WP Plugin Optimus
Test report

Optimus - WordPress Image Optimizer

Optimus is a WordPress plugin developed by KeyCDN and has been published since 2012-10-05. It now counts over 30 000+ active installations. The plugin’s main goal is to automatically reduce the file size of uploaded media, which significantly improves site performance without noticeably affecting image quality. One of Optimus’s unique selling points is the ability to compress images by up to 70% - this happens completely in the background, which sets it apart from other solutions that often require more user interaction. Optimus is aimed specifically at bloggers, web developers and website owners who want to optimize their site for both loading times and user experience. With an average rating of 4.2 out of 5 stars from 68 reviews in the official WordPress Plugin Directory, it’s clear that it’s a well-regarded solution in the WordPress community. The specific features of the plugin are detailed below.

"Optimus not only saves a lot of time but also works absolutely efficiently."

Features - Comprehensive image optimization capabilities

The WordPress plugin Optimus offers a variety of features focused on reducing image file sizes. In addition to the already mentioned automatic file size reduction and seamless background optimization, there are other notable functions. An additional advantage is support for bulk optimization, which allows you to efficiently optimize not only new but also already uploaded images on the site. This enables a comprehensive performance boost without sacrificing convenience and usability. With this feature, Optimus stands out from many other image optimization plugins in the WordPress community.

"Bulk optimization is a feature many other plugins don’t offer."

Free Features - Extensive capabilities in the free version

• File size reduction during upload - Automatic reduction of file size for uploaded media.
• Optimization of all preview images of a photo - Improved image quality while reducing file size.
• No code adjustments necessary - Easy integration without programming knowledge.
• Optional retention of EXIF and IPTC metadata - Option to keep metadata in images.
• Faster loading times for blog pages - Improved website performance.
• Support for WooCommerce - Compatibility with WooCommerce for online stores.
• WordPress Multisite support - Works in multisite environments.
• Bulk optimization - Ability to optimize existing images.

Pro Features - Advanced features for professional users

• Optimus HQ - Extended functionality for personal projects.
• Optimus HQ PRO - Professional solution for client websites.
• Optional HTTPS connection for image transfer - Secure image transfer (only Optimus HQ).
• Optional conversion to the WebP image format - Support for the modern WebP format (only Optimus HQ).

"The ability to create WebP images is a big advantage for the site's loading speed."

Licensing & value for money - Free base version and fair premium options

Optimus offers a free base version that provides basic image optimization features but is limited to files under 100 KB. This limitation makes the free access less attractive for some users, for example for larger images. For extended features, the paid versions Optimus HQ and Optimus HQ PRO are available. These premium versions allow you to exploit the full capabilities of the plugin, such as WebP support and removing size limits. Users often rate the pricing positively; the annual fee is seen as fair and balanced, especially considering the unlimited image optimization it offers.

"I love the pricing. Sometimes you can buy it for $19 and use it for unlimited images."

Technical details - Insight into how the plugin works

The Optimus plugin operates through tightly integrated server communication, where image optimization takes place on an external KeyCDN service. When uploading an image, the plugin sends the file directly to the Optimus server. There the image is losslessly compressed by discarding unnecessary metadata that increases file size but is rarely needed. The optimized images are returned in real time to the WordPress media library, making the process seamless and transparent for the user. Another technical feature is the ability to generate WebP formats, which can significantly improve webpage loading times. By using caching mechanisms and the plugin’s minimal memory footprint (~0.19 MB backend and ~0.01 MB frontend), the web server performance is barely impacted, even when deployed on WordPress Multisite platforms.

System requirements - Requirements and compatibility

Optimus is designed to offer broad compatibility with various WordPress configurations. The minimum requirements for the plugin include a PHP version 5.6 or higher and a WordPress version 4.6 or higher. It has been extensively tested up to WordPress version 4.6, ensuring its reliability on those versions. The current plugin version 1.6.3 and the last update in 2025-09 were released. These continuous updates and high compatibility standards ensure reliable integration of Optimus in different hosting environments, which is also confirmed by user reviews.

