Compatibility

File types

ImgCrisp optimizes JPEG, PNG, WebP and AVIF images up to 50 MB. GIF, SVG, HEIC, TIFF and other types are left as they are and show as Skipped in the report, with the reason.

Themes

ImgCrisp works through WordPress’s own image functions, so it reaches images in post and page content and images a theme prints with those functions, in any theme. When a theme prints a full-size image with no smaller sizes on offer, ImgCrisp adds the sizes WordPress already made, so phones get a smaller file.

An image a theme writes straight into its HTML, without WordPress’s image functions, isn’t changed. Neither are CSS background images.

Page builders

Images a page builder outputs through WordPress’s image functions are served the lighter files like any other. The Image Scanner and the Upscale scan only read the standard post content, so they don’t see layouts a builder stores elsewhere.

Yoast SEO

ImgCrisp handles Yoast SEO directly. Share images for Facebook and X, schema images, and image sitemaps point at the lighter JPEG version of a photo-like PNG, so crawlers and social platforms stop downloading large PNGs. Other SEO plugins get no special handling.

WooCommerce

Product images are ordinary WordPress images, so they are optimized and served like any other. ImgCrisp has no WooCommerce-specific features.

CDNs and offloaded media

ImgCrisp serves WebP and AVIF only for images stored in your site’s own uploads folder. If a plugin moves your media to cloud storage or rewrites image addresses to a CDN’s domain, ImgCrisp won’t switch those images to the lighter formats.

Multisite

ImgCrisp isn’t built or tested for WordPress multisite networks yet.

Command line

ImgCrisp has one WP-CLI command, wp imgcrisp diag, which prints the diagnostics file. Add --pretty to make it readable, or --file=<path> to save it. See Troubleshooting.