Best free image optimization plugins for WordPress (top 7)

Compressing images is an easy task on WordPress with image optimization plugin.

But which one to choose?

I’ve been using WP Smush until I realized it doesn’t optimize the original image size in the free version which was a big problem for me.

I tested 7 most popular WP image optimizer plugins to find the best one – ShortPixel.

Here’s the breakdown

WordPress image optimizer plugin reviews

All of the reviewed image compression plugins have at least 20,000 active installations each and they are regularly updated and maintained.

You can install and use any of these plugins for free, but they all have premium versions/plans so free options have certain limitations.

I tried them all and ranked them taking into consideration the following factors:

1. List of features in the free version
2. Compression performance in the free version
3. Limitations in the free version

#1. ShortPixel Image Optimizer

ShortPixel image optimizer gives all of their features for free and I love it.

And compression is great. You can even choose three levels of compression:

• lossy,
• lossless,
• glossy

Furthermore, you can optimize PDF files as well. You can even convert PNG images to JPEG or create WebP versions of the images.

There is only one limitation in the free plan: you get to compress 100 unique images per month. But that is still much more generous than what other plugins offer for free.

It is actually much more than I need for this website. If you do need more, there are paid plans available, but they are very affordable, starting from only 5$ for 5000 images which should really be enough for 90% of the users.

In order to install ShortPixel you need to sign up for free and get the API key. The process is extremely easy, just enter your email and you get API key in your mailbox.

You can check out the their online tester to see the results before installing the plugin.

ShortPixel plugin grades

#2. Compress JPEG & PNG images

Compress JPEG & PNG images by TinyPNG is a simple but effective plugin that allows you to compress JPG and PNG images, just how it’ s name suggests.

However, it doesn’t offer any extra features outside of that.

Additionally, it requires API to work that allows you to optimize up to 500 images per month for free. If that is enough for you, this plugin is a good choice.

Just be careful, this cap of 500 images include alternative image sizes as well.

For example, my theme creates 9 alternative image sizes alongside original, if I choose to optimize them all, this means I can compress total of 10 unique images per month if I don’t exclude some (or all) of the alternative image sizes from compression.

Compress JPEG & PNG images plugin grades

#3. Smush Image Compression and Optimization

WP Smush is the most popular image optimizer out there with 1+ million active installations, however the free version has a huge downside and that is why it’s not first on my list.

WP Smush doesn’t optimize the original image in the free version of the plugin!

That means all of the alternative image sizes that are created automatically by WordPress on upload can be compressed, but not the original version. The one that you actually upload.

If you are using original image versions on your pages, which is most often the case, then you miss out big time. Your pages won’t have optimized images at all! At least not on desktop devices.

I always upload images in the exact size I need for my articles, and most of the visitors to this website use desktop devices.

By using free version of the Smush image optimizer plugin I would be serving unoptimized images to 90% of my readers!

WP Smush plugin grades

#4. EWWW Image Optimizer

No API key needed to start using EWWW Image optimizer, but without it you are restricted to lossless image compression only.

API key will cost you just 0.99$ and after that, you are billed 9$ on monthly basis, but only when you use 3000 credits (compressed images).

I didn’t purchase the API key, but they promise around 80% compression, just like the other plugins do.

If that is true, depending on your requirements, if you go for the paid version, it would likely be cheaper than Imagify or Kraken.

This is the only reason I placed EWWW image optimizer higher on the list, despite a very limited offer in the free version.

EWWW Image Optimizer grades

#5. Imagify Image Optimizer

Next on the list is Imagify. This plugin requires registration to get the free API key as well, but free plan allows you to optimize much more images than Kraken does.

You get 25MB per month for free. However, while I was testing the PNG compression, I got a warning: File size must be under 2.0 MB. Current file size is 2.2 MB. Big problem there!

Imagify Image Optimizer grades

#6. Kraken.io Image Optimizer

Kraken requires API key for activation, but it offers more features than Optimus. Unfortunately, there is also a huge limit in a free version.

Not in file size, but in free quota that you get – only 100 MB of images to optimize.

Despite the good compression result, this means that if you are looking for free image optimization plugin, Kraken is most likely not going to cut it.

Kraken.io Image Optimizer grades

#7. Optimus–WordPress Image Optimizer

Optimus is very easy to set up and configure, but at the same time that means it lacks in features other image optimizers on this list have.

Itsupports only lossless compression of PNG images and a slightly lossy compression of JPEG images.

On top of that you are limited to images up to 100 KB in size in a free version of the plugin. I picked one image 1280×800 px that was 145 KB and couldn’t compress it within free version… Serious problem there.

Optimus–WordPress Image Optimizer grades

Conclusion

ShortPixel is easily the best image optimizer plugin for WordPress.

It offers all of the premium features in the free plan, and they really do have the best set of features among all of the tested plugins.

All other plugins need paid license to unlock all of the features, but that’s not the case with Shortpixel!

Just sign up here for the free API key with your email and make your site load faster for free.

Shortpixel offers the most features for free, but it also performs well. I used the jpg image below and optimized it using the top three image optimizer plugins from this list.

The image you see below is optimized by ShorPixel plugin. This compressed version has the size of 88 KB while the original had 291 KB.

Check out the table below to see how that compression compares to the WP Smush (see compressed image) and TinyPNG (see compressed image).

So if you see the Optimize images warning in GTmetrix report, install ShortPixel image optimizer. Your users will be grateful and convert better 🙂