"Optimus runs reliably on my multilingual multisite installation without causing complications."

Quality - Focus on efficiency and image quality

Optimus stands out for its high efficiency in image compression without noticeably compromising image quality. Users report massive reductions in image sizes, which can lead to better site performance while preserving the visual integrity of images. Notably, Optimus can compress without perceptible quality loss, setting it apart from many other image optimization plugins on the market. This advantage is enabled by the integrated technology that achieves reductions of up to 70%, a result well above average. The plugin's quality is also reflected in user satisfaction, with many appreciating its stable operation and reliability.

“This tool helps deliver massively smaller images while keeping quality high.”

Support - Experiences with the plugin support

The support for the WordPress plugin Optimus appears mixed in user reviews. Positively highlighted are the fast response times and effective assistance with issues. Users report prompt and helpful replies to their inquiries, indicating good and reliable support. The quick resolution of problems in particular sets Optimus apart from other plugins. On the other hand, there are critical voices describing the support as unfriendly and unhelpful. In some cases, no response to support requests was received, leading to frustration.

For support inquiries, a support page in the WP Plugin Directory and a developer support URL are available. Experiences with support therefore vary, which potential users should consider when making their decision.

"Support is great with quick responses and problem resolution."

Rating - Average rating and user opinions

Optimus achieves an average rating of 4.2 out of 5 stars based on 68 reviews in the official WordPress Plugin Directory. This suggests the plugin is positively received by the majority of users. Many users value the efficiency and usability that Optimus offers, especially in image compression without quality loss. However, there are also some critical voices regarding the plugin’s functionality and the value for money of the Pro version.

Some users praise Optimus for its practical features:

“This plugin is really handy. After installation and uploading, all images are already optimized.”

Others are less satisfied, particularly with the paid version:

“For this price it’s the worst purchase ever; even most free plugins had more options and did a better job.”

Still, many are very satisfied with Optimus and highlight its benefits:

"Optimus not only saves a lot of time but also works absolutely efficiently."

Criticism - Issues, vulnerabilities and suggestions for improvement

Although Optimus is praised by many users for efficiency and simplicity, there are also some criticisms evident in the reviews. A major drawback is the free version’s limit to image sizes of up to 100 KB. This restriction makes the plugin unusable for many users who rely on larger media files and leads to dissatisfaction. Furthermore, the functionality of the paid version is described as insufficient, especially compared to other often free plugins. Users complain that the paid version lacks features that are standard in competing products.

Another criticism is the slowed processing times when many image sizes are generated. This leads to increased processing time for websites and restricts usability as a result. Regarding security vulnerabilities or serious bugs, no specific reports were found in public information, indicating the plugin appears solid in terms of privacy and security.

Despite error-free operation, the lack of support for images uploaded via the WordPress API is also seen as a disadvantage. This incompatibility restricts users who frequently work with such images and is viewed as further potential for improvement.

“In the standard version only photos that are not larger than 100 kb can be optimized - totally pointless, unfortunately!”

Conclusion - Summary of strengths and weaknesses

The WordPress plugin Optimus from KeyCDN stands out for its efficient image compression, which enables noticeable improvements in website performance. Seamless integration into the workflow and the ability for bulk optimization are significant advantages over other plugins. While the free basic version offers core features, its 100 KB limit may make it less attractive to many. The paid versions, on the other hand, offer more extensive options, such as support for WebP formats and removal of size restrictions.

Another plus is the technically refined processes on external servers that keep the website’s server load low while still achieving high efficiency. Nevertheless, support receives some critical feedback regarding usability and functionality. The pricing of the paid versions is generally perceived as reasonable, but not all users are convinced by the provided features. Optimus proves to be a strong solution for specific requirements, but the limitations of the free version and consideration of other options should be taken into account.