Description
Petro SEO Images to WebP converts your existing JPEG and PNG attachments to WebP in bulk, then serves them on the front-end through the standard <picture> element with a full responsive srcset. The original files stay untouched on disk, so reverting is as simple as flipping a switch.
Designed to be small, dependency-free and predictable. No external services, no images uploaded anywhere, no opaque queue.
What it does
- Converts every registered image size (full + thumbnails) to
.webpnext to the original (e.g.photo.jpgphoto.jpg.webp). - Wraps
<img>tags fromwp_get_attachment_image()andthe_contentin<picture><source type="image/webp">…</picture>, preserving fullsrcsetandsizes. - Skips images automatically if a previous run failed because of filesystem permissions, so you can retry on demand without reprocessing the whole library.
- Ramps the WebP quality down (75 60 45 40) when the encoded file ends up larger than the original, so you never ship a “WebP” that is heavier than the JPEG.
- Idempotent: re-running the bulk job only touches new or updated images.
What it does NOT do
- It does not delete or modify your original JPG/PNG files.
- It does not require Imagick or a specific image library beyond what WordPress already uses (
wp_get_image_editor()). - It does not phone home, register endpoints, or load remote scripts.
Privacy
The plugin processes images locally using WordPress’s built-in image editor. No data is sent to third-party services.
Screenshots
→ Petro SEO Images to WebP — settings, bulk-conversion counters, and Convert / Revert / Retry controls.” class=”wp-image-9000001″ srcset=”https://i0.wp.com/ps.w.org/petro-seo-images-to-webp/assets/screenshot-1.png?rev=3533935&w=300 300w, https://i0.wp.com/ps.w.org/petro-seo-images-to-webp/assets/screenshot-1.png?rev=3533935&w=600 600w, https://i0.wp.com/ps.w.org/petro-seo-images-to-webp/assets/screenshot-1.png?rev=3533935&w=900 900w” sizes=”(max-width: 599px) 50vw, 33vw” width=”1836″ height=”1162″ loading=”eager” fetchpriority=”high” decoding=”async”/>Installation
- Upload the
petro-seo-images-to-webpfolder to/wp-content/plugins/, or install via the Plugins screen. - Activate the plugin through the Plugins screen.
- Go to Media Petro SEO Images to WebP.
- Click Convert all to process the existing library.
- Make sure Serve WebP is enabled to wrap front-end images in
<picture>.
FAQ
-
Will this overwrite my original images?
-
No. Originals stay on disk. The plugin writes a sibling file with the
.webpextension (e.g.photo.jpgandphoto.jpg.webp). -
How can I undo the conversion?
-
On Media Petro SEO Images to WebP, click Revert all. Every generated
.webpfile is removed and the tracking metadata is cleared. -
Some images were skipped. Why?
-
The most common cause is a write-permission issue on the uploads folder. Fix the directory permissions (e.g.
chown www-data:www-dataon Linux) and click Retry skipped to reprocess only those. -
Does it work with responsive images / srcset?
-
Yes. The
<source>element inside<picture>carries the fullsrcsetandsizes, with each URL pointing to its.webpcounterpart. URLs whose.webpis missing on disk are silently dropped from the WebPsrcsetso the browser falls back to the original<img>. -
Can I serve `.webp` files without using the “ tag?
-
If you uncheck Serve WebP the files stay on disk but the plugin will not wrap your
<img>markup. You can then serve them yourself (e.g. via Nginx Accept negotiation or a CDN rule). -
What if the WebP version ends up larger than the original?
-
The plugin retries with progressively lower quality (down to 40). If even at the lowest quality the WebP is still bigger than the source, it logs a diagnostic line and uses what it has — most browsers will still benefit from the format.
Reviews
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Contributors & Developers
“Petro SEO Images to WebP” is open source software. The following people have contributed to this plugin.
Contributors
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Interested in development?
Browse the code, check out the SVN repository, or subscribe to the development log by RSS.
Changelog
1.1.2
- Admin UI polish: ASCII-art header on Media Petro SEO Images to WebP and a discreet author credit linking to the wordpress.org profile. No functional changes — purely cosmetic.
1.1.1
- Plugin Check pass: drop empty
.gitkeepplaceholders fromincludes/andassets/(they no longer make it into the release zip). - Replace direct
is_writable()/chmod()filesystem calls withwp_is_writable(); the opportunisticchmod 0755self-heal is gone — read-only directories now surface a clean permission error instead of being silently patched. - Drop the
load_plugin_textdomain()call; wordpress.org auto-loads translations since WP 4.6. - Wrap
uninstall.phplogic in apsitw_uninstall()function so locals stay out of the file scope. - Annotate the unavoidable direct
$wpdbqueries (uninstall sweep, namespace migration, skipped-meta cleanup) andmeta_query/post__not_incalls with justifiedphpcs:ignorecomments.
1.1.0
- Rebrand to Petro SEO Images to WebP: new plugin slug
petro-seo-images-to-webp, new internal prefixPsitw_*/psitw_*(5-letter prefix per WordPress plugin guidelines). A one-time auto-migration on first load forwards every legacy storage key (siw_*andplugin_images_*) into the new namespace, so existing conversion state is preserved. - The admin page moved to Media Petro SEO Images to WebP.
1.0.4
- Rename internal class prefix and storage keys to
siw_*for unique namespacing — a one-time auto-migration runs on first load and copies legacy data forward. - Replace
@unlinkwithwp_delete_file()and addPlugin URI,Author URI,Requires at leastheaders for wordpress.org compliance. - Trim readme tags to 5, bump tested-up-to, exclude dev-only docs from the release zip.
1.0.3
- Skip attachments that fail because of filesystem permissions and offer a one-click retry flow.
- Ramp quality down when the resulting WebP is larger than the original.
- Keep the bulk loop alive when an entire batch fails by excluding failed IDs.
- Preserve full responsive
srcsetinside the generated<picture><source>.
1.0.0
- Initial public release.