This is a comparison written by a vendor, so let us set the terms first. HisnLabs makes FireAI, one of the five tools below. Every fact about a competitor here comes from that competitor’s own website, linked in the sources, and where another tool is the better choice for a given reader we say so. The goal is not to win the table; it is to leave you with an outbound firewall on your Mac, whichever one it is, because the one thing all five vendors agree on is that macOS does not filter outgoing connections on its own.
What we compared, and what we left out
The tools here are firewalls: software that decides which connections an app may open. We compare them on six things that decide daily use: outbound control, per-app rules, whether rules are tied to an app’s code signature, threat-intelligence feeds, on-device AI review, and the price model. We deliberately left antivirus out of the table. A firewall and a file scanner do different jobs, none of these five scans files, and if you want a scanner the right place to compare them is an independent lab such as the AV-TEST Institute, which publishes macOS results across protection, performance and usability.
Apple’s built-in firewall
Every Mac ships with a firewall under System Settings, Network, Firewall, and Apple’s User Guide describes its purpose as blocking “unwanted contact initiated by other computers”. Apple’s Platform Security guide lists the controls: block all incoming connections, automatically allow built-in and signed software to accept incoming connections, allow or deny incoming access per app, and a stealth mode that ignores ICMP probes and port scans. It is free, it is already installed, and you should turn it on. It also has no outbound control at all, no rules by domain or port, no feeds and no AI. It is the baseline, not a competitor to the rest, and every tool below assumes it is on.
Little Snitch
Little Snitch, from Objective Development, is the reference product in this category and the one most of the others are measured against. Its product page describes monitoring of both outbound and inbound connections with prompts to allow or deny, rules per app that can be narrowed to servers, domains, ports and protocols, and what the company calls cryptographic process identification: rules are bound to an app’s code signature, so they survive the app being moved and do not transfer to an impostor. It adds curated blocklists updated daily, including IP-based lists, a Network Monitor with traffic history of up to twelve months organised by app, domain or country, a Silent Mode that allows everything and lets you review later, rule groups with automatic profile switching per Wi-Fi network, DNS encryption and a command-line tool.
The download page lists the current release, 6.5, as running on the newest macOS and also on macOS Tahoe, Sequoia and Sonoma. Those older systems still ship on Intel Macs, so if you are on Intel hardware, check the download page for your model; it is one of the strongest reasons to choose Little Snitch today. It is a paid, one-time licence sold from Objective Development’s store, with a 30-day trial and a demo mode that runs in restartable three-hour sessions. There is also Little Snitch Mini on the Mac App Store, whose monitoring, connection list and map are free while blocking is unlocked by an in-app purchase. What Little Snitch does not have is an AI reviewer for unknown apps: its answer to the prompt problem is Silent Mode plus your own judgement, which for an experienced user is a perfectly good answer.
LuLu
LuLu is Objective-See’s firewall, and its two defining facts are on its product page: it is free, and it is open source, released under the GPL-3.0 licence on GitHub. It blocks unknown outgoing connections and prompts you, rules are per process and can be scoped to the whole program or a specific remote endpoint and given a duration, it verifies code signing to confirm a program is what it claims to be, and it integrates VirusTotal lookups. It requires macOS 10.15 or later, which means it runs on Intel Macs as well as Apple silicon, and, like every modern Mac firewall, it asks you to approve its system extension and network filter at install time.
Its limits are stated with unusual candour on the same page. LuLu only monitors outgoing traffic, and blocking by hostname works only for apps that use Apple’s Network.framework or NSURLSession; a browser such as Chrome can be blocked only by IP address, not by hostname. There are no curated threat feeds and no AI. For someone who wants to read the code they are trusting, or who will not pay for a firewall, LuLu is the honest recommendation, and its author’s other free tools, KnockKnock and BlockBlock among them, are worth installing alongside it.
Radio Silence
Radio Silence takes the opposite design position from a prompting firewall. Its site describes per-app blocking of outgoing connections with no pop-ups at all: you pick an app, it goes silent on the network, and local process communication keeps working. A Network Monitor shows live connections including the helper apps, background daemons and XPC services most people do not know they are running. It costs $9 as a one-time purchase with a free trial and a 30-day money-back guarantee, requires macOS 10.15 or newer, and runs on Intel and Apple silicon Macs alike.
What you give up is granularity. Radio Silence blocks an app or does not; there are no rules by domain, host or port, no code-signature-bound rules described on the site, no threat feeds and no AI. If your goal is “this app should never touch the internet” and nothing more, it is the simplest and cheapest way to get there.
