Compression Plugin Review: Smush Pro vs Kraken vs EWWW

Compression Plugin Review: Smush Pro vs Kraken vs EWWW

For years now, WP Smush has been the most popular free image compression plugin for WordPress with more than 200,000 active installs.

It’s ideal for people with minimal smushing needs, but since it’s limited to 1MB it’s not so great for those who have some serious smushing to do, such as photographers.

So we developed WP Smush Pro to meet the needs of serious smushers.

Since WP Smush Pro was launched we’ve added sooo much new stuff. Head over to the project page to check out all the new features! Check out WP Smush Pro

Last month we re-released it with “super smush” – 60% average compression – and today we’re happy to announce you can now smush images up to 32MB.

But how does WP Smush Pro stack up against its competition?

We decided to find out. We pitted WP Smush Pro against its two biggest premium rivals, Kraken and EWWW, and the results were somewhat surprising.

Testing Image Compression

While researching ways to go about doing this testing, I came across developer Matt Cromwell’s excellent comparison post where he analyzed EWWW, TinyPNG and Kraken. Unfortunately, he left out WP (which is fair enough because it only smushes up to 1MB) and Smush Pro.

Since his tests in early March, WP Smush Pro has been revamped. It now smushes up to 32MB (which is more than enough, who uploads images that large anyway?), and we’ve put a helluva lot of work into improving WP Smush Pro (added “super smush,” bulk smush, backup, etc). WP Smush Pro is bigger and better and deserves another look in, so I decided to followed a similar testing methodology to Matt’s.

For this experiment I examined four criteria: pricing, features, ease of use, and compression.

I used Cloudways for the hosting environment.
I used Cloudways for the hosting environment.

Testing Environment

I wanted to ensure I had a consistent and stable hosting environment, so I set up a quick trial account with Cloudways using Digital Ocean with a server based out of San Francisco. It was a similar setup to Matt’s (mentioned above). WordPress 4.2.2 came pre-configured and I deleted any existing plugins.

The Theme Unit Test Data page in the Codex.
The Theme Unit Test Data page in the Codex.

Testing Images

I tested two sets of images:

Theme Unit Test Data: This test data is available to download from the Codex and includes 25 different images of varying sizes and colors.

Large Unsplash Images: I downloaded five images from Unsplash totalling 41.8MB, and ranging in size from 7.2MB to 9.7MB.

Testing Methodology

Here’s how I tested each plugin (after initial benchmarking):

  • Installed image compression plugin to be tested.
  • Imported the Test Unit Data and include file attachments (images).
  • Tested the Post Format: Gallery page with and recorded the First View Load Time and total size of images on the page, and compared this with the total size of images on the page as viewed in Chrome Developer Tools.
  • Uploaded Unsplash images. Since each plugin optimizes images when uploaded, I timed how long it took as a measure of ease of use.
  • Checked the total compressed size of the Unsplash images on a page displaying the images using Chrome Developer Tools.
  • Erased everything in my test site’s media library and moved on to the next plugins.

Note: Just to make sure my tests were accurate, I ran them each three times and recorded the average.

The Results

I must admit, I was surprised at the results. After my initial benchmarking, I tested WP Smush Pro first and was put off by how easy and quick it was to use, which is ridiculous. In the back of my mind I thought a plugin that was so easy to use surely wasn’t doing a good job. Surely it wasn’t working hard enough! I was also worried that testing would show that WP Smush Pro wasn’t as good as its competitors.

But then I moved on to testing Kraken and EWWW and felt silly for not having enough faith in WP Smush Pro. The results speak for themselves.

Theme Unit Test Data and the Post Format: Gallery page

Plugin Total Size of Images (KB) Percentage Savings (%) Page Speed (Seconds)
Original (no compression) 546 N/A 2.833
Smush Pro 319 42 2.448
Kraken 324 41 2.491
Ewww 532 3 2.938

Unsplash images

Plugin Total Image Size (MB) Percentage Savings (%) Total Upload Time
Original (no compression) 41.8 N/A 6 min 50 sec
Smush Pro 34.6 17 8 min 18 sec
Kraken 36.5 13 14 min 40 sec
Ewww 36.6 12 10 min 23 sec

WP Smush Pro was the clear winner, not only in terms of compression but also for ease of use.

