Not sure what's taking up all that disk space on your Mac? Disk Wave is a free Mac app that scans your drive and shows you where the biggest files are.

Freeing up disk space can speed up your Mac, especially if your startup drive is almost full.

Disk Wave makes this important bit of system maintenance easier by showing you which folders hold the biggest files, helping you find large files you no longer need. This free download is a must for anyone who's just not sure where all that space went.

Finding those huge files

The first time you start up DiskWave you'll see your drives, and a few key folders, in the left panel.

diskwave-firstrun

Click any drive and the software will start scanning. You can explore your drive right away, but you will not see the size summaries until the scan is done. Don't feel like you need to stare at the window until it's done: a notification will alert you when an entire drive has been scanned.

Once everything's done you can really start digging. You'll see which folders are taking up the most space, and what the biggest files in those folders are:

diskwave-digging

Large files and folders will show up as red, meaning they'll stand out to you quickly. It's quite possible that a large file you forget existed is using up way more space than you have to spare. Finding them might be easier if you set this app to sort everything by size:

diskwave-sort

Do this and you can really get down to finding and deleting big files. Explore folders that seem bigger than necessary and you just might find a video file you forgot about three years ago. Check your app folder – you might find a massive game you don't play anymore taking up half a gig. You should also check your Library folder, because it's possible an app you deleted long ago left a bunch of useless files behind.

diskwave-sorted

Not sure what a given file actually is? Select the file, then use the Quicklook button – or simply press space – to see your Mac's summary of the file. You can also hit Cmd+I to display even more file information.

diskwave-quicklook

Images, videos and documents will even show a preview, giving you an exact idea of what's going on. You can also use the toolbar to directly delete a file from within the app, or open a given folder in Finder to check things out from there.

There are a few preferences for changing the way file size is calculated and the option to reveal hidden files:

diskwave-preferences

Overall the app is quite simple – and that's exactly how it should be. Scanning takes a while, but once that's done you can quickly explore your files and find out what's really taking up all of your space.

This app does one thing well, but are there other apps out there that do it better? Possibly.

Alternatives

If you like visualizations, the answer might be yes. Daisy Disk, for example, gives you this handy breakdown of all files on any drive:

That sort of visualization makes it even easier to find large files, though it's arguably harder to directly explore and delete files with this than DiskWave.

Daisy Disk sells for $20; DiskWave is free. If you want a free visual-based option, however, you're not out lof luck. Disk Inventory X offers you just that, and while it's not seen an update for a while it still works like a charm:

Still not content? Check out these three tools for analyzing your disk space, including the Finder, Disk Sweeper and Grand Perspective.

Conclusion

There are a lot of great apps for the job, but when it comes to finding large files I prefer Disk Wave's approach. Being able to find and delete files within a single user interface is nice, as is the integration with the Quick Look feature in OS X.

Of course, my opinion is far from the only one that matters. What do you think? Share in the comments below, because I'm sure plenty of people could learn from it.