The S3 Image Optimizer will optimize all your images in 1-1,000+ Amazon S3 buckets using the EWWW Image Optimizer. Since EWWW IO integrates directly with plugins like WP Offload Media, S3 IO is generally for folks who use a solution other than WP Offload Media to put their images on S3. But, if you have 20 sites sharing an S3 bucket, or have lots of buckets, and you would want to optimize them all from one place instead of 20 different sites, this is the plugin for you.
S3 IO features a web-based bulk optimization process, and a WP-CLI interface for massive buckets. S3 IO works with any S3-compatible storage service including Linode, Backblaze B2 and Digital Ocean Spaces.
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First, it is worth noting that S3 IO is "site agnostic". For example, if you have images for
http://www.example.com in your S3 bucket, you do NOT have to run S3 IO on the WordPress install for
example.com. You could install it at
test.com, or
myfuzzybunnies.com, or any site you manage. In fact, you may even create a dedicated WordPress install just for running S3 Image Optimizer, with no other plugins needed except EWWW IO and S3 IO.
Setup
Now that we have that cleared up, let's get down to business. You need 2 plugins to make this work: S3 Image Optimizer, and the
EWWW Image Optimizer. Then...
- Make sure you have configured EWWW IO with the settings you want to use.
- Setup your AWS access keys, and then enter your access keys on the S3 IO settings page and save to confirm them.
- Enter the buckets you wish to optimize in the appropriate text area. Leave it empty to have the plugin optimize all your buckets.
- You may also define constants to restrict S3 IO to a specific bucket and/or sub-folder: S3_IMAGE_OPTIMIZER_BUCKET and S3_IMAGE_OPTIMIZER_FOLDER. These override the bucket list on the settings page, and will look like this (note the lack of leading/trailing slashes on the folder setting):
define( 'S3_IMAGE_OPTIMIZER_BUCKET', 'my-amazing-bucket-name' ); define( 'S3_IMAGE_OPTIMIZER_FOLDER', 'wp-content/uploads' );
- If your IAM user does not have access to list all buckets, you will generally also need to configure the region, something like this:
define( 'S3_IMAGE_OPTIMIZER_REGION', 'eu-west-1' );
- If you are using an S3-compatible provider other than Amazon, you can define the region and endpoint constants:
define('S3_IMAGE_OPTIMIZER_REGION', 'us-west-004'); define('S3_IMAGE_OPTIMIZER_ENDPOINT', 'https://s3.us-west-004.backblazeb2.com');
- Likewise, you may need to force the usage of path-style endpoints with some providers:
define( 'S3_IMAGE_OPTIMIZER_PATH_STYLE', true );
View the full list of region names.
Usage
- Go to Media->S3 Bulk Optimizer to start optimizing your bucket(s).
- Use Media->S3 URL Optimizer to optimize specific images by their url/address.
- Use WP-CLI to optimize your buckets from the command line, especially useful for large buckets or scheduling bulk optimization:
wp-cli help s3io optimize
3.0.0
Release Date - March 4, 2026
- added: support for optimizing WebP image uploads
- added: support for WebP naming mode in EWWW Image Optimizer
- added: utility for migrating between WebP naming modes
- added: utility to remove all WebP image copies from S3
- added: option to force re-optimization of previously optimized images
- added: option to only generate WebP images
- improve: optimize by URL handles path-style URLs and 404 errors better
- changed: bulk optimizer results consolidated with image table for less memory usage and simpler navigation
- changed: AWS exception handling catches more errors and is more readable
- updated: AWS SDK to latest version
- fixed: duplicate records created when size of object in bucket changes
- fixed: uncaught PHP exception when checking ownership controls on older buckets where policy is not explicitly set
- fixed: multiple strings missing i18n
- fixed: undefined variables in exception handlers
- fixed: some strings missing i18n
- fixed: malformed AJAX responses not handled properly during bulk optimization
- security: missing some capability checks
2.6.1
Release Date - August 15, 2024
- added: override auto-detected object ownership enforcement via S3IO_OBJECT_OWNERSHIP_ENFORCED constant or s3io_object_ownership_enforced filter: set either to true to disable per-object acls
- fixed: optimize by URL incorrectly overwrites previous optimization results if multiple buckets have objects with identical paths
2.6.0
Release Date - August 1, 2024
- added: support for buckets with object ownership enforced
- added: force usage of path-style endpoint with S3_IMAGE_OPTIMIZER_PATH_STYLE
- changed: improved error handling for optimize by URL
- changed: bumped minimum WP and PHP versions
- fixed: malformed image size information in optimization table
2.5.1
Release Date - September 20, 2023
- changed: use updated WP coding standards
- changed: cleanup AWS SDK folder
2.5.0
Release Date - June 22, 2023
- added: compatibility with EWWW Image Optimizer 7+ and better future-proofing to detect compatibility errors
- updated: AWS SDK to latest version
- updated: improved PHP 8.2 compatibility, though there are still (non-critical) deprecation notices from the AWS SDK
2.4.3
Release Date - November 10, 2022
- changed: display the values of any constants defined for endpoint, region, or folder restriction
- fixed: check if the bucket list is an array before sanitizing
2.4.2
Release Date - October 5, 2022
- added: define custom endpoint for any S3-compatible storage via S3_IMAGE_OPTIMIZER_ENDPOINT
- fixed: cleanup of WebP copies using incorrect path
2.4.1
Release Date - June 21, 2022
- fixed: PHP notice when updating db records
- removed EDD_SL_Updater file/class
2.4.0
Release Date - June 17, 2021
- fixed: failure in creating s3io/ working directory silently breaks bulk tools
- fixed: sanitation for error messages was too aggressive
- fixed: listBuckets error displayed even when S3_IMAGE_OPTIMIZER_BUCKET is defined
2.3
Release Date - November 24, 2020
- fixed: conflict getting local uploads directory when S3 Uploads plugin is active
2.2
Release Date - August 13, 2020
- added: generate and upload WebP version of your images in accordance with EWWW IO settings (WebP Conversion and Force WebP)
- fixed bulk toggle-arrow styling
- additional sanitizing and escaping for better security
2.1
Release Date - March 30, 2020
- updated AWS SDK to v3, let us know if you encounter errors
- catch errors when defined region is incorrect
- added ability to remove license key (e.g. if you entered it wrong)
- rewrote bucket scanning to use AJAX in order to avoid timeouts
- fixed delay not working for WP-CLI
- display configuration errors when run from WP-CLI
- fixed S3IO_DOSPACES constant not working
- fixed scanner broken on objects with apostrophes
- fixed URL optimizer with url-encoded characters (like spaces = %20)
2.0
Release Date - August 14, 2019
- added compatibility with Digital Ocean Spaces
- lots of code cleanup and sanitation
Earlier versions
Please refer to the separate changelog.txt file.