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)
  • Faster load times for blog pages
  • Support for WooCommerce
  • WordPress multisite-support
  • Bulk optimization (optimize existing images)


  • 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 >=5.6
  • WordPress >=4.6
  • 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


Augustus 7, 2019
The 100kb limit of the free version is very limiting and mostly serves like a demo. My disappointment was that even though i had the premium version and i optimized the images, google pagespeed still had the message that my images could be smaller.
Januarie 19, 2019
Pourquoi perdre du temps quand un outil peut vous en faire gagner… Si vous avez des images trop lourdes qui peuvent ralentir votre site, c’est l’outil idéal.
Desember 27, 2018
A simple, fast and easy to use plugin that has great features to offer. I’ve purchased a key for the Pro version a few days ago and converted all my pictures to webP. My blog is faster than ever. If you care about your site’s speed, stop what you’re doing and purchase a key!
November 13, 2018 2 replies
ein gutes Tool, erfunden von einem der Besten -> Sergej Müller… doch nun macht das absolut keinen Sinn mehr. Warum? Hatte man mal eine HQ Lizenz und möchte diese nicht verlängern, so versagt das Plugin anschließend seinen Dienst komplett und bedient nicht mal mehr die “freien Features”.
Read all 68 reviews

Contributors & Developers

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Interested in development?

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



  • WordPress 6.1 compatibility


  • WordPress 6.0 compatibility


  • Fix bulk image optimization (#13 @tg247)


  • Skip missing files
  • Added wpcli command for bulk optimization
  • Added option to append instead of replace file extension for webp files


  • Unsupported image types are now gracefully skipped
  • Renamed setting names and greyed out inapplicable settings to avoid confusion
  • Increased size limit for Optimus HQ to 10MB
  • Licences can now easily be extended
  • Optimize images uploaded through the REST API


  • Formatting updates


  • 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


  • Erhöhung des Limits für PNG-Dateien auf 512 KB (Optimus HQ)


  • Umstellung des Plugins auf die neue Optimus API (cURL only)


  • Kompatibilität zu WooCommerce
  • Einführung von Optimus HQ PRO


  • Anzeige der in WordPress registrierten Bildgrößen (Thumbnails)


  • 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


  • Optimierungen am Plugin-Rechtemanagement
  • Überarbeitung der Plugin-Hinweise


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


  • Anzeige des Optimus HQ Ablaufdatums
  • Admin-Hinweis bei abgelaufener Optimus HQ Lizenz


  • 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


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


  • Unterstützung für WordPress Apps und Windows Live Writer


  • Option: Bild-Metadaten nicht entfernen


  • Interne Umstellung auf Mime-Type
  • Code-Optimierungen


  • Umstellung auf Freemium Modell
  • Plugin Website: optimus.io


  • 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