u/herovals

How does this even happen after a few months… Meepo Voyager.

Video of the break

I've been working on OpenDisk, an open source app that shows what's taking up space on your Mac and lets you clear it out.

What it does:

• Scans a 1 TB drive in about 17 seconds. DaisyDisk took 37 on the same machine.
• Rescans in a couple of seconds, because it only looks at folders that changed since the last scan.
• Shows purgeable space and caches, so the totals match what macOS reports.
• Lets you drag files into a "Collector", see how much space you'll get back, and delete them all at once.

There are no accounts or analytics. The only network request is the update check, and you can confirm that in the code.

You can install it with brew install --cask opendisk, download it from opendisk.app, or get it from the Mac App Store.

Contributions are welcome. Bug reports and feature ideas are just as useful as PRs.

GitHub: https://github.com/137137137/OpenDisk

The problem

When a Mac runs low on space, System Settings shows a colored bar and a "System Data" blob that explains nothing. Finding the actual 40 GB folder means walking the filesystem yourself or paying for a tool. DaisyDisk has been the standard for years. It costs $9.99 and the source is closed.

What OpenDisk does

OpenDisk maps your drive as an interactive sunburst chart. It scans a full disk in seconds and streams results in as it goes, so you can start clicking around before the scan finishes. Hover a slice for its exact size. Click to zoom into a folder. Use the folder list and breadcrumbs to step back out. Drag anything into the collector, check the reclaimed total, and delete in one action.

Also:

• Incremental rescans replay filesystem events, so a repeat scan runs 20 to 28x faster than a cold one.
• Handles APFS volume groups, firmlinks, snapshots and purgeable space. The total matches what macOS reports as used.
• Purgeable space breakdown shows which caches are reclaimable.
• Instant search across the whole scanned tree, including drives with millions of files.
• External drives show up automatically when you plug them in.

Some of this came from feedback on Reddit. File preview was one of those requests. Thanks u/MrBiz.

Compared to DaisyDisk

OpenDisk is free, MIT licensed, and faster. On a cold scan of a 1 TB Apple Silicon volume, OpenDisk finished in 17s and DaisyDisk took 37s. The app is under 2.5 MB because it's native Swift with nothing bundled.

The full source is on GitHub, so you can read what it does before giving it disk access:

https://github.com/137137137/OpenDisk

Pricing

Free. MIT licensed. No in-app purchases, no accounts, no telemetry.

• Direct download: https://opendisk.app/
• Source: https://github.com/137137137/OpenDisk
• Mac App Store: https://opendisk.app/appstore

Requires macOS 26 (Tahoe) or later, Apple Silicon or Intel. It asks for Full Disk Access on first launch. Without it, macOS hides parts of the filesystem and the totals come up short.

I'm the developer. Questions and bug reports are welcome here or in GitHub issues.

Problem

When your Mac runs low on space, System Settings gives you a colored bar and a "System Data" blob that explains nothing. Finding the actual 40 GB folder means walking the filesystem yourself or paying for a tool that does it. DaisyDisk has been the go-to for that for years, but it costs $9.99 and you can't see what it's doing.

OpenDisk does the same job. It maps your drive as an interactive sunburst chart, scans a full disk in seconds, and streams results in live so you can start clicking around before the scan finishes. Hover a slice for its exact size, click to zoom into that folder, use the folder list and breadcrumbs to step back out.

Drag things into the collector to delete them, and free up your disk space!

Other things it does:

• Incremental rescans replay filesystem events instead of starting over, so a repeat scan runs 20 to 28x faster than a cold one.
• Handles APFS volume groups, firmlinks, snapshots and purgeable space, so the total actually matches what your Mac reports as used.
• Purgeable space breakdown, so you can see which caches are reclaimable.
• Instant search across the whole scanned tree, usable on drives with millions of files.
• Collector: drag files in from anywhere in the app, check the reclaimed total, delete in one action.
• External drives show up automatically when you plug them in.

Comparison

DaisyDisk ($9.99) is the closest comparison. Same sunburst interaction, and OpenDisk is free, MIT licensed, and faster. On a cold scan of a 1 TB Apple Silicon volume, OpenDisk finished in 17s and DaisyDisk took 37s. The app is also under 2.5 MB, because it's native Swift with nothing bundled into it.

The full source is on GitHub if you want to read what it's doing before you give it disk access: https://github.com/137137137/OpenDisk

Pricing

Free, MIT licensed, no in-app purchases, no accounts, no telemetry.

• Mac App Store: https://apps.apple.com/us/app/opendisk/id6793260558
• Direct download: https://opendisk.app/
• Source: https://github.com/137137137/OpenDisk

Requires macOS 26 (Tahoe) or later, Apple Silicon or Intel. It asks for Full Disk Access on first launch, otherwise macOS hides parts of the filesystem and the totals come up short.

I'm the developer. Happy to answer questions or take bug reports here or in GitHub issues.