imageopt

Free plan LinuxMacWindows

What imageopt is

imageopt is a free command-line image optimizer for local work and CI automation on Linux, macOS, and Windows. It processes JPEG, PNG, WebP, SVG, and static GIF files; animated GIF, animated WebP, and AVIF are skipped. Compression is lossless by default, with optional lossy recompression, but image resizing is not supported. Batch workflows can use recursive paths, dry runs, backups, JSON reports, and a check mode that returns an error when optimization is possible or a file fails. The engine re-decodes candidates, keeps the smallest valid output, writes atomically, and leaves failed files untouched. A composite GitHub Action can optimize files, commit results, or gate pull requests. Prebuilt binaries cover listed desktop architectures; source installation requires Cargo and stated build tools. The project is GPL-3.0-or-later.

Who it suits

It suits developers and build pipelines that need local, scriptable optimization without a paid plan. GitHub users can use the composite Action for repository workflows.

What it does well

Free GPL-3.0-or-later software
Supports Linux, macOS, and Windows
Offers batch, recursive, and dry-run modes
Provides JSON reports and check mode
Includes GitHub Action automation

What to know first

Image resizing is not supported
Animated GIF and WebP are skipped
AVIF files are not optimized
No API access is listed

Plans

Plan	Billed and limits	Price
imageopt	GPL-3.0-or-later · CLI and GitHub Action · no paid plans or usage limits stated	Free

As github.com lists them, read 9 Oct 2026. The maker's own page has the final word.

Verdict

imageopt focuses on safe, automatable compression from the command line and GitHub Actions. Its format exclusions and lack of resizing make it better for optimization pipelines than general image conversion.

Facts from imageopt's own pages

Action platforms: The composite action supports Linux, macOS, and Windows, and downloads a release binary with SHA-256 verification. · github.com, 9 Oct 2026
API access: No · github.com, 24 Sept 2026
Batch processing: Yes · github.com, 24 Sept 2026
CLI features: The CLI supports dry runs, backups, recursive paths, JSON reports, and a check mode that exits with an error if images could be optimized or a file fails. · github.com, 9 Oct 2026
Compression: Optimization is lossless by default, with lossy recompression available as an option. · github.com, 9 Oct 2026
Compression modes: both · github.com, 24 Sept 2026
Downloads: Prebuilt binaries are listed for macOS arm64/x64, Linux x64/arm64, and Windows x64. · github.com, 9 Oct 2026
Formats: It optimizes JPEG, PNG, WebP, SVG, and static GIF files; animated GIF and animated WebP are skipped. · github.com, 9 Oct 2026
Free plan: Yes · github.com, 24 Sept 2026
GitHub Actions: A composite GitHub Action can optimize files, commit results, or gate a pull request when images could shrink. · github.com, 9 Oct 2026
Installation: Users can download a platform binary or install from source with Cargo; building requires Rust 1.82, a C compiler, nasm, and cmake. · github.com, 9 Oct 2026
License and pricing: The software is licensed GPL-3.0-or-later; the opened project pages state no price. · github.com, 9 Oct 2026
Metadata controls: Yes · github.com, 24 Sept 2026
Notable limits: AVIF is detected and skipped, and animated GIF and animated WebP are not optimized. · github.com, 9 Oct 2026
Purpose: imageopt is a cross-platform command-line image optimizer for local use and CI automation. · github.com, 9 Oct 2026
Image resizing: No · github.com, 24 Sept 2026
Safety: The engine re-decodes candidate outputs, selects the smallest valid result, and writes files atomically. · github.com, 9 Oct 2026
Security and reliability: The project says it guards against decompression bombs and leaves failed files untouched. · github.com, 9 Oct 2026
Supported formats: JPEG,PNG,WebP,SVG,static GIF · github.com, 24 Sept 2026

Where imageopt stands on Freedom251

Image Compression Software#25 of 85