: the only free Image Optimizer & compress plugin

Description Image Optimizer allow to use free Image optimization based on API. provides image size reduction based on several advanced algorithms. The API accept JPG, PNG and GIF files up to 5MB.

This plugin includes a bulk operation to optimize all your pictures in 2 clicks ! Change your image optimization level to fit your needs !
This service is used by more than **400,000php websites on different CMS (WordPress, Drupal, Joomla, Magento, Prestashop…).

The plugin includes an option to exclude some pictures of the optimizer.

Since Aug. 2016, allows to optimize pictures up to 5MB, for free !


  • The simple interface


  1. Upload resmushit-image-optimizer to the /wp-content/plugins/ directory.
  2. Activate the plugin through the ‘Plugins’ menu in WordPress.
  3. All your new pictures will be automatically optimized !


How great is ?

Since we’ve optimized more than 15,000,000,000 pictures, we’ve risen new skills. Our service is still in development to bring you new crazy functionalities.

What about WebP and next generation image formats ?

We’re working on a new offer to bring you the best of these new features. Please be patient, it will come soon 🙂

Is there an “Optimize on upload” feature ?

Absolutely, this feature is enabled for all new pictures to be added, and can be disabled on will.

Is there a CRON feature ?

Yes, for big (and even for small) media Libraries, you can optimize your pictures using Cronjobs.

Can I choose an optimisation level ?

Yes, by default the optimization level is set at 92. But you can optimize more your pictures by reducing this optimization level.

Can I go back to my original pictures ?

Yes, by excluding/reverting this asset you’ll have your original image available.

Is it possible to exclude some pictures from the optimizer ?

Yes, since version 0.1.2, you can easily exclude an asset from the optimizer.

Have I a risk to lose my existing pictures ?

Nope ! Image Optimizer creates a copy of the original pictures, and will perform optimizations only on copies.

Is it free ?

Yes ! Absolutely free, the only restriction is to send images below 5MB.


Juli 27, 2023
Very nice plugin for optimization!I propose to make support for converting images to WebP format.It would also be nice to increase the speed of image processing.Thank you!
Agustus 29, 2022
Unfortunately I had a lot of problems with Even running it on a fairly new and clean website with few other plugins. 1. constantly had problems connecting to a server. 2. When I tried uploading an image I sometimes had to wait for minutes before smushed it. I don't know whether it had anything to do with the server connection issue. 3. When I tried to recreate all images it broke the site after which I had to install the site from a backup. The fact that there is an admin notice saying to backup the whole site before doing that only means that this is a common issue. All in all I had very bad experience with the plugin and I don't recommend it to anyone.
Juli 23, 2022
It is free but I would recommend using a different one. Impossible to restore images No support No documentation on how to restore. Would look somewhere else
Read all 131 reviews

Contributors & Developers

“ : the only free Image Optimizer & compress plugin” is open source software. The following people have contributed to this plugin.


“ : the only free Image Optimizer & compress plugin” has been translated into 10 locales. Thank you to the translators for their contributions.

Translate “ : the only free Image Optimizer & compress plugin” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.



  • Patreon new message


  • Patreon display message 🙁


  • Missing image


  • Partnership with Shortpixel
  • fix crash bug when uploading non Image document in library (while log enabled)


  • Compatibility with WP 6.1.0
  • Compatible with PHP 8.1.X
  • Fixed issue on Undefined array key “file” in …/resmushit.php on line 114


  • Incorrect library imported (fix PHP Fatal error: Uncaught Error: Undefined constant “SECURE_AUTH_COOKIE” in /wp-includes/pluggable.php:923)


  • Security fixes : CSRF protection for Ajax Calls


  • Security fixes : protection in a WP’s way


  • Security fixes : prevent XSS breachs


  • Avoid SSL verifications if certificate of remote endpoints fails.
  • Security fixes : escape POST, and admin user check for AJAX requests


  • Compatibility with WP 6.0.1
  • Security fix issues (
    • force int to ID in some SQL requests
    • check that user is connected as admin/contributor for AJAX actions
    • Message to indicate that there’s no collection of data in contacting remote feed service


  • Compatibility with PHP8+WP 5.8.2


  • Official support of WP-CLI
  • Fix cron context optimization


  • New option to restore all original pictures


  • Fix : Default value assignment
  • Test on WP 5.7.1


  • Fix : Optimize button not working when creating a new post
  • Fix : Default value of variables incorrectly initialized
  • Test on WP 5.5.1


  • hotfix : deprecated function used


  • Fix : OWASP & Security fix


  • Fix : Fix warning in variable not set (metadata)
  • Fix : Add an extension uppercase check


  • Fix : CSS+JS load on every admin page, now restricted to pages & medias
  • Fix : Links verification format for admin menu


  • Fix : cron multiple run issue.


  • New header image, new WP description for plugin page.


  • Issue in version number


  • Fix double cron launch. Timeout added
  • Fix “Reduce by 0 (0 saved)” message if statistics are disabled
  • Return error if attachment file not found on disk


  • Fix variable check (generate notice)


  • Fix log write (permission issue)
  • Fix “Reduce by 0 (0 saved)” error. Optimize single attachment while “Optimize on upload” is disabled


  • Add Backup deletion option
  • Add script to delete old backups
  • Changed JS inclusion


  • Add Preserve Exif Feature


  • Fix issue on SQL request for table prefix different from ‘wp_’


  • Version number issue


  • Fix settings automatically reinitialized.


  • Complete French translation
  • Plugin translation fix


  • Add CRON feature
  • Code refactoring
  • Fix issue for big Media library, with a limitation while fetching attachments
  • Fix log path issues


  • Add Settings link to Plugin page
  • Limit options to image attachments only
  • Fix RESMUSHIT_QLTY is not defined


  • Fix on attachment metadata incorrectly returned (will fix issues with other media libraries)


  • WordPress 5.0 compatibility


  • Fix PHP errors with PHP 7.2
  • Code refacto


  • Fix JS on “Optimize” button for a single picture
  • Provide a new “Force Optimization” for a single picture


  • Avoid filesize () : stat failed errors if a picture file is missing
  • Log check file permissions
  • Check extensions on upload (avoid using API if it’s not a picture)
  • Increase API Timeout for big pictures (10 secs)


  • Fix bug (non-working optimization) on bulk upload when “Optimize on upload” isn’t selected
  • New header banner for 4 billionth images optimized


  • Add correction for allow_url_fopen support
  • News feed loaded from a SSL URL


  • Log rotate if file too big


  • Tested up to WordPress 4.9.5
  • New contributor (resmushit)
  • Translation completion


  • Tested up to WordPress 4.9.1
  • New header banner for 3 billionth images optimized 🙂


  • Tested up to WordPress 4.8.1


  • New header banner for 2 billionth images optimized 🙂


  • Slovak translation fix


  • Slovak translation fix


  • Italian translation added (thanks to Cristian R.)
  • Description minor correction


  • Slovak translation added (thanks to Martin S.)


  • Bug fix when images uploaded > 5MB
  • List of files above 5MB
  • Translation minor corrections


  • Error management if webservice not reachable
  • Filesize limitation increased from 2MB to 5MB


  • CSS Fixes


  • Translation correction
  • News feed images correction


  • Delete also original file when deleting an attachment
  • Exclusion of an attachment of the optimization (checkboxes)
  • Adding french translation
  • Code optimizations
  • 4.6.x check
  • Minor bugs corrections


  • Optimize on upload
  • Statistics
  • Log services
  • Interface rebuild
  • News feed from


  • plugin base
  • bulk optimizer