Optimus – WordPress Image Optimizer


WordPress Image Optimizer

Optimus reduces the file size of uploaded media files automatically. Depending on the image and format, reductions in size of up to 70% are possible. Several kilobytes can be saved per image—these savings contribute positively to the performance of the blog website. What’s most impressive about the compression technology: the quality of the images is maintained.

There are three different versions of Optimus:

  1. Optimus (Free) as base version with limitations (e.g. max of 100kb)
  2. Optimus HQ (Premium) with expanded functionality for personal projects
  3. Optimus HQ PRO (Premium) as professional solution for customer websites

More details about the features and the pricing model on optimus.io

How does it work?

During the uploading process of images to the media library, the Optimus plugin simultaneously sends the images to the Optimus server, where the incoming material is processed and sent back in optimized form. Afterwards, the Optimus plugin saves the image version with a reduced file size in the media library.

The optimization of images – including thumbnails – is conducted in the background and outside of the view of the user. The image compression gains per file are displayed by Optimus within the media library in form of a percentage value, see screenshot.

Superfluous information that is saved by image processing programs and is not even necessary for displaying the image is extracted from image files. This way, the quality of the graphics remains intact while the image size can be reduced significantly. If you wish, Optimus keeps all author, EXIF and copyright information contained within the photos — the compressional gains will be correspondingly lower.

Optimus supports the conversion of images to the new WebP image format.

It is recommended to use the WordPress Cache Enabler plugin to integrate the converted WebP images.


  • Progressive JPEGs
  • Reduction of file size during the upload
  • Optimization of all preview images of a photo
  • No adjustments to code necessary
  • Optional: no removal of EXIF and IPTC metadata
  • Optional: HTTPS connection for the image transfer (Optimus HQ)
  • Optional: conversion to the WebP image format (Optimus HQ)
  • Optional: Disable automatic optimization during upload process
  • Optimized for WordPress Mobile Apps and Windows Live Writer
  • More advantageous PageSpeed, influencing the Ranking Factor
  • Faster load times for blog pages
  • Support for WooCommerce
  • WordPress multisite-support
  • Bulk optimization (optimize existing images)
  • Optimize images generated by WP Retina 2x (incl. conversion to WebP)


  • After the image optimization and transfer process, the Optimus server immediately deletes all the temporarily stored files. No files are stored!
  • The Optimus servers are located in Germany.


  • Photos should always be saved as JPEGs rather than PNGs. The PNG format works well for illustrations, JPEG on the other hand is the right choice for photographs. Another reason: the size reduction always works more quickly for JPEGs.
  • Your images have been optimized using Desktop tools such as ImageOptim (Mac) or PNGGauntlet (Win) before you upload them? Optimus has the significant benefit of also minimizing the thumbnails (=preview images) created by WordPress. After all, themes almost always integrate thumbnails rather than original images.

System Requirements

  • PHP >=5.2.4
  • WordPress >=3.8
  • Allow outbound connections

Storage Utilization

  • Backend: ~ 0,19 MB
  • Frontend: ~ 0,01 MB




  • Display of the compression rate and how many images have been optimized (circle)
  • Before and after: Original image incl. thumbnails without compression (above) and below with Optimus compressed/optimized


I’m excited

I’m quiet excited about this tool and about the service of the developer as well.

Useless nonsense

The authors claim that the plug-in reduces photos. Great, let’s check it out.

1) Uploading photos to the site.
2) In the admin panel there is a “compression”:


3) Now I will check whether this is so. I save the photo from the site (“compressed” plugin) and compare its size with the original:


It’s a miracle! The size of the “compressed” is larger than the original!

I repeated the experiment with 20 other photos from the site. In all cases, “compression” did not work, in four cases the size of the “compressed” photo was larger than the original.

Conclusion: plug-in – useless nonsense, advertising of authors and their service. I do not recommend it. Better optimize photos manually or with the online compression services.

I love Optimus Image Optimizer!

