RIOT 2026.10 – Free Image Optimizer

(17 votes, 3.59)

2026-09-30 00:00 6236

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Description

Changelog

Specifications

RIOT (Radical Image Optimization Tool) is a free image optimizer that will let you to visually adjust compression parameters while keeping minimum file size. It uses with a side by side (dual view) or single view interface to compare the original with the optimized image in real time and instantly see the resulting file size.

It is lightweight, fast and simple to use, yet powerful for advanced users. You will be able to control compression, number of colors, metadata settings and much more, and select image format (JPG, GIF or PNG) for your output file.

Also you can integrate RIOT as plug-in in well known programs like The GIMP, IrfanView and XnView.

Main features of RIOT:

open many image types including rare/scientific types
save and optimize JPEG, GIF, PNG and Web with a simple, clean user interface
automatic optimization selects the most suitable format and parameters
works in dual view: (original – optimized image) or single view (optimized image).
automatic preview of resulting image
in-place compare function (alternativelly display the original image over the optimized image to notice small pixel changes)
compress files to desired filesize threshold
fast processing
batch support (process multiple files at once)
transparency handling options
decide if you want to keep metadata (comments, IPTC, Adobe XMP, EXIF profiles, ICC profiles).
transfer metadata between image formats (destination format must support them)
common tools: pan and zoom, rotate, flip
basic image adjustments: brightness, contrast, gamma, invert
visually reduce number of unique colors for PNG and GIF images in order to reduce filesize
(two quantization methods are available: Xiaolin Wu and NeuQuant neural net)
resize image by using well known resample filters (ex: Lanczos3, Catmull Rom, Bicubic, and others)
out-of-the-box support for external PNG optimizers (optipng, pngout, etc)
the compression and the results are comparable to those of commercial products, even higher.
Adaptive logarithmic tone mapping algorithm (Drago) used for HDR images

Input image types

common bitmap images as well as Adobe Photoshop PSD files
popular HDR formats and RAW camera images
rare/scientific types (up to 128 bpp, integer and floating point)

Changes in RIOT 2026.10 (2026-09-18):

Desktop

Add folder and Add folder (recursive) in the file menu; drop folders onto the list (prompt if they contain subfolders).
Command line: –folder and –folder–recursive (repeatable; –folder-recursive is an alias).
Positional image arguments and file-manager Open with: one file opens in compare, several are added to the list.
Preset: Default Settings and Last Used. Last Used stores encode, handling, extra operations, and automatic preview; destination folder is not part of the preset.
Preferences remember last add/output folders and which always-on panels are expanded.
Windows portable zip: settings in riot-gui.ini next to the exe when that file is writable.

File handling

If a file exists: Don’t replace (skip), Use a unique name (default), or Replace.
Format-change unique names: photo.png.webp, then a timestamp. Same format: photo_timestamp.jpg.
Replace does not overwrite a different extension unless “Allow replacing a different format” is on.
Existing siblings (for example photo.webp next to photo.png) are not overwritten by a format change unless that checkbox is on.
Keep-original (auto encode not smaller) is a warning, not a silent success. Don’t replace / unique name leave the source bytes alone.
Delete originals only after a different optimized file is written.

Fixes

Optimization summary reports skipped items and warnings as well as failures.
Warning when the written file is larger than the original (manual / resize / format change).
Unique names are not created for a keep-original copy that would be discarded.
Don’t replace skips an in-place re-encode instead of rewriting the source.

Homepage – https://riot-optimizer.com/

Supported Operating Systems: Windows 7, 8, 8.1, 10, 11.

Size: 37.6 MB