Mac Outbound Firewalls Compared: NetBlocker, LuLu, Radio Silence and Little Snitch

The short answer: choose the workflow, not just the feature count

There is no single best outbound firewall for every Mac user because these products optimize for different jobs. NetBlocker keeps the decision at app level: choose what should stay offline and see the relevant components grouped under that app. Other products put more emphasis on individual connections, a whole-Mac activity view, or granular network policy.

NetBlocker provides an app-centred drag-and-drop workflow for €4.99. LuLu provides free, open-source rules and connection decisions. Radio Silence pairs a quiet blocklist with a system-wide real-time monitor. Little Snitch focuses on detailed network analysis and highly configurable rules. More information is useful when you need to investigate traffic, but it is not automatically a better fit when the goal is simply to keep selected apps offline.

Features and purchase terms at a glance

Why the built-in macOS firewall is not in the table

Apple describes the macOS firewall in terms of protecting the Mac from network access, controlling incoming connections, allowing signed software to receive connections, and resisting probing. It does not provide the same per-app outgoing decision workflow as the four products above.

That does not make it useless. It means it addresses a different direction of traffic. You can keep the built-in firewall enabled while deciding whether you also need control over connections initiated by apps on your Mac. Read Apple’s firewall security documentation for its current behavior.

Choose NetBlocker for fast, app-centred control

NetBlocker suits the question, “Which apps should stay offline?” Drag an app from Finder, turn on protection, and inspect its main process, embedded helpers, XPC services, and confidently associated processes in the same entry. It does not ask you to approve each destination or make you search a whole-Mac connection feed for the app you just selected.

That focus keeps the interface calm and makes NetBlocker the lowest-priced paid product in this comparison at €4.99. It is not intended for endpoint or port rules, long-term traffic analysis, or Intel Macs. It requires Apple silicon and macOS 13 or later; a paid license needs periodic validation with a 14-day offline allowance. The seven-day trial lets you test the actual apps that matter to you.

For the exact steps and verification caveats, read how to block internet access for a Mac app.

Choose LuLu for free, open-source outbound control

LuLu is free, open source, supports macOS 10.15 and later, and can alert when an unknown process attempts an outgoing connection. It supports manually managed rules, operating modes, and allow or block lists for endpoints. Objective-See also provides the Netiquette network monitor.

Choose it when open source, zero cost, or hands-on rule control is central to your decision. Choose NetBlocker when you prefer to start from a deliberate app list, keep related processes grouped under each app, and avoid a per-connection approval workflow. Our NetBlocker vs LuLu comparison goes into that trade-off in more detail.

Choose Radio Silence for a system-wide connection view

Radio Silence combines a no-pop-up blocking workflow with a monitor showing current connections across the Mac. Its published features include helper apps, background processes, daemons, XPC services, and automatic blocking of child processes belonging to blocked apps.

That system-wide view is useful when watching all current connections is part of your workflow. NetBlocker takes a different approach: it keeps attention on the apps you deliberately blocked and presents their associated components in context, without turning the main experience into a whole-Mac monitor. NetBlocker costs €4.99; Radio Silence costs US$9 and also supports Intel Macs and macOS versions from 10.15. See the detailed NetBlocker vs Radio Silence comparison.

Choose Little Snitch when granular analysis is the goal

Little Snitch can decide by app, server, domain, port, or protocol; organize profiles and rule groups; use blocklists; and retain network activity for later analysis. It also offers Silent Mode when immediate connection alerts would be disruptive.

Those tools serve a different job and are not automatically an advantage for someone who only wants selected apps to stay offline. Little Snitch has a US$59 single-license price and a correspondingly larger interface; NetBlocker costs €4.99 and keeps the workflow at app level. The current Little Snitch 6 supports macOS 14 and later, while its developer provides older compatible versions for some earlier macOS releases.

How this comparison was prepared

This page is written by NetBlocker’s developer and is not an independent review. It compares published capabilities and purchase terms, not blocking reliability, CPU use, battery impact, or the number of helpers detected. It does not claim that one product blocks more reliably or efficiently than another.

Details were checked on 20 September 2026 against the official pages for LuLu, Radio Silence, Little Snitch, its current shop, and Apple’s macOS firewall. Test your own apps, read each product’s current documentation, and avoid assuming that a saved rule proves every existing connection has ended.