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What is lulu?

objective-see/lulu — explained in plain English

Analysis updated 2026-06-24

★ 12,568Objective-CAudience · ops devopsComplexity · 2/5Setup · easy

In one sentence

LuLu is a free, open-source firewall for Mac that lets you monitor and block which apps on your computer can connect to the internet or other networks.

Mindmap

mindmap
  root((repo))
    What It Does
      macOS firewall
      Outbound connection control
      Network traffic monitor
    Audience
      Privacy-conscious Mac users
      Security professionals
    Key Features
      App-level blocking
      Connection alerts
    Resources
      Objective-See docs site
      Patreon support page
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Code map

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filefunction / class

What do people build with it?

USE CASE 1

Block a specific app from making unauthorized outbound internet connections on your Mac.

USE CASE 2

Monitor which processes on your Mac are sending data to external servers.

USE CASE 3

Audit outbound network traffic to detect unexpected or suspicious app behavior.

What is it built with?

Objective-CmacOS

How does it compare?

objective-see/lulusvprogresshud/svprogresshudrobbiehanson/cocoaasyncsocket
Stars12,56812,46212,454
LanguageObjective-CObjective-CObjective-C
Setup difficultyeasyeasymoderate
Complexity2/52/53/5
Audienceops devopsdeveloperdeveloper

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

How do you get it running?

Difficulty · easy Time to first run · 30min

So what is it?

LuLu is a free, open-source firewall for Mac computers. A firewall watches the connections your computer tries to make to the internet or other networks, and LuLu is built specifically for macOS. The repository's README is brief: it names the product, links to the full documentation on the developer's website (objective-see.com), and includes a link to a Patreon page for those who want to support its development financially. The source code itself is here, but the detailed usage instructions live on the external documentation page. Objective-See is a well-known name in Mac security tooling. LuLu fits that pattern: it is a security-focused utility for people who want to monitor and control outbound network connections from their Mac. Beyond that description, the README does not provide additional technical or functional detail.

Copy-paste prompts

Prompt 1
How do I use LuLu to block a specific app from accessing the internet on my Mac without affecting other apps?
Prompt 2
Write a setup guide for configuring LuLu on a new Mac to allow only essential system services to phone home.
Prompt 3
What LuLu rules should I create to stop browser extensions from making background network requests?
Prompt 4
How do I build LuLu from the objective-see/lulu source code on macOS using Xcode?

Frequently asked questions

What is lulu?

LuLu is a free, open-source firewall for Mac that lets you monitor and block which apps on your computer can connect to the internet or other networks.

What language is lulu written in?

Mainly Objective-C. The stack also includes Objective-C, macOS.

How hard is lulu to set up?

Setup difficulty is rated easy, with roughly 30min to a first successful run.

Who is lulu for?

Mainly ops devops.

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