rodrigosilvano

This plugin converts JPEG/JPG/PNG to WebP at upload time—before WordPress generates sub-sizes. Supports Imagick (preferred) and GD (fallback). Options for quality, PNG lossless, and delete original.

RS Auto WebP Convert

Automatically converts JPEG/JPG/PNG to WebP on upload, with an option to delete the original. Imagick preferred, GD fallback. No tracking.

steveturner2018

Media Webp has been designed to help you fully automate the management of webp images on your WordPress website. 
When a compatible image is uploaded to your sites media library corresponding webp images will be generated. Giving you the advantages of webp images without having to maintain matching images yourself. 
This plugin also updates any existing webp images if the associated attachment image is altered through the admin interface. 
Included is the option to allow this plugin to generate webp images for your theme when it is made active or switched too. 
The plugin has built in tools to generate webp files from existing images both within your upload media and the active theme folders. 
Too enable your server to send webp images you will need to include a small block of code at the top of your .htaccess file. This will allow your server to check if the requesting browser accepts webp images and if there is a corresponding webp image. Full instructions are available on the settings page.
What this plugin does NOT do.
Alter any existing images that do not have the webp extension. 
Delete any images that do not have the webp extension. 
Alter any .htaccess file(s) for you.

Media Webp

This plugin resolves the conversion to webp very easily. It only needs a couple of errors to solve. Congratulations!!

Fantastic

Automatically creates webp images when you upload compatible media.  This plugin also manages any updates and changes to the linked attachment images.

RS Auto WebP Convert vs Media Webp