Codcy

Codcy Image Optimizer converts your existing JPEG and PNG images to WebP format in bulk — directly on your server, with no third-party API or paid subscription required.
WebP images are significantly smaller than JPEG and PNG files (typically 60–95% smaller), which leads to faster page loads, lower bandwidth usage, and better Core Web Vitals scores.
How it works:
<ol>
<li>Scan — Analyzes your entire Media Library. Shows total image count, file size, and format breakdown before any changes are made.</li>
<li>Review — You decide when to start. Nothing is changed until you click Start.</li>
<li>Optimize — Converts images in batches of 20. Originals are backed up automatically.</li>
<li>Report — A detailed summary shows converted count, space saved, average compression rate, and any errors.</li>
</ol>
Key features:
<ul>
<li>Converts JPEG and PNG to WebP</li>
<li>Automatic backup of original files to <code>uploads/codcy-image-optimizer/backup/</code></li>
<li>Skips images where WebP would be larger than the original</li>
<li>Fixes EXIF orientation automatically (Imagick)</li>
<li>Resumes from where it left off if interrupted</li>
<li>Does not alter image dimensions or crop ratio</li>
<li>No external API, no account required</li>
<li>Works with Imagick (preferred) or GD Library</li>
</ul>
What it does NOT do (intentionally):
<ul>
<li>Does not resize images</li>
<li>Does not process GIF files (may contain animation)</li>
<li>Does not delete backups automatically</li>
</ul>

Codcy Image Optimizer

Bulk convert JPEG and PNG images to WebP. No external service. Runs entirely on your server with automatic backup.

giuliopanda

Bulk images allows you to optimize images uploaded to wordpress without creating unnecessary copies of the upload folder!
Warning: the plugin overwrites images. 
Later the plugin tries to update links to images in articles and metadata, but it may happen that these need to be recreated. Other plugins that optimize images generally duplicate all images and create complex overlays to manage their systems. This plugin is designed to keep sites with the original wordpress structure, but it may require a little more work later. But I believe this work is rewarded by better final quality. 
If anything goes wrong anyway you can go back with the restore button.
<ul>
<li>You can resize all images with just one click.</li>
<li>You can convert images to webp.</li>
<li>You can optimize images by choosing quality.</li>
<li>You can change the name of the images</li>
<li>It is optimized to speed up the bulk process. 1000 images take a few minutes on a normal server.</li>
<li>You can enable the option to optimize images when uploaded to the server.</li>
<li>Allows you to decide the maximum size of the images and the quality in which they should be compressed.</li>
<li>Adds to media-library (list version) the possibility to select the images to be optimized.</li>
<li>Through graphics it allows you to monitor the status of the images on the server.</li>
<li>Ability to use specific hooks to customize optimization options.</li>
<li>You can restore and go back to the original images.</li>
<li>
You can remove the original images if you have space problems.
The GitHub repo can be found at <a href="https://github.com/giuliopanda/op-bulk-image-resizer" rel="nofollow ugc">https://github.com/giuliopanda/op-bulk-image-resizer</a>. Please use the Support tab for potential bugs, issues, or enhancement ideas.
</li>
</ul>
<h3>Credits</h3>
The Bulk image resize was started in 2021 by <a href="giuliopanda@gmail.com" rel="nofollow ugc">Giulio Pandolfelli</a>

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