Krystian Gacek Image Format Converter

Krystian Gacek Image Format Converter makes your images smaller without touching them. For every JPEG and PNG in the Media Library it creates a WebP and an AVIF version next to the original (photo.jpg → photo.jpg.webp, photo.jpg.avif) and shows each visitor the smallest format their browser can display. The original file is never modified or deleted.

Everything happens on your own server — no external service, no account, no monthly image limit.

What sets it apart:

• Local conversion only. Images never leave your server, so there are no quotas, API keys or per-image costs.
• Originals stay untouched. Versions are separate files; deleting the plugin can remove them and leaves the originals as they were.
• No double work when switching. WebP/AVIF files already made by Converter for Media are taken over instead of being converted again.
• An estimate before you start. The plugin encodes a sample of your own images and shows how much smaller the library will be.
• A profile for line art. Drawings and coloring pages get settings that keep thin lines sharp at a small file size.

How it works

• Your library is converted in the background. The plugin finds every image and every thumbnail size, then converts them in short steps (WP-Cron), so the site stays fast. While the plugin screen is open, conversion runs faster and you can watch the live progress: files left, speed, time left and the file being converted right now.
• New uploads are converted automatically, a minute or two after upload, without slowing down the upload itself.
• Pages get a <picture> element with AVIF and WebP sources. The original <img> stays as the fallback, so every browser shows the image and search engines keep indexing the original address. This standard <picture> delivery method works without server rewrite rules and is compatible with most caching setups.
• A version is kept only when it is smaller than the original by the margin you choose; otherwise browsers simply get the original.

Features

• WebP and AVIF, each can be switched on or off
• Quality profiles for photos, line art (e.g. coloring pages) and maximum saving, or your own numbers — with a before/after comparison on your own images
• Automatic choice of the best encoder the server has: PHP GD, Imagick, or the cwebp / avifenc programs — every encoder is tested on the server first
• Takes over the WebP/AVIF files already made by Converter for Media (wp-content/uploads-webpc), so nothing is converted twice when you switch
• Estimate of the saving before the first conversion, measured on a sample of your images
• Dashboard with savings, per-format counts, errors and recently converted files
• Media Library column with the state of every image, “Convert now”, “Convert again”, “Delete WebP/AVIF” and bulk actions
• Tools: server test, delivery test, cleanup of versions whose original is gone, deleting all versions
• Log with filters and CSV export, statistics per image size and over time
• Process limits and a gentle mode for shared hosting
• Optional server rules (.htaccess) that serve versions at the original addresses — for images outside the content; behind Cloudflare they need a Cache Rule that varies on the Accept header, and the plugin warns you about it
• WP-CLI: wp kgifc status, start, run --until-done, pause, resume, regenerate, probe, cleanup, delete-versions

Local command-line encoders

Krystian Gacek Image Format Converter can optionally use the locally installed cwebp and avifenc command-line programs when they are available on the server.

These programs are not bundled with the plugin and are not downloaded by the plugin. They are executed locally on the WordPress server.

If they are unavailable, the plugin can use PHP GD or Imagick when the requested image format is supported by the server.

Privacy

The plugin does not send images or conversion data to external image-processing services. The delivery test requests a converted file from your own site to check its content type.