DenseDrive
A compressed disk for macOS.
macOS can already compress files on disk. What it cannot do is keep them compressed: the moment a program writes to a file, that file is stored uncompressed again. For photos that does not matter. For a build cache, a dependency tree, a database dump or a VM image, the space you saved comes back over the following week.
DenseDrive puts the compression inside the file system instead, so every write is compressed as it happens and a rewritten file is compressed again. The disk shows up in Finder like any other and opens with a double click. It can also encrypt, which no other compressing option on macOS does — though it is a storage tool, not a security product.
What to expect
Measured, including the case where it does nothing for you.
node_modules, 14,885 files | 4.05× smaller |
| a working data folder | 3.38× smaller |
| installed games and video | 1.01× smaller |
That last row is not a typo. Media is already compressed and no compressor will change that — if your disk is full of video, photos, music and games, this is not the tool for you.
Get it on the Mac App Store
Free up to 8 GB, so you can measure it on your own data first.
If you would rather read how it is built than install it: notes from writing a file system on FSKit — the bug that corrupted other people’s data, the API contract I had not read, and the numbers, including the unflattering one.