Now for further analysis of the pricing, features and ease of use, here are my thoughts on each plugin.

Smush Pro
Smush Pro

Smush Pro


You can try WP Smush Pro for free for 14 days with a WPMU DEV membership and get access to 150+ other plugins and themes (including our amazing Upfront theme platform), as well as 24/7 support.

It’s also important to point out that you need to have an active membership into order to use the plugin since it needs an API to access our smushing servers.


WP Smush Pro now lets you smush images up to 32MB. That’s more than enough for most people’s needs.

The backend of the plugin includes options to auto-smush on upload (so you don’t have to individually smush images) and “super smush” for lossy optimization. This last option promises two times more compression than lossless, with almost no noticeable quality loss. You can also choose to backup original images, though this will nearly double the size of your uploads directory.

WP Smush Pro uses WPMU DEV servers to smush your images, so you don’t have to worry about additional load on your servers.

Ease of Use

The easiest way to install WP Smush Pro is using the WPMU DEV Dashboard, since you need the dashboard plugin anyway to link your member API to the plugin.

Once installed, the plugin has just one settings page, which you can access from the Media section in the sidebar.

Outside the settings page, you can view compression information and how much you’ve save for each individual image in the media library.


All you need to do is drag and drop your images onto the media library page and WP Smush Pro works in the background. As I mentioned above, the plugin was relatively quick at compressing the images and as first I thought it wasn’t working. When I checked the results I was pleasantly surprised to find I had saved 42% on the first lots of images and 17% on the larger Unsplash images.




All plans start out as a free account, which comes with 50 MB of testing quota, and you don’t need a credit card to sign up.

Here are the details of the premium plans:

  • Basic, $9 a month: 2GB of images per month, $4.00 per additional GB
  • Advanced, $19 a month: 5 GB, of images per month, $3.00, per additional GB
  • Premium $39 a month: 15 GB of images per month, $2.00 per additional GB
  • Enterprise $79 a month: 60 GB of images per month, $1.00 per additional GB

All plans include access to Kraken’s API, and a web interface where can upload one-off images for quick compression . The WordPress plugin is listed as included in the plan even though it’s already freely available to download from anyway.

There’s also a Micro plan for $5 a month, which includes 500MB of images per month and each additional GB is charged at $5.


Kraken lets you “krake” images up to 16MB. The service also uses its own servers for compressing images.

Other features include the ability to resize images using one of several strategies prior to optimization, though you can only do this with the web interface, not the plugin.

Ease of Use

Installing and activating the plugin is a fairly straightforward process

Like WP Smush Pro, Kraken keeps things simple and doesn’t offer too much in the way of settings. When you install the plugin, it adds a settings page to the Settings section in the WordPress admin sidebar. From there, you can add your API key and secret, whether you want lossy or lossless optimization, and also allow new uploads to be automatically optimized.

You need to login to your account on the Kraken website to access your API and manage your account and billing details. The account dashboard provides a nice overview of your total image compression statistics and average savings, though there’s no way to view statistics for individual images.

After initially signing up for a free account I realised the 50MB limit on images wasn’t going to be enough, so I signed up to the Micro plan. The account dashboard offered a convenient way to monitor how many images I was compressing.

While the first batch of images didn’t take very long to upload, the Unsplash images took almost 15 minutes! That’s almost twice as long as WP Smush Pro.


While the compression for the initial set of images was comparable to WP Smush Pro and the savings on the Unsplash images was good, uploading the images was very slow.




EWWW requires a $1 upfront payment (which includes 200 credits) and then charges per image:

  • First 1,000: $0.005 per image
  • 1,001 to 5,000: $0.004 per image
  • 5,001 to 10,000: $0.003 per image
  • 10,001 and after: $0.002 per image

It doesn’t matter how big the images are, just how many you compress. So if you compress 1000 images it will cost you $5 and 10,000 images will cost you $20.

