explaingit

dizzpy/boo

Analysis updated 2026-05-18

4SwiftAudience · generalComplexity · 2/5LicenseSetup · easy

TLDR

A tiny native macOS menu bar app that automatically sorts files out of your Downloads folder by type and asks where to put unknown file types, with an animated ghost icon.

Mindmap

mindmap
  root((Boo))
    What it does
      Watches Downloads folder
      Auto-sorts by file type
      Learns from user answers
    Interface
      Menu bar ghost icon
      Animated moods
      Toast notifications
    Privacy
      No network code
      App Sandbox only
    Customize
      File type rules
      Ghost SVG art
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Code map

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What do people build with it?

USE CASE 1

Keep your Downloads folder automatically organized by file type without any manual dragging.

USE CASE 2

Teach the app where a new file type belongs so it never piles up in Downloads again.

USE CASE 3

Get a menu bar notification each time a file is moved after downloading.

USE CASE 4

Customize file-type routing rules in source code to match your personal folder structure.

What is it built with?

SwiftmacOSApp Sandbox

How does it compare?

dizzpy/booaydahnizzy/calendar-drag-interactionheyitsbarish/nomad-classic
Stars444
LanguageSwiftSwiftSwift
Setup difficultyeasyeasymoderate
Complexity2/52/53/5
Audiencegeneraldeveloperops devops

Figures from each repo's GitHub metadata at analysis time.

How do you get it running?

Difficulty · easy Time to first run · 5min

Not notarized, requires a one-time 'Open Anyway' approval in macOS System Settings on first launch.

Use freely for any purpose, including commercial use, as long as you keep the copyright notice.

In plain English

Boo is a small macOS menu bar app that watches your Downloads folder and automatically moves files into organized folders. When you download something it recognizes, a little ghost icon in your menu bar animates to show it eating the file and moves it to the appropriate folder, such as Images, Archives, or Documents. For file types it has never seen before, it shows a confused expression and asks you where that type of file should go, then remembers your answer for future downloads. The app is built as a native Swift application with no web technologies or heavy runtimes underneath it, which keeps it small at a couple of megabytes. It runs in the background and only watches the Downloads folder, it never touches any other part of your filesystem. The ghost icon changes expression depending on what it is doing: watching, eating, confused, napping, or happy. There is also a toast notification system that briefly shows a message like "Nom! Saved to Images" when a file gets sorted. Settings let you pause the sorting, turn toast notifications on or off, and review or change the rules you have taught it for unknown file types. Boo has no network code at all. It cannot upload files, send analytics, or check for updates in the background. The only connection to the outside world is a menu item that opens your browser to the GitHub releases page so you can manually check for new versions. It runs in the macOS App Sandbox, which means the operating system itself limits what the app can access to just the Downloads folder. The app is not notarized (which requires a paid Apple Developer account), so macOS will initially block it as an unidentified developer app. The README explains how to approve it through System Settings. SHA-256 checksums are provided for each release so you can verify the download before running it. File-type sorting rules and the ghost's SVG artwork can both be customized by editing the source code. The project is MIT-licensed.

Copy-paste prompts

Prompt 1
I want Boo to send .epub files to a Books folder. Show me what to edit in Categories.swift to add that rule.
Prompt 2
Walk me through approving Boo on macOS when it shows the unidentified developer warning in System Settings.
Prompt 3
How do I make Boo start automatically each time my Mac boots?
Prompt 4
I want to replace Boo's ghost SVG with a custom icon. Which file do I edit and what format does it need to be in?
Prompt 5
Explain how Boo's App Sandbox entitlement works and what parts of my filesystem it can and cannot access.

Frequently asked questions

What is boo?

A tiny native macOS menu bar app that automatically sorts files out of your Downloads folder by type and asks where to put unknown file types, with an animated ghost icon.

What language is boo written in?

Mainly Swift. The stack also includes Swift, macOS, App Sandbox.

What license does boo use?

Use freely for any purpose, including commercial use, as long as you keep the copyright notice.

How hard is boo to set up?

Setup difficulty is rated easy, with roughly 5min to a first successful run.

Who is boo for?

Mainly general.

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