Cool AVIF: Image Conversion Plugin for WordPress to AVIF, WebP, HEIC, and JXL

Stack: WordPress PHP ImageMagick GD AVIF WebP HEIC JXL GNU GPL v2

Co-authors: Paweł Potacki, Pijush Gupta

The Problem

Large JPG and PNG files can noticeably slow down a WordPress website. Manual image conversion becomes inconvenient when the media library contains older uploads and multiple variants generated by WordPress.

What I Built

Cool AVIF is an open-source plugin that converts images locally on the server. Depending on the environment, it uses ImageMagick or GD. It can process both new uploads and existing assets already stored on the website.

Main Features

conversion to WebP and AVIF, with additional formats available when supported by the ImageMagick setup,
bulk processing for the media library, themes, plugins and selected cache directories,
support for common input formats such as JPG, PNG and WebP,
server rewrite rules for serving an appropriate image variant,
open-source code available on GitHub.

Why I Built It

I wanted a practical tool that could run inside the existing hosting environment without making basic image conversion dependent on a paid external service. This is especially useful for websites with larger media libraries or projects where image optimization is part of ongoing maintenance.

Availability

The project is developed as open-source software under the GNU GPL v2 license. The code and installation notes are available on GitHub.