Warp-iMagick

Warp iMagick - WebP Converter JPEG/PNG Compressor - Free Plugin 4 WordPress: Optimize Images on-site. No cloud-optimization-service. Convert to WebP - On-Upload, On-Regenerate, On Demand (v2.+). Set JPEG Quality and Sharpness. Set Big Image Threshold and Resize on Upload. Maintained by ddur on GitHub, where it has earned 36 stars from the community.

It's actively developed around wordpress-plugin, image-optimization, image-optimisation, and is a solid reference for anyone building with these tools.