How SiftMac decides what’s safe to delete

By Mohit Nippanikar, who makes SiftMac. These are the rules the app follows, written out so you can check them.

Most cleaners ask you to trust one big button. SiftMac asks one question of every item first: does it come back? The answer decides what happens to it, and you see the answer, with the reason, before anything moves.

The three verdicts

A fourth badge, In use, marks anything an open app is using. It’s never removed.

The Undo Shelf

• Anything that can’t come back on its own goes onto the Undo Shelf instead of being deleted: downloads, apps, duplicates, iPhone and iPad backups, the Trash, old AI chats, Mail and Messages attachments, old screenshots and leftovers of removed apps.
• It waits there for 7 days, or 14 or 30 if you choose in Settings. Put back returns each item to exactly where it was.
• After that, SiftMac’s small helper empties what has expired, even if you don’t open the app.

What SiftMac never touches

• Anything in use. Files an open app or running program is using are skipped, and checked again right before cleaning. A cache folder counts as in use when its app is open.
• Your never-touch list. Add any folder in Settings and nothing in it, or containing it, is ever listed.
• Apple’s own caches (com.apple.… and a few system ones). The system often guards them, and clearing them buys little.
• Inside the Photos library. Duplicates and similar photos are found among your files, never inside Photos.
• The language files inside apps. Removing them breaks app updates and code signatures.
• Apple Intelligence models, Time Machine local snapshots and Docker’s disk image. SiftMac explains how much space they take and why; macOS and Docker manage them.
• Docker volumes. They hold databases and other data. Docker’s images and build cache are cleared only through Docker’s own prune commands.
• Claude Code’s memory folder and your projects’ own files. Old chats are listed only after 7, 30 or 90 days (you choose), and never anything from the last day.
• AI apps’ caches while the app is open. Claude, Cursor, Windsurf, Antigravity and Codex caches are cleared only when that app is closed.
• Downloaded models you might still use. Hugging Face, LM Studio and Ollama models are always “You decide”, and an Ollama layer shared with another model isn’t counted.

What it waits for before listing something

• Logs newer than 7 days stay: something may still be writing them.
• Leftovers of removed apps are listed only when nothing from that maker is installed, nothing running matches, and nothing in them changed for 2 weeks.
• Installers and archives in Downloads are listed only once they’ve done their job: the app is installed or the archive is unpacked, or you opened it more than a week ago. Anything never opened is left alone.
• Build folders are listed only in projects you haven’t changed for 3 months.

Honest numbers, and nothing leaves your Mac

• Only space you really get back is counted. APFS clones and hard links share their space, so removing one copy frees nothing, and SiftMac doesn’t pretend it does.
• Apps an administrator installed are removed through macOS’s own password dialog. SiftMac never sees the password.
• No account, and no file names or paths ever leave your Mac. SiftMac goes online only to check for updates and to check your licence.

Try the rules yourself

The “Does it come back?” checker runs the same notes the app uses, in your browser: paste any folder from your Mac and see its verdict and why. Nothing is uploaded. For specific folders, see what’s safe to delete on a Mac.