Little Snitch 4 is using a Network Kernel Extension to perform its network filtering. Apple has discontinued the support for this type of kernel extensions in macOS Big Sur. The system therefore refuses to load the unsupported extension.

Starting with version 5, Little Snitch is therefore using the Network Extension technology instead, which is fully compatible with macOS Big Sur and later.

No, Little Snitch 5 cannot be used on macOS Catalina. It requires macOS Big Sur or later. If you want to use Little Snitch on Catalina, you have to install version 4 instead.

→ Download Little Snitch 4

Background

Starting with version 5, Little Snitch is therefore using Apple’s Network Extension framework, which replaces the previous kernel extension API, that is no longer supported on macOS Big Sur.

Just buy a license for Little Snitch 6. This license is also valid for Little Snitch 5.

Yes, your existing rules from Little Snitch 4 will be preserved.

Little Snitch 4 should not be uninstalled prior to upgrading to macOS Big Sur to preserve your rules and your registration information.

We seek to ensure that latest version of Little Snitch is always compatible with the latest versions of macOS (typically including at least one or two of the previous major versions).

The only exception may be the period immediately after a new major macOS release, during which it may be necessary to make adjustments to Little Snitch and provide them in the form of an update.

For older versions of macOS we provide compatible downloads of previous Little Snitch versions.

→ Download the latest version of Little Snitch
→ Download previous versions of Little Snitch

Here is an overview of the latest Little Snitch versions available for each macOS Version:

macOS 15 (Sequoia)
Little Snitch 6 (current version)
Little Snitch 5.8

macOS 14 (Sonoma)
Little Snitch 6 (current version)
Little Snitch 5.7.6

macOS 13 (Ventura)
Little Snitch 5.7.6

macOS 12 (Monterey)
Little Snitch 5.7.6

macOS 11 (Big Sur)
Little Snitch 5.7.6

macOS 10.15 (Catalina)
Little Snitch 4.6.1

macOS 10.14 (Mojave)
Little Snitch 4.5.2

macOS 10.13 (High Sierra)
Little Snitch 4.5.2
Little Snitch 3.8.2

macOS 10.12 (Sierra)
Little Snitch 4.5.2
Little Snitch 3.8.2

OS X 10.11 (El Capitan)
Little Snitch 4.5.2
Little Snitch 3.8.2

OS X 10.10 (Yosemite)
Little Snitch 3.8.2

OS X 10.9 (Mavericks)
Little Snitch 3.6.4

OS X 10.8 (Mountain Lion)
Little Snitch 3.3.4
Little Snitch 2.5.4

OS X 10.7 (Lion)
Little Snitch 3.3.4
Little Snitch 2.5.4

OS X 10.6.8 (Snow Leopard)
Little Snitch 3.3.4
Little Snitch 2.5.4

OS X 10.5 (Leopard)
Little Snitch 2.5.4

OS X 10.4 (Tiger)
Little Snitch 2.5.4
Little Snitch 1.2.4

OS X 10.3 (Panther)
Little Snitch 1.2.4

OS X 10.2 (Jaguar)
Little Snitch 1.2.4