Frequently Asked Questions

No. ImgZilla compresses entirely on your Mac, no network needed — your image data is never uploaded to any cloud.

Built-in deep optimization tuned per format compresses heavily while keeping images sharp, averaging over 50% and up to 90%+. You can also use the built-in compare tool to see the before/after difference.

With original backup enabled, the original is automatically saved to the Trash before compression and can be recovered anytime. (Note: for disks that don't support the Trash, you'll be prompted to set a backup folder.)

JPG, PNG, GIF, SVG, HEIC/HEIF, WebP, AVIF and other mainstream image formats.

There's a free daily allowance; for heavier use you can choose a one-time purchase or a subscription to fit your needs.

No. ImgZilla specifically protects the alpha channel data throughout compression, so transparency is always preserved.

Logos and icons typically shrink 10–20%, screenshots and photos often 20–30%, depending on image complexity.

Photos are better as JPG. PNG is best for images with transparency, text, sharp edges or large flat color areas.

Yes. Lossless compression only removes metadata and optimizes file structure, with zero quality loss.

The before/after difference is nearly imperceptible, typically shrinking 50–80% (e.g. 4MB down to 800KB–1.2MB).

No. Compression happens entirely locally; your images never leave your device.

They're exactly the same format, just different file extensions, stemming from early Windows limits on extension length.

The online tool is great for a few images quickly; the desktop app supports unlimited batches and multi-threaded whole-folder compression.

No. Optimization only removes redundant code and trims precision; the rendered graphic stays visually identical to the original.

Design-tool exports typically shrink 10–30%, depending on the redundant data and path complexity.

The default cleanup preserves necessary ids, classes and animation structure; if in doubt, you can re-verify after compression.

SVG is vector text, so it compresses code rather than pixels — the result is lossless and infinitely scalable, whereas bitmap compression targets pixel data.

Every frame is a full image with its own palette. A 3-second, 15fps animation is 45 frames — size adds up fast without optimization.

No. Optimization only targets data redundancy and color efficiency; duration, frame count and look are all preserved.

Yes. A GIF's binary transparency is fully preserved throughout compression.