Best Free Firewalls 2026: 8 Options Compared

Free firewalls come in two kinds and the right one depends on what you are protecting. Host firewalls run on a single computer and control which programs may use the network. Windows Firewall ships with Windows and is enabled by default, and UFW is a command-line front end that ships with Ubuntu. If you want per-application prompts, simplewall configures the Windows Filtering Platform for advanced users, Portmaster adds a guided network monitor on Windows and Linux with a free plan, and OpenSnitch is an interactive outbound firewall for Linux inspired by Little Snitch. Network firewalls protect a whole site and run on their own machine: OPNsense and pfSense Community Edition are full open-source firewall distributions, and OpenWrt replaces router firmware with a built-in nftables firewall on supported routers. The trade-off is control against noise. Application firewalls that ask about every connection teach you a lot in the first week and then become tedious, and a wrong block can break an update or a game. For most home users the built-in firewall plus a decent router is enough, and a dedicated firewall box makes sense when you run a lab, a small office or many devices you cannot patch.

Windows Firewall

Included with Windows and enabled by default, blocking unsolicited inbound traffic with rules by app, IP, port and protocol. No extra software is required, but outbound control is limited by default.

Price: Free (Included with Windows and enabled by default; no additional hardware or software required) (Windows Firewall pricing, checked 2026-10-24).

Platforms and license: Windows. Proprietary (part of Windows).

Best for: Everyone on Windows as the baseline.

UFW (Uncomplicated Firewall)

Ships with Ubuntu since 8.04 LTS as a front end to netfilter. The wiki page names no software license, so confirm one for your distribution; it is command-line only.

Price: Free (Included with Ubuntu at no extra cost; command-line front end for iptables) (UFW (Uncomplicated Firewall) pricing, checked 2026-10-24).

Platforms and license: Ubuntu (included by default since 8.04 LTS), Other Linux distributions. Not stated.

Best for: Simple host rules on Ubuntu.

simplewall

GPL-3.0 Windows tool that configures the Windows Filtering Platform. Free and open source, but described as for advanced users.

Price: Free (free, open source) (simplewall pricing, checked 2026-10-22).

Platforms and license: Windows. GPL-3.0 (open source).

Project activity: 9.2k GitHub stars · latest release v.3.8.7 (Aug 8, 2025) · last commit Oct 27, 2026

Best for: Per-application control on Windows.

Worth knowing: Configures Windows Filtering Platform; described as for advanced users.

Portmaster

GPL-3.0 for Windows and Linux with a free forever plan; Plus is 40 EUR a year and adds network history and bandwidth visibility. Includes a network monitor.

Price: Free (Free forever plan); paid from EUR 40 per year (Plus) (Portmaster pricing, checked 2026-10-22).

Platforms and license: Windows, Linux. GPL-3.0 (open source).

Project activity: 14k GitHub stars · latest release v2.2.3 (Aug 14, 2026) · last commit Oct 27, 2026

Best for: Seeing what connects out, with a guided interface.

Worth knowing: Pro is 8 EUR per month or 80 EUR per year; paid tiers add network history and bandwidth visibility.

OpenSnitch

GPL-3.0 interactive outbound firewall for GNU/Linux, inspired by Little Snitch. Linux only, and it prompts for each new connection.

Price: Free (free, open source) (OpenSnitch pricing, checked 2026-10-22).

Platforms and license: Linux. GPL-3.0 (open source).

Project activity: 14.2k GitHub stars · latest release v1.8.0 (Dec 15, 2025) · last commit Jul 26, 2026

Best for: Outbound control on a Linux desktop.

Worth knowing: Interactive outbound firewall inspired by Little Snitch; GNU/Linux only.

OPNsense

BSD-2-Clause FreeBSD-based firewall that replaces an appliance. It protects the network, not endpoints, and you need spare hardware.

Price: Free (OPNsense pricing, checked 2026-10-22).

Platforms and license: Self-hosted firewall (FreeBSD-based). BSD-2-Clause (open source).

Project activity: 4.8k GitHub stars · last commit Oct 27, 2026

Best for: A home lab or small office gateway.

Worth knowing: Replaces a firewall appliance, not endpoint protection.

pfSense Community Edition

Apache-2.0 firewall distribution downloaded through Netgate's store. Commercial support is sold without published prices; runs on your own hardware.

Price: Free (pfSense Community Edition pricing, checked 2026-10-22).

Platforms and license: Self-hosted firewall. Apache-2.0 (open source).

Project activity: 5.8k GitHub stars · last commit Mar 31, 2026

Best for: Teams used to the pfSense ecosystem.

Worth knowing: Download goes through Netgate's store; commercial support is sold separately without published prices.

OpenWrt

GPL-2.0 router firmware with a firewall4 (nftables) firewall on supported routers. It replaces firmware on a router rather than running on a PC.

Price: Free (provided without any monetary cost; you need a supported router) (OpenWrt pricing, checked 2026-10-23).

Platforms and license: Router firmware (supported devices). GPL-2.0 (open source).

Project activity: 29k GitHub stars · latest release v25.12.6 (Oct 18, 2026) · last commit Oct 27, 2026

Best for: Getting a real firewall on a compatible router.

Worth knowing: Firewall is firewall4 (fw4), which builds nftables rules from its config. It replaces router firmware rather than running as an app on a PC.

Which one to pick

• You use Windows and want to keep it simple: Windows Firewall
• You want to approve each program's connections on Windows: simplewall
• You want that on a Linux desktop: OpenSnitch
• You are building a home lab gateway: OPNsense
• Your router is supported by OpenWrt: OpenWrt