PDEV Image Optimizer

PDEV Image Optimizer was created because I needed a small image optimization
plugin that simply did its job. I did not need a cloud dashboard, a subscription,
or a long list of advanced settings. I also did not want basic features to stop
working behind a paywall after installing the plugin.

This plugin is completely free and will remain free. There is no PRO version,
no limited free plan, no account, and no feature unlock hidden in the settings.

What does the plugin do?

PDEV Image Optimizer creates WebP or AVIF copies of images from the WordPress
Media Library. It can convert new uploads automatically and process an existing
library in small batches that can be stopped and continued later.

You only choose:

• WebP or AVIF as the output format.
• Which source formats should be converted: JPEG, PNG, GIF, or WebP where applicable.
• Conversion quality.
• Whether new uploads and images from the active theme should be processed.

The plugin also includes thumbnail scanning and regeneration, storage savings
statistics, conflict detection, optional Cloudflare support, and a detailed
system report for troubleshooting. The Settings overview explains failed checks
and links directly to the action needed to resolve each problem.

How does it work?

1. WordPress stores an image such as photo.jpg and usually creates thumbnail
   files such as photo-768x512.jpg.
2. PDEV Image Optimizer uses Imagick, or GD as a fallback, to create an optimized file next to
   each source file. The file is named photo.jpg.webp, photo.jpg.avif, or for
   example photo-768x512.jpg.webp.
3. The original image is not deleted, renamed, or replaced. WordPress content
   continues to use the original URL ending in .jpg, .png, .gif, or .webp.
4. When a browser requests that original URL, the web server checks the browser’s
   Accept header. If the browser supports the selected modern format and the
   sidecar file exists, the server returns the WebP or AVIF file instead.
5. A browser without support receives the untouched original image.

On Apache and compatible LiteSpeed servers, the plugin adds a clearly marked
PDEV Image Optimizer block to .htaccess inside the uploads directory. If
theme image optimization is enabled, it also manages a marked block in the
active theme directory. The block uses rewrite rules, sets the correct MIME
type, and adds Vary: Accept so caches know that one URL can return different
file formats.

On Nginx, WordPress cannot safely edit the server configuration. PDEV Image Optimizer therefore
shows ready-to-copy map and location blocks in System status. A server
administrator must add them to the Nginx configuration and reload Nginx.

The Settings overview includes an optional live delivery test. It creates a
temporary one-pixel source and optimized sidecar inside uploads, requests the
source URL with the appropriate Accept header, verifies the returned HTTP
status and Content-Type, and immediately removes both test files. The test runs
only when an administrator clicks Test image delivery.

Conversion and delivery are separate steps. If WebP or AVIF files exist on disk
but the server rules are missing or ignored, conversion succeeded but visitors
will still receive the original files. Check System status when this happens.

Main features

• Local WebP and AVIF conversion with Imagick or GD.
• Automatic conversion of new uploads and WordPress thumbnails.
• Restartable optimization of the existing Media Library.
• Optional optimization of supported images from the active theme.
• Thumbnail scan, missing-thumbnail repair, full regeneration, and obsolete-file cleanup.
• Per-image safety limits that skip unsafe files without stopping the whole batch.
• Storage and estimated transfer savings statistics.
• Apache/LiteSpeed .htaccess delivery and generated Nginx configuration.
• General image-plugin and rewrite-rule conflict detection.
• Optional Cloudflare Free-compatible cache integration.
• Detailed privacy-safe system report with copy and JSON export.
• Clear Settings overview with tested encoder support, server requirements, delivery status, and conflict checks.
• Actionable recovery instructions and a live HTTP test for Apache/LiteSpeed and Nginx delivery.
• Error history from the last 24 hours, limited to 50 entries.
• No external conversion service, tracking, subscription, paywall, or PRO version.

Server requirements – read before installing

The plugin needs both an image conversion library and working web-server rules.
Installing and activating the plugin cannot add missing PHP extensions or change
server configuration that your hosting provider has disabled.