There is also a minimum charge of $1 a month, but if you don’t use any credits in a given month you won’t be charge. If you use less than 200 credits in a month, your $1 minimum monthly payment will give you credit into the following month.


EWWW lets you compress images up to 16MB each, though the terms of service ask that you “please contact us if you think this is unrealistic.”

While the plugin can run on your own server, for the purposes of this test I used the premium cloud server option and allowed EWWW’s servers to do all the heavy lifting.

Like Kraken and WP Smush Pro, EWWW can automatically optimize images as you upload them to your site. It can also optimize existing images and convert images automatically to the file format that will produce the smallest image size (though this last feature comes with a big “warning” stamp). You can also optionally apply lossy reductions for PNG and JPG images.

By default, the EWWW Image Optimizer Cloud plugin uses lossless optimization techniques, so your image quality will be exactly the same before and after optimization.

Ease of Use

After reading through EWWW’s imposing terms of service on the website’s pricing page, I signed up for a premium account and downloaded the EWWW Image Optimizer Cloud plugin.

The plugin added two new menu items to the Media section in the WordPress sidebar: Bulk Optimize and Unoptimized Images. It wasn’t immediately clear how I should use the plugin so I watched the installation video at to work out what to do. I realized a third menu item for additional settings had been added to the Settings section in the sidebar. I should point out here that the installation video goes for 16 minutes and I didn’t make it through to the end.

I received an email from EWWW with my API key and added this to the plugin (I found it odd that you can’t access your API key when you login to your account on the EWWW website, you can only access your personal and billing details), checked the options for JGP and PNG cloud optimization, and also double checked that I was using lossless optimization so the results were comparable to the testing I did for WP Smush Pro and Kraken.

The first time I tried to upload the Theme Unit Test Data the plugin timed out, so I tried again, and then a third time. Since I was using Cloudways, I was able to quickly increase my maximum upload limit to 32MB (it was originally 10MB). It still didn’t help. I then did a database reset so my install was clean and reinstalled EWWW before uploading the Theme Unit Test Data again, and that seemed to do the trick. Still, I wasted about 30 minutes trying to work things out.

I didn’t have any problems at all uploading the Unsplash images.


While the compression for the Unsplash images was comparable to Kraken, the compression for the Theme Unit Test Data was woeful – just 3% and not really worth the time and effort.

And the Winner is… WP Smush Pro

The results speak for themselves: WP Smush Pro was the clear winner both in terms of the level of compression and the time it took to compress images.

Smush Pro is the best premium image compression plugin for WordPress.
WP Smush Pro is the best premium image compression plugin for WordPress.

WP Smush Pro was easy to set up and handled the Theme Unit Test Data images with ease. The plugin didn’t miss a beat compressing large Unsplash images I threw at it.

By contrast, EWWW was fiddly and time consuming to set up and caused my site to timeout. Kraken’s savings were good, but it was really slow at compressing the large images.

While WP Smush (formerly WP has been a popular free option for many years, WP Smush Pro is a relative newcomer to the premium image compression market. For diehard fans of Kraken and EWWW, WP Smush Pro still has a lot of convincing to do, though I hope the results of this image comparison testing will prove it’s a serious contender backed by a fantastic team of developers who are constantly working to improve it.

And just to throw a few numbers at you, here are the stats for WP Smush Pro over the past month (up until May 17): 62.8 million images smushed on 124,136 different WordPress sites with an average saving of 9%.

Have you used WP Smush Pro? What's your experience using the premium versions (not free!) of Kraken and EWWW? Tell us in the comments below.

Raelene Morey

Raelene Morey Raelene is the Founder of Words By Birds, a digital writing agency that works with startups, SaaS, B2B, and WordPress businesses on turning tech speak into words that convert. She was formerly the managing editor at WPMU DEV. A computer science grad turned newspaper journalist, when she’s not taming browser tabs, she likes brunching and bushwalking.