Title: SEV WebP Migrator for W3TC Author: Heinrich Franz Published: July 24, 2026 Last modified: July 24, 2026 --- Search plugins ![](https://ps.w.org/sev-webp-migrator-for-w3tc/assets/icon.svg?rev=3621559) # SEV WebP Migrator for W3TC By [Heinrich Franz](https://profiles.wordpress.org/hfranz/) [Download](https://downloads.wordpress.org/plugin/sev-webp-migrator-for-w3tc.2.0.1.zip) * [Details](https://wordpress.org/plugins/sev-webp-migrator-for-w3tc/#description) * [Reviews](https://wordpress.org/plugins/sev-webp-migrator-for-w3tc/#reviews) * [Installation](https://wordpress.org/plugins/sev-webp-migrator-for-w3tc/#installation) * [Development](https://wordpress.org/plugins/sev-webp-migrator-for-w3tc/#developers) [Support](https://wordpress.org/support/plugin/sev-webp-migrator-for-w3tc/) ## Description SEV WebP Migrator for W3TC is a companion plugin for [W3 Total Cache](https://wordpress.org/plugins/w3-total-cache/) that finishes the job once W3TC ImageService has converted an image to WebP. No changes to `.htaccess`, `mod_rewrite`, or web server configuration are required. Instead, it writes the replacement back into the database **once**, unlike a runtime content filter that swaps URLs on every request: as soon as W3TC marks an attachment as converted, every occurrence of that image’s URL in `post_content` across the whole site is permanently replaced, from its original extension (jpg/jpeg/png/gif) to `.webp`. The attachment’s own record (attached file, metadata, mime type) is updated to match, so the Media Library and REST API stay consistent too. Optionally, once an image has been fully replaced, the plugin can delete the now- unused original source files from disk to reclaim storage space. This is an independent, unofficial add-on and is not affiliated with, endorsed by, or sponsored by BoldGrid / W3 EDGE, the makers of W3 Total Cache. “W3 Total Cache” is a trademark of its respective owner and is used here only to describe compatibility. **Features** * Listens for W3TC ImageService conversions and reacts automatically. * Replaces every reference to the converted image (full size and all intermediate sizes) in `post_content`, across all posts. * Updates the attachment’s own file reference, metadata, and mime type to match. * Optional: deletes the original source files after a successful replacement. * A source file is only ever deleted once its `.webp` counterpart has been confirmed to exist on disk. * Manual “process now” tool in **Settings WebP Migrator for W3TC** for images that were converted before this plugin was active. **How it works** 1. W3 Total Cache ImageService converts an image and marks the attachment’s `w3tc_imageservice` post meta as `converted`. 2. This plugin detects that meta change and looks up every file W3TC generated for the attachment (full size and each registered thumbnail size). 3. It scans `post_content` across all posts for the old URLs and replaces them with the `.webp` versions directly in the database. 4. The attachment’s own `_wp_attached_file`, `_wp_attachment_metadata`, and `post_mime_type` are updated to point at the `.webp` files. 5. If enabled in the settings, the original files (jpg/jpeg/png/gif) are deleted from disk. **Requirements** * W3 Total Cache must be installed and active. * Images must be converted using **Media W3TC Image Service**; this plugin does not perform any conversion itself. **Limitations** This plugin **does not convert images** to WebP — conversion is handled entirely by W3 Total Cache ImageService. It only reacts once W3TC reports an image as converted. This plugin only handles **WebP**. AVIF is not supported: W3 Total Cache only offers AVIF conversion in its paid Pro version, and this plugin’s free-tier ImageService integration only ever sees WebP conversions. Deleting source images is permanent and cannot be undone by this plugin. Keep backups before enabling automatic deletion. ## Installation 1. Upload the `sev-webp-migrator-for-w3tc` folder to the `/wp-content/plugins/` directory. 