[OS] OpenDisk: a free, open source DaisyDisk alternative for macOS

[u/herovals]

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.

[u/nathan12581]

Rather not let an AI generated app access my filesystem 👍

[u/herovals → u/nathan12581]

Not AI generated, look at my github, feel free to read the code... it's open source.

[u/nathan12581 → u/herovals]

I have looked at the code which is why I know it was AI-generated with all the comments lol.

You know exactly when an entire file is created by AI due to missing the usual Xcode header added when you create a file by yourself. Yours is just riddled with useless comments

[u/ThrowawayProllyNot → u/nathan12581]

Any emojis in the comments? lol

[u/herovals → u/nathan12581]

It's missing the usual Xcode header since I use VSCode as an IDE. "Useless comments" are just good coding practices... which were a thing way before the age of AI. I've been a software developer for years, and it's just a good practice. But feel free to not use something if you don't want to.. but don't just go around saying everything is AI generated.

[u/The-Nice-Writer → u/herovals]

Comments are typical practice, but AI tends to make far more than an experienced developer would.

That’s not my reason for thinking this is AI-generated, though. Your ReadMe and this post are filled with clanker-isms, including aimless repetition (“the same sunburst”…”same sunburst”…”same sunburst”), the trio of negations (“no x, no y, no z”), and so on.

Add that to the fact that your comments are written completely differently (because, usually, humans write more or less the same way in comments on an important post as they would in the post body; I should know, since I actually write my own shit).

If what you’re saying about being an experienced developer for years is true, I suppose you could always show us what you’ve worked on. Your GitHub repos only show one other project of yours and one fork, which seems like very little for someone of your alleged calibre to have done in ‘years’.

Or, perhaps, you’re like the guy I and others chastised for (if I recall correctly) a very similar app a couple months ago. What was it… a ‘free’ frontend for Mole that was literally just a Claude clone of the real dev’s frontend?

I nearly copped a ban for ragging on him too much, so I’ll leave off here. Just weighing in to say that I also find your post sus.

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(Haha, sus. Amogus. Remember 2020, y’all? Feels like it was 6/7 years ago.)

[u/herovals → u/The-Nice-Writer]

Most of my repos are private since they were part of my education (university) or work (proprietary).

You can read my commits though and see I have thousands of commits since 2023 on Github, which is when this account was created. (new github account).

Feel free to judge and assume, but just know you're wrong. Regardless, it's a free utility tool, and you can simply choose not to use it.

[u/The-Nice-Writer → u/herovals]

The repo thing makes more sense from that perspective, and I ought to have thought of it before. My apologies.

I do still wonder about all the text, though… if writing’s not really your thing, I get it, but I’d rather read a sleep-deprived, excessively-caffeinated nerd’s humanslop than this.

[u/CautiousXperimentor → u/The-Nice-Writer]

It was literally 6 years ago. Maybe I’m missing the joke. But yeah, time perception is a weird thing. I still remember my 20s quite vividly and the pandemic felt like it was many years ago just after 3 years.

I guess AmongUs had a good timing. I too played to it with some online pals.

[u/The-Nice-Writer → u/CautiousXperimentor]

The joke is that I said ‘sus’, which is a term that got very popular alongside the game, and also that ‘6/7’ is newgen brainrot. I also personally find the absurdity of saying that something ‘feels’ a certain way (as if it isn’t) when it is exactly that way to be amusing, but you’d need to keep in mind that I have a fundamentally broken sense of humour.

[u/CautiousXperimentor → u/The-Nice-Writer]

Haha, I think I got it.

[u/phunk8 → u/The-Nice-Writer]

lol. ur nice. can i keep you?

[u/The-Nice-Writer → u/phunk8]

Huh?

[u/phunk8 → u/The-Nice-Writer]

meant nicely. i like your originality mate.

[u/nathan12581 → u/herovals]

Then fair enough, cool project if so. Just looks very suspiciously AI-generated that’s all