Caesium Image Compressor

Caesium Image Compressor Review: Shrink Photos, Keep the Detail

Waiting forever for images to upload? Watching your disk space vanish? Caesium can help you reduce the size of images.

What is Caesium?

Started in the early 2010s by Italian developer Matteo Paonessa. Still going strong. It’s free, open-source and doesn’t hide anything behind paywalls. Strips image size down by a lot—up to 90% in some cases—and still keeps them looking how they should. No weird colour shifts. No pixel soup.

First run

Windows version's under 22MB. Took a minute to download and open. Nothing extra bundled. There’s one for Mac and Linux too, and even a web version at caesium.app. Light, clean, no fluff.

Using it

Drag. Drop. Done.

You pick the quality. See the file size before and after. Queue up a single image or dump in a few hundred. The preview lets you double check. No zoom in the preview, sadly, but still—easy enough to trust what it shows.

Everything’s responsive. Doesn’t feel dated. Doesn’t act like it’s trying to be smart—it just is.

What makes it good?

If I’ve got a batch of photos for a client or site, I throw them in, set compression around 75%, and hit go. It does the job, fast. Keeps the sharp bits sharp. Keeps colours balanced. Handles JPG, PNG, WebP and TIFF. Lets you swap formats too.

Privacy? You can strip EXIF data. You don’t have to, though.

There’s a command-line version if you like scripts doing the work while you drink your tea.

Is it stable?

Very. Pushed thousands of files through it. No crash. Ran 50 five-megabyte JPGs on an older laptop and it churned through them in under two minutes. Still looked great afterwards.

Compared with others

Here’s how Caesium stacks up with other image compressors:

Software	Offline	Batch Support	Format Options	Speed	Compression Control
Caesium	Yes	Yes	JPG, PNG, WebP, TIFF	Fast	Yes
ImageOptim	Yes	Limited	JPG, PNG	Medium	No
TinyPNG/TinyJPG	No	Limited	JPG, PNG	Fast	No
RIOT	Yes	Yes	JPG, PNG, GIF	Medium	Yes
FileOptimizer	Yes	Yes	Broad range	Slower	Advanced settings
OptiImage	Yes	Yes	JPG, PNG	Fast	Yes

Who’ll find it handy?

Useful for photographers who can use it to cut bulk from galleries.
Great for the web developers to make their sites load faster.
Social media folks gets under size limits without mangling the visuals.
Anyone sending photos via email, WhatsApp, or uploading to other platforms that has a limit.

Free means free

No ads. No pop-ups. No locked features. You can even chip in on GitHub if you like fixing or tweaking stuff.

Final thought

Don’t overthink it. Try it once. You’ll use it again.

No release notes available