Nix Image Optimizer helps optimize your WordPress media library by converting supported image uploads to WebP automatically and giving you tools to manage existing images, generate lightweight featured images, and improve image SEO metadata.
Features:
- Automatically converts new JPG, JPEG, PNG, and AVIF uploads to WebP.
- Bulk-compresses existing Media Library images.
- Shows compression statistics in a Media Log.
- Adds optional watermark support before compression.
- Generates blog-style featured images from post title, category, author name, and avatar.
- Supports custom featured image background colors, gradients, typography, and output dimensions.
- Auto-fills missing image ALT text and attachment descriptions from post content.
- Includes Basic and Advanced Image SEO Metadata modes.
- Scans and backfills existing posts with safe generated-metadata rules.
- Includes an unused media scanner and cleaner.
- Works with WordPress Media Library metadata and regeneration flow.
External services
This plugin can connect to the WordPress avatar system, which commonly uses Gravatar, when the Featured Image Generator is configured to include the post author’s avatar.
When the avatar option is enabled, the plugin requests the author’s avatar URL while showing the featured-image preview in the WordPress admin and while generating a featured image for a post or page. WordPress builds that avatar URL from the author’s user account email address according to the site’s normal avatar settings. The plugin downloads the avatar image from that URL so it can draw the circular author avatar into the generated featured image. If the avatar option is disabled, or if no avatar URL is available, the plugin does not request the avatar image and uses a local placeholder shape instead.
The avatar service is provided by Gravatar/Automattic:
Terms of Service: https://wordpress.com/tos/
Privacy Policy: https://automattic.com/privacy/
Screenshots
Settings tab with WebP quality controls.
Media Log showing compressed image statistics.
Bulk Compress progress interface.
Watermark settings and rebuild tools.
Unused Media Scanner and Cleaner.
Image SEO Metadata settings and backfill tools.
Featured Image Generator settings and post editor button.