What it does
Caesium is a free image compressor with a real-time preview, batch processing, metadata options, folder-structure support and a command-line tool.
Use the live preview while choosing compression and metadata settings, preserving folder structure when the delivery set needs its organization. Desktop, CLI and online editions have separate routes and conditions. The GPL3 desktop repository lists 64-bit Windows 10 build 1809+ and macOS 12+; Linux guidance names tested distributions and self-build or third-party binaries. Use a stable tag for source builds because the main branch may be unstable. Exact output naming and backup behavior remain unverified.
Strengths
- Real-time preview
- Metadata and folder-structure options
Best for
- Compressing organized image collections
Sources
- Caesium - Image Compressor (Oct 26, 2026)
- Caesium GPL3 stable/platform and source-build scope (Oct 26, 2026)