2. Activate the plugin through the **Plugins** menu in WordPress. 3. Ensure W3 Total Cache is installed and active. 4. Optionally enable “Delete source images” under **Settings WebP Migrator for W3TC**. 5. For images W3TC already converted before activation, use the “process now” tool on the same settings page. ## FAQ ### Does this plugin convert images to WebP? No. Image conversion is handled entirely by W3 Total Cache ImageService. This plugin only replaces already-converted images’ URLs, permanently, in post content and in the attachment’s own record. ### How is this different from “SEV Rewrite-Free WebP for W3TC”? The rewrite-free plugin swaps URLs on the fly for browsers that support WebP, leaving the original content and files untouched. This plugin instead permanently replaces the stored content and, optionally, removes the original files — useful once you no longer need to serve the original format to any visitor. ### Is deleting source images safe? A source file is only deleted once its `.webp` counterpart has been confirmed to exist on disk, after post content and the attachment record have already been updated. Deletion is still permanent and disabled by default — enable it deliberately, and keep backups. ### Does it work with WordPress Multisite installations? Yes. Each site processes its own W3 Total Cache ImageService conversions independently. ## Reviews There are no reviews for this plugin. ## Contributors & Developers “SEV WebP Migrator for W3TC” is open source software. The following people have contributed to this plugin. Contributors * [ Heinrich Franz ](https://profiles.wordpress.org/hfranz/) “SEV WebP Migrator for W3TC” has been translated into 1 locale. Thank you to [the translators](https://translate.wordpress.org/projects/wp-plugins/sev-webp-migrator-for-w3tc/contributors) for their contributions. [Translate “SEV WebP Migrator for W3TC” into your language.](https://translate.wordpress.org/projects/wp-plugins/sev-webp-migrator-for-w3tc) ### Interested in development? [Browse the code](https://plugins.trac.wordpress.org/browser/sev-webp-migrator-for-w3tc/), check out the [SVN repository](https://plugins.svn.wordpress.org/sev-webp-migrator-for-w3tc/), or subscribe to the [development log](https://plugins.trac.wordpress.org/log/sev-webp-migrator-for-w3tc/) by [RSS](https://plugins.trac.wordpress.org/log/sev-webp-migrator-for-w3tc/?limit=100&mode=stop_on_copy&format=rss). ## Changelog #### 2.0.1 * Tested up to WordPress 7.1 and W3 Total Cache 2.10.2. #### 2.0.0 * Improved compatibility with W3 Total Cache ImageService image conversions. * Added an option to automatically delete original images after successful conversion. * Various code improvements. #### 1.0.0 * Initial release. ## Meta * Version **2.0.1** * Last updated **1 day ago** * Active installations **Fewer than 10** * WordPress version ** 6.0 or higher ** * Tested up to **7.1** * PHP version ** 8.0 or higher ** * Languages * [English (US)](https://wordpress.org/plugins/sev-webp-migrator-for-w3tc/) and [German](https://de.wordpress.org/plugins/sev-webp-migrator-for-w3tc/). * [Translate into your language](https://translate.wordpress.org/projects/wp-plugins/sev-webp-migrator-for-w3tc) * Tags * [images](https://wordpress.org/plugins/tags/images/)[optimization](https://wordpress.org/plugins/tags/optimization/) [performance](https://wordpress.org/plugins/tags/performance/)[W3 Total Cache](https://wordpress.org/plugins/tags/w3-total-cache/) [webp](https://wordpress.org/plugins/tags/webp/) * [Advanced View](https://wordpress.org/plugins/sev-webp-migrator-for-w3tc/advanced/) ## Ratings No reviews have been submitted yet. [Your review](https://wordpress.org/support/plugin/sev-webp-migrator-for-w3tc/reviews/#new-post) [See all reviews](https://wordpress.org/support/plugin/sev-webp-migrator-for-w3tc/reviews/) ## Contributors * [ Heinrich Franz ](https://profiles.wordpress.org/hfranz/) ## Support Got something to say? Need help? [View support forum](https://wordpress.org/support/plugin/sev-webp-migrator-for-w3tc/)