# Purge on Mac Explained: purge, Purgeable Space, and Purge Apps

> Three unrelated things share the word purge on a Mac: APFS purgeable space, the purge memory command, and Purge apps including Mole's mo purge. Tell them apart before deleting.

Published: 2026-09-21 | Updated: 2026-09-23

The word "purge" points at three unrelated things on a Mac, and search results
mix all of them together. One is a storage number in Finder, one is a Terminal
command that touches memory, and one is a category of apps that promise to free
disk space. Deleting the wrong thing, or expecting the wrong result, almost
always starts with confusing these three.

This page sorts them out in one screen, then points to the deeper guide for each.
It uses "Mole" only for Mole for Mac at mole.fit and its own `mo` command line
tool.

## Three different purges (start here)

Match what you searched for to the row that describes it. Only one of the three
is a way to free disk space on demand, and it is not the one most people expect.

| What you typed | What it actually is | Does it free disk space? |
|---|---|---|
| purgeable space, purge storage | An APFS accounting category for files macOS can reclaim when it needs room | Not on demand; macOS decides |
| purge, sudo purge | A Terminal command that flushes disk-backed memory caches | No; it works on RAM, not your disk |
| Purge app, purge app mac, mo purge | Cleaner apps, and the Mole CLI command that removes rebuildable project files | Yes, but only files you can rebuild |

One sentence to decide: if you saw the word in Finder or Storage settings, read
the purgeable section; if you read it in a terminal recipe, read the command
section; if you are comparing tools, read the app section.

## If you searched for a "Purge" app

Results for "purge app mac" mix disk cleaners, memory utilities, and command
line tools, because all three borrowed the same word. That is why one list can
contain products that do completely different jobs.

A cleaner is worth trusting when it shows you the candidate list before it
deletes, not after. A blind "purge everything" button is the opposite of that:
it hides the one decision that matters. Mole treats the review as the product.
Clean and Analyze scan and show every candidate with its path and size,
scanning is free without a license, and you decide what to remove. There is no
race to a bigger number.

## The purge command (RAM), and what it does not do

`sudo purge` is a real macOS command that asks the kernel to flush disk-backed
memory caches. It needs administrator rights, and it works on memory, not on
your startup disk. It does not empty purgeable space in Finder, and it does not
delete files.

On a healthy Mac it is also rarely useful. macOS already manages that memory,
and the free RAM it appears to recover is usually filled again within seconds by
the same file cache that keeps a Mac fast. If your real question is whether you
need a memory cleaner, [that myth has its own
page](https://mole.fit/blog/do-you-need-a-mac-memory-cleaner).

## Purgeable space in Storage settings

Purgeable space is disk that macOS counts as available because it holds files it
can remove when something needs the room: local Time Machine snapshots, cached
downloads, and optimized-storage copies. It is a number, not a folder, and there
is no supported button to empty it on demand.

The full accounting, why Finder, `df`, and Storage settings disagree about one
volume, and what actually pools into that number, lives in [what is purgeable
space on Mac](https://mole.fit/blog/what-is-purgeable-space-on-mac). This page only separates it
from the other two purges.

## mo purge: clean project build artifacts (Mole CLI)

`mo purge` is a command in the free Mole CLI, not part of the Mac app. It scans
your project directories for build output you can regenerate and offers to
remove it. The scanned artifact types are `node_modules`, `target`, `.build`,
`build`, `dist`, and `venv`, under the default scan paths `~/Projects`,
`~/GitHub`, and `~/dev`. Projects touched in the last seven days are marked
Recent and left unselected.

Preview first, every time. Run it in dry-run mode, read the list, then run it
for real:

```
mo purge --dry-run
mo purge
```

`mo purge --dry-run` shows what it would remove without deleting anything, and
`mo purge --paths` configures which directories are scanned. Removed build
output is gone permanently, which is why the dry run matters: getting it back
means a rebuild or a reinstall of dependencies, and that may need the network.

This is a different job from a cleaner's cache sweep and from an IDE's own
"invalidate caches" step. If you are choosing between the terminal and the app,
the [Mole CLI or Mole for Mac](https://mole.fit/blog/mole-cli-vs-mac-app) comparison covers what
each one does. `mo purge` has no equivalent in the Mac app on purpose, because
the app deliberately drops what only the network can rebuild.

## Safe order of operations

1. Identify which purge you actually mean, using the table above.
2. Measure before you act: read the real number in Storage settings, in Activity
   Monitor's Memory tab, or with `du` for a folder.
3. Review the specific files, never a single total.
4. Act with the right tool, then confirm the free space changed.

For a broader disk cleanup that is not about the word "purge" at all, [how to
free up space on Mac](https://mole.fit/blog/how-to-free-up-space-on-mac) is the ordered
checklist, and [is Mole safe](https://mole.fit/blog/is-mole-safe) documents exactly what Mole
removes and what it refuses to touch.

## Further reading

- [What is purgeable space on Mac](https://mole.fit/blog/what-is-purgeable-space-on-mac): the
  APFS accounting behind the Storage number.
- [Mole CLI or Mole for Mac](https://mole.fit/blog/mole-cli-vs-mac-app): where `mo purge` fits
  and what only the app can do.
- [Do you need a Mac memory cleaner](https://mole.fit/blog/do-you-need-a-mac-memory-cleaner):
  why flushing RAM rarely helps.

## FAQ

### Is purge the same as purgeable space?

No. Purgeable space is an APFS storage number for files macOS can reclaim later.
`sudo purge` is a memory command. They share a root word and nothing else, and
neither one is a button that frees disk on demand.

### Will purge delete my photos or chat history?

`sudo purge` deletes nothing; it only flushes memory caches. Purgeable space
holds copies macOS can rebuild, such as snapshots and optimized-storage files,
not your originals. `mo purge` only removes rebuildable build artifacts in
project folders, and its dry run shows the list first.

### Does Mole need a license to scan?

No. Scanning and reviewing results are free in the Mac app, without a license
and without a time limit. A license is only required to act, and each paid tool
runs twice before asking. Mole for Mac is a one-time $19 purchase for two Macs,
with lifetime updates and a 14-day refund.

### Is the Mole CLI free?

Yes. The `mo` command line tool is free and open source under GPL-3.0,
installable with `brew install mole`. The paid app is a separate native
implementation and does not require the CLI.

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