About this plugin
CLU Just Modern Images brings WebP and AVIF to an existing WordPress image library without a separate thumbnail-regeneration step. Activate it and existing JPEG and PNG attachments are checked in the background, alongside new uploads.
Original images, existing thumbnails, attachment URLs, MIME types, and WordPress image metadata stay intact. Modern files are separate companions, served only when a complete, validated responsive set is available. Deactivating the plugin restores normal WordPress image output.
Images needed by a page rendered through WordPress move ahead of the remaining library scan. Visitors do not wait for conversion: it always happens in background jobs. Previously cached pages may bypass this prioritization.
The plugin is fully free, with no account, API key, or plugin-imposed image quota. Encoding takes place on your server and depends on its available resources and format support.
Activate the plugin and it will:
- verify what the server can really encode;
- process new JPEG and PNG Media Library uploads in the background;
- scan existing Media Library images automatically;
- create WebP and AVIF companions only when they are valid and smaller;
- serve complete responsive image sets through the picture element;
- keep the original image as the permanent fallback;
- prioritize new, manually selected, and currently needed images.
The plugin never replaces WordPress attachment filenames, MIME types, or core image metadata. Deactivation therefore restores normal WordPress image markup immediately.
The only preference is image quality: Economy, Standard, High, or Ultra. Server capability, conversion progress, and failure handling are automatic.
The interface follows your WordPress user language, or the site language when no user preference is set. Bundled translations cover Polish, German, French, Spanish, Italian, Brazilian Portuguese, Dutch, Czech, Ukrainian, and Japanese. English remains the fallback.
No language setting or external translation service is needed.
The settings screen gives one clear answer: images are taken care of, processing continues, or something needs attention. Progress measures completed checks, so keeping a smaller original or using only one modern format does not leave the library stuck at 99%. You can close the page at any time.
Image quality is an optional, collapsed preference. Server formats, processing counts, troubleshooting actions, and the activity log are kept under Help and details. Media Library rows also show individual results, with optional single-image and bulk priority actions.
When an image needs attention, the settings screen and Media Library show a plain-language explanation together with a stable diagnostic code. A server check can also be run directly from the settings screen. The Activity log keeps the latest 50 processing events with before-and-after library counts, server identifiers, stop reasons, and per-image results.
Administrators can download the same privacy-safe history as JSON for troubleshooting.
Designed to fail safely
Image encoding varies widely between hosting providers. CLU Just Modern Images performs a real capability probe and validates every generated file before it becomes eligible for use. Empty, corrupt, oversized, incomplete, or undecodable output is discarded.
Transparency is verified separately for AVIF and WebP. If a server encoder flattens transparent PNG files, that format remains available for ordinary photographs while transparent images automatically use another verified format or the original file.
WebP and AVIF are independent. If one encoder is missing or unstable, the other format continues to work. Repeated encoder failures temporarily pause only the affected format.
On installations served by more than one application server, capability results and encoder health are kept separately for each server environment. Generated companions use immutable names, so a verified active file is never overwritten during a quality refresh. Replaced files remain available for seven days to protect cached HTML before they are cleaned up.
No frontend conversion
Conversion never runs while a visitor is waiting for a page. Frontend filters only read a small attachment manifest and leave the original HTML unchanged when a complete modern source set is not ready.
When WordPress renders a page, attachments used by that response can move ahead of the background library scan. The plugin records only the attachment ID needed for processing. It does not store visitors, page URLs, view counts, cookies, or analytics data.
Fully cached responses may bypass WordPress and therefore do not provide this priority signal.
Privacy
The plugin processes images on your own server. It contains no analytics or remote diagnostic reporting mechanism and sends no reports to the developer or third-party services. Processing history stays in your WordPress database.
An administrator can download a local diagnostic report for troubleshooting and choose whether to share that file.