When it comes to website speed, Image optimization has never been so important as it is now. That is because images continue to be the largest resource in a web page but also because an ever larger number of people use mobile devices. And as we all now, mobile devices are usually not as fast or well connected as the laptop on your desk.

If you also consider that 1 in 4 websites worldwide use WordPress (yes, that is 25%+ market share) you’ll realize why the WP image optimization plugins are so important: they can be used to optimize 25% of the web. Quite a task!

Now, I spent a day testing all the WP image optimization plugins I could find and compiled a list with them so it would help you save a day and make a decision faster.

Please note that I included in this list only the plugins that are able to do “cloud” optimization. There are also plugins that can perform the optimization on the server where the WP site is hosted but I don’t like them as you (usually) need to install additional software and they can significantly load your system. That’s especially bad for shared hosting.

Here’s a short, alphabetically sorted, list with all of them so you see them all at a glance:

  • EWWW
  • Kraken
  • Optimus
  • ShortPixel
  • TinyPNG
  • WP Smush

Now let’s take them one by one and see what’s up with them:

EWWW Cloud

I couldn’t test it, it has no free plan though it is listed on WP repository. Strange.

ShortPixel

A simple to use plugin with a clean interface and useful features. You need to subscribe to ShortPixel to get the API Key and get the plugin going. Upon subscription you receive 100 free credits/month. While it isn’t as many as those offered by TinyPNG they should be enough for the average WP blogger. Also, this plugin only counts the images they succeeded optimizing by at least 5%. Otherwise no credits are charged. Interesting deal.

It is the only plugin I tested that offers a backup and restore solution for the optimized images so it should be safe give it a try.

What I felt was missing was more free credits 🙂

Plans start at 4.99$/month and one-time packages are also available. You can optimize 10,000 images with $9.99 which is a good bargain especially if you have large images.

Kraken

It is a simple to use plugin with just a few options and a clean interface. Compared with other plugins its optimization capabilities are in the low end. It can automatically optimize images but there is no backup.

In case an image isn’t properly optimized there isn’t an easy way to restore it. If you upload many images at once and have Automatically optimize uploads: setting checked it would take considerably much more time to finish uploading the files.

What I believe it lacks the most is the ability to bulk process all the images by clicking a single button.

Oh, and they haven’t updated their plugin since 9 months. It makes me wonder…

Its free plan includes 50MB/month and their paid plans start at $9/month. There is no option for one-time payments.

TinyPNG

What I like about TinyPNG is that they have the option to optimize only certain image sizes, they offer the option to resize the original image (it can lead to great savings) and they have a generous free monthly plan (500 images/month for free).

What I didn’t like is that they offer no backup option, the optimization results are in KB/MB (it is rather confusing for me) and there is only the option to optimize the images as lossy.

While testing their plugin I could notice blurry sections on some pictures. While they didn’t look very bad it wasn’t nice for the trained eye either.

TinyPNG have a generous monthly plan of 500 images and also the option to pay exactly what you need. So if you need to optimize only 3500 images then you only pay for that.

The cost for optimizing 10,000 images is $85 which is rather high.

Optimus

It was easy to test this plugin as it doesn’t require an API Key to work. But in its free version it is quite limited: you can only optimize images up to 100KB and advanced features aren’t available.

Even if you paid for it you could only optimize images up to 5MB, they cannot be rescaled and there is only the option to optimize them as lossless.

What I liked at this service the most is the pricing: they offer a $19/year unlimited plan. While certainly not the best or versatile plugin the pricing could be a good deal for someone that can live with average optimization and limited features.

WP smush

This plugin is sort of the grandfather of the WP optimization plugins. It used to work on Yahoo’s API but they turned it off at one moment and the plugin was sold to WPMU DEV. While being the optimization plugin with most downloads and users it is rather a demo version of what the PRO plugin could do if you spend $19/month.

There is no need for an API Key to run (or just test) this plugin which is great but it only optimizes files under 1MB and many if not all the features aren’t available unless you pay for them. The PRO version seems to be feature-ladden which is good but I haven’t got yet the opportunity to fully test it. I may update this article once I got the chance to do it.

Now here are 2 tables to help you put in perspective how different plugins perform.

A simple optimization test on 4 types of files (an archive with the files is available here link to be added)

Service/Type JPG PNG GIF PDF
Kraken 51.66% 75% 32.35% N/A
Optimus 82% 25% N/A N/A
ShortPixel 96.73% 74.93% 27.51% 88.76%
TinyPNG 98.22% 75.61% N/A N/A
WP Smush 43.5% 0% 27.2% N/A

Notes:

  • TinyPNG plugin has the best optimization for PNG and JPEG but ShortPixel comes very close
  • ShortPixel has the ability to optimize most of the file types while coming close to TinyPNG in terms of optimization power
  • Kraken performed average on JPG but did best on GIF optimization
  • WP Smush to my surprise did worst on all the file types with the mention that it didn’t even try to optimize the PNG file, it considered it “Already optimized”. Really?

The features/options I considered most important in a simple to compare table

Service API Key Backup Bulk Lossy Free/m Max size Resize
Kraken Yes No No Yes 50MB 32MB No
Optimus Paid No Yes No 5MB No
ShortPixel Yes Yes Yes Yes 100 Yes
TinyPNG Yes No Yes Only 500 ? Yes
WP Smush Paid No Yes Paid 1MB Paid

Notes:

  • For WP Smush and Optimus only the free/demo versions were tested. I expect them to do better for the paid version
  • I couldn’t figure out what’s the maximum files size limit for TinyPNG but while testing I haven’t reached it 🙂
  • Kraken is the only plugin without an option for bulk optimization

To learn more about improving the search performance and engagement of content on your blog, be sure to also check out our SEO Tools for 2016 and Organic Search Optimization tips.

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