ImgZilla User Guide

Eight formats are supported: JPG / JPEG, PNG, GIF, SVG, HEIC / HEIF, WebP, AVIF.

Files in other formats (along with hidden files and directories whose names start with .) are skipped automatically when you add them.

Two ways, with identical results:

• Drag and drop: drag files or folders straight into the window.
• Click to choose: click the logo area in the middle of the window and pick files or folders in the panel that opens.

When you drop a folder, ImgZilla searches it recursively for images (directories nested more than 20 levels deep are skipped with a notice). Duplicate files are only added once.

If your selection contains no supported images at all, a message tells you which formats are supported.

The bottom bar shows "Finding images" along with a "Cancel" button. Click it to stop the scan — the files already found stay in the list.

Once your list is ready, click Start Compression in the bottom-right corner. Images are processed one by one in order, and the item currently being compressed scrolls into view automatically.

• While compression runs, the button becomes Stop Compression — click it to abort at any time.
• When everything is done you get a system notification, and the button becomes Clear (clears the list and returns to the start screen).
• The bottom bar shows the number of files processed plus the percentage and size saved, in real time.

Hovering over the list pauses the auto-scrolling so you can read it, and a small bar floats up at the bottom showing the image currently being compressed.

Yes. ImgZilla compresses in place: the result is written back to the original path, keeping the same file name and location.

By default your originals are not lost — see the next section.

With the default settings, yes, you can recover them. On a successful compression the original is first moved to the system Trash, and only then is the compressed result written to the original path. To restore one, just open the Trash and choose "Put Back".

This behaviour is controlled by the "Move originals to Trash" switch in Settings, which is on by default.

You can, but once it's off, compression overwrites the original file directly and the original cannot be recovered. You'll be asked to confirm. We recommend turning it off only if you have another backup or are short on disk space.

Some locations (external disks, network volumes, or cases where the system granted access to a single file but not to its parent folder) don't allow moving files to the Trash. When this happens, compression pauses and a dialog asks you to choose:

• Choose a backup folder: pick a folder; originals are copied there before being overwritten. That folder is also remembered as your default backup folder.
• Skip backup: after a confirmation, originals are overwritten directly with no backup kept and no way to recover them.
• Close the dialog: treated as a cancellation — the whole compression job is aborted.

Your choice applies to all remaining files in this run; you won't be asked again for every image.

It is created automatically on first launch at:

~/Library/Application Support/ImgZilla Backups/

Each compression session creates a new time-stamped subfolder inside it (for example 2026-07-12_14-30-05).

Every successfully compressed image in the list has a Compare button on its right. Clicking it opens the image comparison window with the backed-up original on the left and the compressed result on the right. See section 4 for details.

It controls whether metadata inside the image (capture settings, GPS location, ICC colour profile, and so on) is kept.

• Off by default: metadata is stripped, making files smaller and better for privacy (your shooting location isn't leaked).
• On: metadata is preserved and files are slightly larger. Recommended for photography, or whenever you need to keep copyright or colour information.

This applies to PNG, JPEG, WebP, AVIF and HEIC.

Settings lets you switch between 19 languages: Follow System, 简体中文, 繁體中文, English, 日本語, 한국어, Français, Deutsch, Español, Italiano, Português (Brasil), Русский, Nederlands, Polski, Svenska, Dansk, Türkçe, العربية, Tiếng Việt. The interface updates immediately — no restart needed.

Three ways:

• The menu ImgZilla → Compare Images, shortcut ⌘D;
• The compare icon in the top-right of the start screen;
• The Compare button on any image in the list once it has finished compressing — it loads the original and the compressed version automatically (note: this button only appears when "Move originals to Trash" or a backup folder is enabled).

There are two slots: the left one is "before", the right one is "after". You can drop an image straight into an empty slot or click to choose one; a loaded slot can be swapped via "Choose again".

Once both images are loaded:

• Drag the divider in the middle left and right to compare the same area;
• Zoom with the + / - buttons in the toolbar, the "Actual Size" button, or your mouse wheel / trackpad pinch. The current zoom level is shown on the left of the toolbar;
• Drag the canvas to pan.

If both sides point to the same file, a note appears at the bottom of the window.

The free version compresses up to 10 images per day. Only successful compressions count against the quota — failures and images that are "already minimal" (can't be compressed further) don't use any.

The quota resets automatically every day (it refreshes across midnight even if the app stays in the background, so no restart is needed).

The current compression job pauses automatically (it isn't aborted) and the purchase panel opens. After a successful purchase, the paused job resumes automatically from where it stopped — you don't need to add the files again.

Click any "Remove limit" button to open the purchase panel. You have two options:

• Lifetime: a one-time purchase with no image limit, forever.
• Monthly subscription.

Prices are shown according to your App Store region.

Click Restore Purchases (available in both the purchase panel and Settings). If a previous purchase is detected, your access is restored automatically; if there is nothing to restore, you'll be told so.

It means the image didn't get meaningfully smaller (less than 0.4% reduction). ImgZilla keeps the original file untouched and doesn't use any of your free quota. Images that have already been optimised usually end up in this state.

The encoder couldn't process the file (it's corrupted, malformed, and so on). The original file is left unchanged and no free quota is used. Once everything finishes, a summary tells you how many failed.

By the way: ImgZilla reads the magic bytes in the file header to determine the real format, so a file named .png that is actually a JPEG still gets compressed correctly.

• Compare: opens the comparison window (only shown for successful compressions that have a backup);
• Reveal: shows the file in Finder;
• Remove: takes the image out of the compression list (the file itself is not deleted).

• First line: how many files have been processed, plus the overall percentage and size saved (savings under 1 KB aren't shown);
• Second line: the total number of files in the list and their total size.

A confirmation dialog appears ("Compression isn't finished — quit anyway?"). Choosing to quit aborts the job; images that were already compressed are unaffected.

No. Everything is processed 100% locally, and the app needs no network connection (apart from App Store purchase validation).

Use the menu Help → Feedback, which opens imagetool.app/ImgZilla.