Reading an Apple ICNS file
An ICNS container can hold several icon representations for different macOS sizes and display densities. This viewer validates the icns signature, walks the chunk table, reports each four-character chunk type and byte length, and previews payloads the browser recognizes as PNG, JPEG, or JPEG 2000.
Preview versus raw extraction
Not every chunk is a ready-to-display image. Older ICNS files may contain legacy RGB planes, masks, compressed pixel data, or metadata. Those chunks are still listed and can be downloaded as their original payload bytes even when the browser cannot preview them.
- Choose, drop, or load an
.icns file. - Review the container metadata and chunk list.
- Preview supported images or download individual chunks for offline conversion.
Chunk extraction does not alter the original file. Local bytes stay in the browser; URL loading requires permission from the source server.