FireAI
FireAI, from HisnLabs, is the newest of the five and the only one built around an on-device reviewer. Its per-app rules allow or deny by host, domain, IP or port and follow the app’s code signature. Permission prompts ask before an unknown app connects. With the optional model installed, a download of about 1.5 GB, a built-in reviewer examines connections from apps that have no rule yet, blocks or flags suspicious ones and shows its reason in the prompt; every AI decision becomes a visible rule you can undo, and nothing about your traffic leaves the Mac. Threat feeds from abuse.ch, Spamhaus, Phishing Army, OpenPhish, the Tor exit node list and FireHOL can be applied locally as system-wide IP blocklists. Around that sit four security modes (Home, Coffee shop, Paranoid, Under attack; the stricter ones also block telemetry, trackers and unsigned apps), a kill switch that cuts internet while keeping the local network, an unencrypted data guard that stops card numbers, passwords and API keys leaving over plain HTTP, plain-language orders in English or French such as “block Microsoft Teams”, a live 3D map of connections with blocked ones in red, and rule files you can export and import as text.
The limits are just as concrete. FireAI requires macOS 14 or later on Apple silicon; there is no Intel build yet, though one is planned. It is paid: €49, $49 or £49 as a one-time purchase, or €6 per Mac per month billed yearly for businesses. It is a far younger product than Little Snitch, and it has no central admin console or MDM guide yet; rule files are how a small team shares a setup today. And, like the other four, it is a firewall only: it does not scan files, analyse processes in memory, remove anything from disk or decrypt anything.
Side by side
- Outbound control: Apple’s firewall, none. Little Snitch, yes, plus inbound. LuLu, yes, outbound only. Radio Silence, yes, per app on or off. FireAI, yes.
- Per-app rules by host, domain or port: Apple, no (incoming per app only). Little Snitch, yes. LuLu, per process and per endpoint, with the hostname caveat for apps outside Apple’s networking frameworks. Radio Silence, no, whole app only. FireAI, yes.
- Rules bound to code signature: Apple, signed apps can be auto-allowed inbound. Little Snitch, yes. LuLu, code-signing verification, yes. Radio Silence, not described. FireAI, yes.
- Threat-intelligence feeds: Apple, no. Little Snitch, curated blocklists updated daily. LuLu, no, though it offers VirusTotal lookups. Radio Silence, no. FireAI, yes, six public feeds applied locally.
- On-device AI review of unknown apps: Apple, no. Little Snitch, no. LuLu, no. Radio Silence, no. FireAI, yes, optional.
- Price model: Apple, free and built in. Little Snitch, one-time paid licence with a 30-day trial; Little Snitch Mini free for monitoring. LuLu, free and open source. Radio Silence, $9 one-time. FireAI, €49 one-time or €6 per Mac per month for business.
- Intel Macs: Apple, yes. Little Snitch, check the download page for your model. LuLu, yes (macOS 10.15+). Radio Silence, yes. FireAI, not yet.
Which one fits you
If you have an Intel Mac, the choice is between Little Snitch, LuLu and Radio Silence, and FireAI is not an option until the Intel version ships. If you will not pay, or you want to audit the code, LuLu. If you want the deepest rule engine, the longest history and a product that has been refined for many years, Little Snitch; experienced users who like writing precise rules tend to stay there. If you want one specific app cut off and no dialogs, Radio Silence at $9 is hard to argue with.
FireAI makes sense for a specific reader: someone on an Apple silicon Mac who wants outbound control and per-app rules but does not want to be the one adjudicating every prompt from an app they just installed, and who cares that the reviewer doing that work runs locally and can be overruled. It also suits small businesses that want threat feeds, the unencrypted data guard and a rule file they can copy to each Mac, with the caveat that central management is still on the roadmap. Whichever you choose, turn on Apple’s inbound firewall as well; none of the four third-party tools replaces it, and the combination is what closes both directions.
How FireAI and HisnLabs fit in
FireAI is the newest tool in this comparison and the only one with an on-device reviewer; it is also Apple silicon only and paid, and if either of those rules it out for you, Little Snitch, LuLu and Radio Silence are all good answers we would rather you pick than go without an outbound firewall.
FireAI is HisnLabs’ own product: an on-device AI firewall for Mac. It shows every connection your apps make, in plain language, and lets you decide what leaves your Mac — its AI runs locally, so your traffic is never sent to us or anyone else. HisnLabs’ security research team is the group that keeps that decision-making accurate: cataloguing which domains are ordinary telemetry versus a real product, tracking the country and network behind a connection, and training the on-device model (its Autopilot feature) on real traffic patterns, all without any of it leaving your Mac.
You can read the technical decisions behind it, or try FireAI for 17 days, at FireAI, by HisnLabs.