Best Intrusion Detection and Prevention Software in 2026
Updated
In short: CrowdSec is ranked #1 of 35 as of 4 October 2026, ahead of Wazuh and OSSEC. The best-ranked option with a free plan is Wazuh. The lowest first paid tier on this page is Snort at $2.50/mo.
Intrusion detection and prevention tools help you watch for suspicious activity across networks and systems, and some include inline blocking. Compare network scope, cloud workload support, and deployment model to see which environments each entry covers. Supported platforms, encrypted traffic inspection, and threat intelligence add detail on listed capabilities; free-plan availability and paid-from pricing let you weigh cost as well. Suricata, CrowdSec, and Snort lead the ranking, with SELKS and OPNsense among the entries that follow. Consider which combination of detection, prevention, and platform coverage matches the systems you need to protect.
35 intrusion detection and prevention software ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
10 of the 25 here have a free tier you can use, 0 have open-source code on record, and 0 have full bars: free, open, on most of your devices and documented.
| # | App | Signal | Free tier | Open code | Devices | From | Score |
|---|---|---|---|---|---|---|---|
| 1 | CrowdSecWeb · Windows · Mac · Linux · Self-hosted · API · Extension | Three bars | — | 4 of 6 | Free | 6.6 | |
| 2 | WazuhWeb · Windows · Mac · Linux · Self-hosted · API | Three bars | — | 4 of 6 | $571/mo | 6.6 | |
| 3 | OSSECWindows · Mac · Linux · Self-hosted | Three bars | — | 3 of 6 | $5/mo | 6.5 | |
| 4 | SELKSWeb · Windows · Linux · Self-hosted | Three bars | — | 3 of 6 | Free | 6.5 | |
| 5 | SuricataWindows · Mac · Linux | Three bars | — | 3 of 6 | Free | 6.5 | |
| 6 | Arista NG FirewallWeb | Two bars | — | 1 of 6 | $22.50/mo | 6.4 | |
| 7 | IPFireWeb · Linux · Self-hosted | Two bars | — | 2 of 6 | Free | 6.4 | |
| 8 | OPNsenseWeb · Self-hosted · API | Two bars | — | 1 of 6 | Free | 6.4 | |
| 9 | pfSenseWeb · Linux · Self-hosted | Two bars | — | 2 of 6 | Free | 6.4 | |
| 10 | SnortLinux · Self-hosted | Two bars | — | 1 of 6 | $2.50/mo | 6.3 | |
| 11 | Trellix Data Loss PreventionWeb · Windows · Mac · Self-hosted · API | Two bars | — | — | 3 of 6 | — | 5.6 |
| 12 | Check Point DDoS ProtectorWeb · Linux · Self-hosted | One bar | — | — | 2 of 6 | — | 5.5 |
| 13 | Zscaler Private AccessWeb · Windows · Mac · Linux · Android · iPhone | Two bars | — | — | 6 of 6 | — | 5.4 |
| 14 | Huawei HiSecEngine USG6800GWeb | One bar | — | — | 1 of 6 | — | 5.3 |
| 15 | WatchGuard FireCloudWeb · Windows · Mac · Android · iPhone · Self-hosted · API | Two bars | — | — | 5 of 6 | $8.15/mo | 5.3 |
| 16 | Hillstone Security ManagementNo platforms listed | One bar | — | — | 0 of 6 | — | 5.2 |
| 17 | Forcepoint ZTNAWeb · Windows · Mac · Self-hosted | Two bars | — | — | 3 of 6 | — | 5.1 |
| 18 | FortiGuard DNS Filtering ServiceNo platforms listed | No signal | — | — | 0 of 6 | — | 5.1 |
| 19 | scanlogdLinux | No signal | — | — | 1 of 6 | — | 5.1 |
| 20 | Stormshield Management CenterWeb | No signal | — | — | 1 of 6 | — | 5.1 |
| 21 | WatchGuard FireboxWeb | No signal | — | — | 1 of 6 | — | 5.1 |
| 22 | Zyxel Intrusion Prevention SystemNo platforms listed | No signal | — | — | 0 of 6 | — | 5.1 |
| 23 | AhnLab V3 Internet SecurityWindows | One bar | — | — | 1 of 6 | — | 5.0 |
| 24 | Atomic OSSECWeb · Windows · Mac · Linux | One bar | — | — | 4 of 6 | — | 5.0 |
| 25 | Forcepoint Next Generation FirewallNo platforms listed | No signal | — | — | 0 of 6 | — | 5.0 |
Is your app on this list?
Numbered spots on this list can be sponsored. They are labelled, and the editorial order and scores never change for payment.
Questions about this list
Which intrusion detection and prevention software is ranked first on Freedom251?
CrowdSec is ranked #1 of 35 with a score of 6.6. Wazuh is second and OSSEC third.
How many of these have a free plan?
10 of the 25 on this page publish a free plan on their own pricing pages.
Which is the cheapest paid option?
On this page, Snort has the lowest first paid tier we found: $2.50/mo.
How is this list ranked?
Ranked free-and-open first: a usable free tier and open-source code, then the platforms it runs on and its documentation. Paid placements never change a rank.