

Great

Nice work, thank you.

Screenshots

Changelog

4.8

Tested on WP 6.9

4.7

Tested on WP 6.5

4.6

Fix for “Find and convert MISSING images” button

4.5

Tested on WP 6.4
added FAQ section “Delete all generated WebP images”

4.4

Tested on WP 6.3
added FAQ section “NGiNX and Apache together”
make configs error messages more descriptive

4.3

Tested on WP 6.2
new filter itw_abspath for WP installations with customized folder structure like Bedrock

4.2

make convert old works also for local installations

4.1

fix – convert also all subdirectories

4.0

lazy load folders in convert tab
make it works for local installations like XAMPP or Flywheel Local
try-catch conversion errors
updated jstree library

3.1

add ?no_webp=1 to URL to receive original image content from Nginx server

3.0

Tested on WP 6.1
added support for Better image sizes plugin
add ?no_webp=1 to URL to receive original image content – works only on Apache and only with direct image URL

2.0

Tested on WP 6.0
convert and serve WebP images anywhere – not only in wp-content folder
option to delete original images after conversion

1.9.1

Tested on WP 5.9

1.9

Tested on WP 5.8
added some nonce checks and more security validations
better nginx instructions

1.8

Tested on WP 5.7
add more CURL options
fix backslashes for localhosts

1.7

Tested on WP 5.6
fixed problem on some multisites

1.6

Tested on WP 5.4
added support for Fly Dynamic Image Resizer plugin

1.5

notice when test image is not accessible

1.4

new test method

1.3

fixed text domain for translations

1.2

added instructions for NGiNX

1.1

make it works in multisite and subdirectory installs

1.0

First version

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