It goes without saying that there are tons of plugins out there, but Optimus Image Optimizer is most definitely different in a really good way. For starters, it fixes a very crucial issue: page load speed (among other things). Coming from an SEO background, I have to fix my clients’ sites in terms of making them more lightweight. And that’s exactly when Optimus Image Optimizer comes into play and it does the trick in a super-efficient manner.

I especially love the retrospective feature. That means not only your new images get optimized (images you used after installing the plugin) but also the rest of the images that are on your site get optimized as well! Huge kudos for making that possible.

As a matter of fact, you can see everything I think about this awesome plugin in this post:

[link redacted]

Long story short, I really recommend using it.

Easy and Effective!

I use Optimus on all of my websites. It’s extremely straightforward to use and comes with a few features that make the plugin stand out such as: WebP support (this is a big one), bulk optimization, and the option to choose whether or not to optimize upon upload.

+30% Performance!

Installing the plugin is very easy and self explaining. Generating webp files on the fly is a really cool option! I also use the API (Optimus HQ) to automatically optimize all pictures on my community website. Overall, I got 30% peformance increase due to this plugin.. which is more than ever expected! Thanks!

Read all 49 reviews

Contributors & Developers

“Optimus – WordPress Image Optimizer” is open source software. The following people have contributed to this plugin.




  • Improved the handling of 204 errors
  • Removed language files


  • Improved the bulk optimizer


  • Added support for WP Retina 2x


  • Optimization to avoid conflicts with other plugins or themes


  • Fixed static function warning in PHP 5.6


  • Increased timeout value to 180 seconds


  • Allow to generate WebP images on already optimzed images (bulk optimizer)


  • Improves bulk optimization error handling


  • Added PNG in the free version and the manual optimization setting


  • Bug fixing and activation update


  • Bulk optimization feature



  • Neue Option: Keine Optimierung der Originalbilder
  • Korrektur: Löschung der WebP-Bilder im AJAX-Modus
  • Ausführlich auf Google+






  • Anpassung für WordPress 3.9: Sicherstellung der Bildoptimierung im WordPress-Editor


  • Überarbeitung der Kommunikation via cURL
  • Implementierung von HTTPS (Optimus HQ)
  • Zusätzliche Checks beim Versand und Empfang der Daten
  • Vereinfachung der Feedback-Ausgabe in grünen Kreisen
  • Kein Abgleich der Davor-Danach-Bildgrößen für 204-Header
  • Connection-Timeout auf 10 Sekunden
  • Tiefgehende Code-Revision



  • Optimus HQ: Umbau der Lizenzverifizierung wegen einem Bug im W3 Total Cache Plugin
  • Ausbau der Schnittstelle für binäre Datenübertragung



  • Christmas-Edition (Code- & Performance-Optimierungen)


  • Optimiert für WordPress 3.8


  • Optimus HQ: Eingabe eines neuen Lizenzschlüssels möglich
  • Selbstprüfung auf Erreichbarkeit der Upload-Bilder (Zugriffsschutz, etc.)
  • Performance-Optimierungen
  • Ausführlich auf Google+


  • Optimus HQ: Erhöhung des Limits für PNGs auf 200 KB
  • Optimus HQ: Konvertierung der Bilder ins WebP-Format




  • Interne Umstellung auf Mime-Type
  • Code-Optimierungen



  • Code-Freeze
  • Vervollständigung der FAQ
  • Filter für lokale Installationen


  • Support für PNGs


  • Beschränkung auf JPEGs (da fast keine PNG/GIF-Nutzung)
  • Menge der optimierten Thumbnails als Diagramm
  • Überarbeitung diverser Code-Fragmente


  • Verbesserte Fehlerausgabe an den Nutzer


  • Erweiterung der FAQ
  • Unterstützung für WordPress 3.5
  • Erhöhung des max. Limits auf 300 KB


  • Zusatzabfrage für (korrupte) Bild-URLs
  • Weiterer Screenshot


  • Diverse Code-Optimierungen
  • Reduzierung der Max-Größe


  • Unterstützung für PHP 5.2.4


  • Überarbeitung der GUI


  • Init release