Required for conversion:

• WordPress 6.4 or newer.
• PHP 8.0 or newer.
• Imagick or GD installed and enabled in PHP.
• The selected library must support the selected output format. WebP support does
  not automatically mean AVIF support.
• The WordPress uploads directory must be writable by PHP.
• Enough PHP/server memory and execution time for the size of your images.

Required for automatic delivery on Apache or LiteSpeed:

• Apache-compatible rewrite support (mod_rewrite).
• MIME and header support (mod_mime and mod_headers).
• .htaccess files must be allowed and processed for the uploads directory.
  On Apache this normally requires an appropriate AllowOverride setting.
• The uploads directory or its existing .htaccess file must be writable by PHP
  so the plugin can add its marked rules.
• If theme images are enabled, the active theme directory and its .htaccess
  file must meet the same requirements.

Required for delivery on Nginx:

• Access to the Nginx website configuration.
• Permission to add the generated map block to the http context and the
  generated location block to the correct server context.
• Permission to test and reload Nginx after changing its configuration.

If you use managed hosting and do not have access to these settings, ask the
hosting provider whether Imagick/GD supports WebP or AVIF and whether the required
Apache modules and .htaccess overrides are enabled. PDEV Image Optimizer cannot bypass server
restrictions imposed by the hosting provider.

Hosting resource protection and image limits

Image conversion can use considerably more memory than the compressed source
file suggests. To reduce timeouts, 503 responses, and account resource-limit
errors on shared hosting, PDEV Image Optimizer applies conservative limits before and during
conversion.

Default limits applied to both Imagick and GD:

• Maximum source file size: 64 MB.
• Maximum width or height: 16,384 pixels.
• Maximum total image size: 25 megapixels.

Additional GD protection:

• GD conversion uses a conservative 256 MB per-request memory budget.
• The estimate includes decoded image pixels, the source file, current PHP
  memory usage, and a reserved safety margin.
• A hosting provider or PHP configuration may impose a lower effective limit.

Additional Imagick protection:

• Memory limit: 128 MB.
• Memory-map limit: 256 MB.
• Temporary disk limit: 512 MB.
• Processing time limit: 30 seconds.
• Thread limit: 1 thread.

These are safety ceilings, not resource reservations. The server may enforce
lower limits, and increasing a PHP or plugin limit cannot bypass the hosting
account’s CPU, RAM, process, or I/O allowance.

Media Library optimization starts with one attachment per request and may use
two only after several fast batches. Slow or memory-heavy batches automatically
return to one attachment. Short pauses are added between requests, and temporary
HTTP 409, 429, 502, 503, and 504 responses use an increasing retry delay. Progress
is saved after every attachment, so a stopped job can be continued without
starting the library scan from the beginning.

One WordPress attachment can contain the original image and several thumbnail
files. Processing one attachment can therefore still convert several physical
files. Thumbnail regeneration always handles one attachment per request and
waits briefly before requesting the next one. Thumbnail scanning is lighter and
uses batches of up to five attachments.

An image that exceeds a safety limit is not converted. It is shown as a failed
item with the reason in the conversion log and error list, while the optimizer
continues with the next attachment. The original image is never removed or
modified. Developers can adjust the safeguards with WordPress filters, but doing
so should be based on the real limits of the hosting account.

External services

Cloudflare integration is optional. When configured, PDEV Image Optimizer sends the Zone ID and
API token to Cloudflare to manage its own Cache Rule and purge the selected zone.
The compatibility test requests one public Media Library image with different
Accept headers and stores only technical response information. Images are not
uploaded to Cloudflare by this plugin.

Cloudflare information: Terms and
Privacy Policy.

Support

Support is provided only through the official support forum for this plugin on
WordPress.org: PDEV Image Optimizer support forum.

Support is not provided by email, through the author’s website, Ko-fi, social
media, private messages, or any other channel. Please use the WordPress.org forum
so questions and solutions remain public and useful to other users.

Before opening a topic, check Tools > Image Optimizer > System status,
then copy the report or export its JSON file and include the relevant details in
your forum post. The report is designed to omit URLs, credentials, personal data,
full server paths, and media content.