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Spillway

See where your Mac’s space goes, get a warning before it fills up and safely free what can be rebuilt.

Download for macOS Support the project

Signed and notarized by Apple Version 1.3.0 macOS 14 or later

What it does

  • Explains every gigabyte

    What takes up space, which app it belongs to and what happens if you delete it.

  • Warns you before it fills up

    Checks your disk every few minutes, estimates when it would fill up and warns you in time, even when the app is closed.

  • Frees space safely

    Finds caches and files that can be rebuilt. Nothing is deleted until you review it.

  • Finds what weighs the most

    Large files and duplicates, so you decide what to keep.

Warnings by level

Spillway measures your disk’s free space and tells you which level you are at.

  • Good

    More than 25 GB free

    Your Mac has plenty of room.

  • Watch

    10 to 25 GB

    Worth checking what is growing.

  • Low

    5 to 10 GB

    Free up space soon.

  • Red

    Less than 5 GB

    Apps may start to fail: free up space now.

You can adjust the thresholds in the app. On large disks, each level also takes a percentage of the disk into account, so the warning arrives in time.

Cleans up without risk

Everything it finds is grouped by how safe it is to delete.

  • Safe

    Caches that apps rebuild on their own. They are deleted directly, because moving them to the Trash frees nothing.

  • Ask

    Things you might want to keep. It asks you and moves them to the Trash.

  • Report only

    What only you can decide. It tells you how much space it takes, but leaves it alone.

  • It never deletes anything you haven’t reviewed.
  • It never touches anything in use: if the owning app is open, it leaves it.
  • It never touches your photos, your mail, your messages or your keys.
  • When it finishes, it measures on disk how much space was really freed.

If you code

Spillway recognizes the caches and build files of your tools and, when there is one, shows you the official command to clean them.

  • Xcode and simulators
  • JavaScript (npm, pnpm, Yarn)
  • Python
  • Rust
  • Go
  • Java and Gradle
  • Homebrew
  • Docker
  • AI agents and local models

Command-line tool

For your scripts and your agents:

spillway status --json
Free space, level and forecast.
spillway clean --safe
Cleans only the safe items you turned on.

Requirements

  • macOS 14 or later.
  • Full Disk Access, to measure folders like Mail or iCloud Drive. Without it, it works in partial mode and tells you what it could not check.
  • Notification permission, to warn you in time.

Installation

  1. Download the file and open it.
  2. Drag Spillway to the Applications folder.
  3. Open it and follow the welcome screen: that is where you grant the permissions.

Your information stays on your Mac

  • No accounts and no telemetry: nothing leaves your Mac.
  • It measures your files by their size. It only opens one to compare duplicates, and only when you ask it to.
  • It never asks for your password.
  • It never downloads your iCloud files to measure them.

Support the project

Spillway is free and will stay free. Your support helps us keep it up to date and add new features.

Support the project

What’s new

  1. 1.3.0 Latest

    Spillway signed and notarized, and it now also frees up what you keep in iCloud Drive

    See changes

    New

    • Removes the local download of iCloud Drive files that are already in the cloud: you free up space and they stay available in iCloud and on your other devices.
    • You can support the project with whatever you like from Home and About; Spillway is still free.

    Improved

    • Spillway is signed and notarized by Apple: it installs without security warnings.
    • Works the same on Macs with Apple silicon and with Intel.

    Fixed

    • The background helper recovers on its own if an update leaves it stopped.