README

A WordPress must-use plugin that stops core from generating intermediate image sizes and instead serves every size on the fly from an AWS Serverless Image Handler (or any Thumbor-compatible CDN).

It is URL layer only: no AWS credentials, no SDK. It rewrites the image URLs WordPress emits and disables thumbnail generation, so it pairs with any storage backend (your own S3 offload, WP Offload Media, Humanmade S3 Uploads, or a manual sync).

📖 Full write-up: Make WordPress do less: offloading media to S3 and the edge

The problem

On every upload WordPress generates a stack of resized copies (thumbnail, medium, medium_large, large, 1536, 2048, plus theme sizes) and stores them all. Most are never requested. If a CDN can produce any size on demand, pre-generating a fixed menu of sizes is wasted CPU at upload time and wasted storage forever.

What it does

• Turns off intermediate sizes. No more thumbnail generation on upload.
• Rewrites image URLs to the edge. wp_get_attachment_image_src (featured images, blocks, the_post_thumbnail), the responsive srcset, and inline content images (WP 6.0+) all point at the Image Handler, with the requested dimensions encoded in the URL.
• Synthesizes srcset and sizes. Because there are no recorded sub-sizes to build responsive markup from, the plugin generates a width set (never wider than the original) pointing at the edge, so responsive images keep working.
• Stays out of the way. Non-raster files (SVG, etc.) are skipped, and with no base URL configured the plugin is a no-op.

Installation

This is a must-use plugin, so it loads before output is rendered and cannot be deactivated by accident.

Manual

mkdir -p wp-content/mu-plugins
cp wp-edge-images.php wp-content/mu-plugins/

Composer

composer require mantekio/wp-edge-images

Composer installs it as a wordpress-muplugin via composer/installers, which has two consequences worth knowing:

• Allow the installer plugin. On a fresh project Composer blocks composer/installers until you permit it. Add to your root composer.json (most WordPress-Composer stacks already have it):

  { "config": { "allow-plugins": { "composer/installers": true } } }

• Make sure it loads. It installs into wp-content/mu-plugins/wp-edge-images/ (a subfolder). Vanilla WordPress only auto-loads *.php placed directly in mu-plugins/, not in subfolders, so either use a mu-plugins autoloader (Bedrock and similar stacks ship one) or use the Manual method above.

Configuration

Point the plugin at your Image Handler / CDN base. Everything else has sensible defaults and is filterable.

// Required: the Serverless Image Handler / Thumbor CDN base.
define( 'WP_EDGE_IMAGES_BASE', 'https://images.example.com' );

The default URL form is Thumbor style, which the AWS Serverless Image Handler understands:

https://images.example.com/fit-in/800x0/filters:format(auto):quality(80)/2025/07/20250727-1753632511534.jpg

format(auto) lets the handler return AVIF or WebP by the browser's Accept header from a single master.

How it works

The full architecture (two-copy S3 storage, on-the-fly derivatives, clean generated keys, browser-direct video uploads, and platform-independent playback) is in the write-up:

→ Make WordPress do less: offloading media to S3 and the edge

License

GPL-2.0-or-later: same as WordPress.

Built and maintained by ManTek Technologies: WordPress + AWS at scale, for media-grade publishing.