I have a Samsung Galaxy A03 on my desk with 32GB of storage and about 31GB of it gone. I need the phone for a project, but right now, it can barely install anything.
I could fix this with a factory reset in 10 minutes. However, it would wipe every app already on it, along with all my local data, and setting those back up is the work I was trying to avoid.
I went through the usual route using the file system analyzer to find files I could delete, and discovered something interesting.
My photos, documents, videos, and system files used up less than 10GB. WhatsApp took an additional 2GB, so where did the rest of the storage go?
I needed to get to the bottom of this, since my phone had to get lighter without losing anything, and that’s not what app bloat usually allows.
After manually deleting as much as I could, I decided to try a storage cleaner. I only looked at open source apps because I have a phone I couldn’t reset. I wanted to check what a tool claims against what it does.
Why the usual advice didn’t work here
Every fix cost me something I needed
One UI Core’s storage screen gives you three suggestions: uninstall unused apps, clear app cache, or delete large files.
However, all three take something away. On a 32GB phone, the apps are the storage, and the reason I hadn’t reset the phone in the first place.
The microSD slot doesn’t help either. The card takes photos, video, and downloads, but app data and caches stay on internal storage, and that’s what was filled up.
What I needed was space that didn’t belong to anything. That’s a much smaller category, and nothing in Settings actually looks for it.
The analyzers only found what I couldn’t delete
Where Disky and DiskUsage both stopped
I tried Disky, and it’s only available on F-Droid. It scans fast and splits storage by directory with apps included. Within a minute, I had a clean ranked list of my biggest folders.
The biggest folders were sorted by size, making them easy to spot. But they belonged to the apps I didn’t want to remove.
DiskUsage gave me the same answer through an older interface. Its treemap is still a good way to read a filesystem, but its last F-Droid release is a 5.0 alpha from December 2023.
Both did their job correctly, but they don’t tell you the files that have been abandoned, which was the only question that mattered to me.
On the other hand, Cache Cleaner is still listed on F-Droid. Its description says the developer stopped maintaining it because Android 6.0 and later made it unnecessary.
Android 16’s built-in tools are good for anyone on a current phone, but the A03 ended at Android 13, so it never got them.
SD Maid found the only space that was free to take
Why Android can’t see this junk on its own
When you uninstall an app, Android deletes its sandboxed directories. However, anything the app stored outside those locations stays exactly where it is.
This is especially annoying because apps create folders in the internal storage under names that don’t identify them. The hidden OBB folder is a good example.
Android doesn’t clean it because it doesn’t track it. The system keeps no record of connecting a stray folder to a package removed two years ago.
SD Maid 2/SE works because it carries its own reference data mapping folder names to the apps that create them. Scanning is easy, but the mapping is the actual product.
CorpseFinder listed every result next to the app it came from, including a few I’d installed once, uninstalled, and forgotten. It came to about 3GB.
On 32GB, that amount is the difference between a phone that can install things and one that can’t.
Where the remaining space came from
SystemCleaner cleared empty folders and old log files. That freed very little on its own but made the file manager readable again.
AppCleaner produced the rest. It clears hidden caches, and on modern Android it does that by using the accessibility service to tap the clear cache button in Settings for each app in turn.
That’s the same permission the ad-driven cleaners ask for, and it’s fair to be uneasy about it. The listing states the API is not used to collect information, and the app is open source on GitHub, so you can check that claim.
The bulk automation is available on the Pro tier. There are no ads, and the upgrade is a one-time purchase.
Scanning took five minutes on a chip with 4GB of RAM, and every tool lets you review results before anything is deleted.
Problem solved
The A03 has around 5GB back and enough room to run the project I intended for it, and I didn’t have to uninstall a single app.
What’s interesting about this exercise is that the files I cleared had no owner, and every analyzer I tried could see those folders without any idea of what they were.
SD Maid 2/SE’s free build is available on F-Droid, so anyone going that route should watch what Google’s new sideloading rules break, because getting it may not be this simple anymore.
