If you run a WordPress site, or any other website for that matter, it can be hugely beneficial to optimize the images that are uploaded to your media library. Many images can be compressed to much smaller sizes which will speed up page rendering for your readers, save on storage space and reduce data transfer costs. GeekWire is currently using Kraken.io to optimize all of the images that you see on the site.

Image optimization statistics

GeekWire currently uploads over 1000 new images each month, sometimes more. Since WordPress creates a variety of post thumbnail sizes for display in our theme, that translates into 10,000 or more image files that we add each month, representing over 1GB in file size.

Once you reach a certain traffic threshold, your web hosting provider begins charging for data transfer as well. Our current CDN provider charges us $0.12/GB for outgoing data, which is mostly images on our site. We pay over $1,000 each month in data transfer fees alone, so the costs are significant.

Using Kraken.io

Kraken.io is a web service where you send it an image file and it returns a compressed version of the file. The images can use either lossless or lossy compression algorithms. Many images can be losslessly-compressed to remove redundant or unneeded data in the image file. By sacrificing a small bit of image quality, often imperceptible to viewers, lossy compression can drastically reduce image file sizes in many cases.

Kraken.io offers a WordPress plugin┬áthat intercepts images from the media uploader before they are saved on your server and sends them to the Kraken.io web service to be optimized first. The plugin also allows you to optimize existing images in your media library that haven’t been “Krak’d”.

Kraken.io is not a free service, but offers prices based on the size of images that you optimize each month.

Our results

We are currently using the Kraken.io lossless compression algorithm and have optimized over 9GB worth of images with an average savings of 18% of file size. In our case, an 18% reduction in image file size directly reduces our outgoing CDN data transfer charges by 18% as well. The savings on CDN costs more than outweighs the cost of the image optimization service, and of course anything we can do to reduce page load times is beneficial to our readership.

Kraken.io optimization results

The Kraken.io WordPress plugin works well in our editorial workflow. It requires no interaction from our authors. The Kraken.io service is fast, but it does take a little bit longer to upload files to the media library while it waits for all of the optimized thumbnails to be returned. The delay is worth it to achieve the image optimization results.

If you are running an image-heavy WordPress site, it is definitely worth looking into image optimization solutions.Yahoo’s Smush-It service was a great free alternative for image optimization in WordPress, but given its recent demise, other options like Kraken are worth a look.


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