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Welcome to Caesium!

Caesium reduces the size of pictures up to 90%, preserving the original visual quality.

Caesium allows you to save a lot of space on your hard drive and quickly upload your pictures on the web (on sites like Facebook, Google+ etc) saving a lot of time. Also webmasters and bloggers need to make sure the images they post on their websites are optimized, to avoid prolonged loading times for their visitors.

Save space

If you have a lot of pictures in your hard drive, maybe it's time to compress them. You can save a lot of space by just putting all these pictures on Caesium and let it do his job. Caesium works great with high resolution photos from cameras.

Load faster

If you are a webmaster or a blogger, you will probably upload a lot of pictures. And what about your visitors? If your pictures are not optimized, their loading time will be very long and they will just go away. Before posting your pictures, let Caesium compress them!

Send quickly

Sending your holiday photos by mail could be very slow if they are not optimized. You can save up to 90% of your time by just compressing them with Caesium. This also applies for Facebook, Google+ and other social networks or platforms.

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Compress up to 90%

Caesium can reduce the size of your pictures up to 90% without changing the file format and without requiring additional softwares for opening them. This process preserves the original visual quality and so your pictures will look like the originals.

Batch processing

You can open hundreds of pictures with Caesium and compress all of them at the same time, saving a lot of time. Caesium also supports subfolders allowing to work on complex directory structures without changing them.

Instant preview

You can set different compression level to all your pictures and see your results instantly with an simple side-by-side preview with the original and compressed images, supporting zoom and custom visualization options.


If you are looking for an aggressive compression, you can also change the pictures resolution, allowing to significantly drop down the file sizes. Caesium supports percentage and absolute resize, always working on batch.

Extra features

Caesium supports all the common file formats, has a multilanguage interface, supports Metatag (EXIF) and timestamps. Also supports Drag&Drop, tray minimization, automatic updates and much, much more.

Completely Free

Caesium is an OpenSource project and it's completely free to use. You don't need to pay anything to enjoy all the features. You can also support this project in many ways. See the About section for additional details.

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Caesium is an Open Source project developed by Matteo Paonessa. Is a fully free software and you can use it under the terms of the license.

Software License

This work is released and licensed under the GNU General Public License, that means "you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs."

More about this project

When I started building Caesium, it was a small testing project about pictures compression. The first version was very very simple, slow and not very handful. But people started downloading it and giving suggestions, asked for new features and so on. Some of them gave me translations some others, who I really want to thank, donated to this small project.

Now Caesium is a better and quite complete software for its use, but can be better. For example, there's no Linux or Mac version, the PNG compression is incomplete and I have some interesting other ideas to implement. But, sadly, I have no fund to invest in. I'm the only developer and I am an Italian IT University student, nothing more. I can't afford invest many money on this project.
My first goal is to build Caesium for every common platform or operating system around, tablet and smartphone included. I want to port Caesium to Android, Windows Phone and iOS (as well as Linux and Mac OS X).

It would be very nice to compress your pictures on your phone without using a PC and, for iPhone or iPad, Caesium would be hardly optimized for those platforms.

Thanks to everyone who will contribute to this project.

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Caesium is available for any Windows OS. A Linux Alpha version is currently under development. Mac version will not be available in the near future.

v1.7.0 - 26/11/2013

Source Code Pack

All downloads are hosted by external platforms. The first mirror is always recommended. If any mirror doesn't work, try with another one.

Other Download options - Changelog - MD5 - SHA1

Check out this Caesium Quick Look video while downloading:

Caesium Quick Look Video by

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If you have an question, problem or suggestion, please contact me with this form or send an email at matteo.paonessa [@] gmail [dot] com


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