Is Wazuh production-grade in 2026?

Yes for SMB and mid-market deployments. Wazuh has matured into the most active open source SIEM community and ships with a usable rule library, an endpoint agent and a managed Wazuh option for those who want the platform without operating the cluster. The honest watch-out is upgrade paths and cluster ops, both of which require capable engineers.

Can open source replace a commercial SIEM in a NIS2-scoped entity?

It can, but the burden of proof shifts. An auditor will ask for documented detection content versioning, evidence of regular update cycles, named owners, log retention chain integrity and operational support arrangements. Commercial SIEM ships with much of that documentation by default; open source requires you to produce it. Either path can satisfy NIS2 when the evidence is in place.

What about Elastic Security? Is it truly open source?

The base Elastic Stack is openly licensed; many security-specific features (advanced detection rules, ML jobs, case management) sit in commercial tiers. Treat Elastic as open source foundation with commercial paid upgrade for production-grade security workflows.

Open source SIEM plus commercial MDR: does that combination work?

Yes, and it is a common pattern for budget-aware regulated entities. The customer owns logs in open source (Wazuh, Elastic) for audit chain integrity, and contracts an MDR to provide detection logic and response on top. Validate that the MDR supports your open source platform natively before signing.

What is the realistic TCO comparison?

For a mid-market environment ingesting 2-3 TB/day with 90-day retention, commercial cloud-native SIEM typically lands at $200k-500k/year in licensing. Open source equivalent has zero licence cost but requires 1.5-2.5 dedicated engineers (loaded cost $200k-350k/year combined) plus infrastructure (~$60-120k/year). The TCO crosses around the same range; the choice is what you prefer to optimize for: capital efficiency vs vendor-grade support. The 2026 shift: managed open source offerings (Wazuh Cloud, Elastic Cloud) are narrowing the operational gap, making open source viable for orgs without dedicated detection engineers at a blended cost of $100-180k/year for mid-market scale.

Independent rankingSilver Support Partner

Best open source SIEM tools 2026: free, defensible, and where to be careful

When open source SIEM makes commercial sense, when it does not, and how to avoid the operational debt that quietly cancels the licence savings.

By Daute Delgado · CEO & Co-founder, PrimedefenceUpdated on 2026-05-21Next review 2026-08-21

Abstract network of open-source modules in cyan with a few violet accent nodes on dark backdrop, open source SIEM

Open source SIEM is the genre most over-recommended and most over-criticized at the same time. Open source advocates pitch it as a free replacement for commercial SIEM; commercial vendors pitch it as an operational disaster waiting to happen. Neither is right. A capable open source SIEM, run by people who know what they are doing, can deliver real detection value at zero licence cost. The same tool, run by a team that underestimated the operational burden, becomes the most expensive log archive on the market: paid in engineering hours. The 2026 truth is that open source SIEM now accounts for an estimated 25-30% of new mid-market SIEM deployments (industry benchmarks), driven by Wazuh's community growth and Elastic's open-foundation model. This guide ranks the leading open source SIEM platforms, names the scenarios where each is the right call, and gives honest cost-of-ownership math.

How this ranking was built

Five open source platforms scored on SOC-CMM Technology (ingestion, storage, search), Process (detection engineering workflow) and a third dimension specific to open source: operational burden over 12 months (cluster ops, upgrades, content maintenance). The total-cost-of-ownership estimate assumes a mid-market environment with 1-3 TB ingested per day and 90-day hot retention. We compared estimated TCO against a commercial cloud-native SIEM in the same scenario, including the salary of dedicated engineering capacity that open source typically requires.

Framework: SOC-CMM 2.4 Technology + Process + operational burden.
Sample: 5 open source SIEM platforms ranked.
TCO model: mid-market scenario, 1-3 TB/day ingestion, 90-day hot retention.
Update commitment: quarterly. Next refresh on 2026-08-21.

Ranking

#1
Wazuh
Best for: Mid-market and SMB SOCs wanting a free SIEM + endpoint platform with active community content.
Deployment: Self-hosted or cloud (managed Wazuh).
Pricing: Free (open source) + optional managed offering.
SOC-CMM scoring
Process
3.0
Technology
4.0
Services
3.0
Strengths
- Largest open source SIEM community in 2026 (20k+ GitHub stars).
- Built-in endpoint agent + log management.
- Strong out-of-the-box rule library (3,500+ pre-built rules).
- Managed Wazuh option lowers operational barrier for mid-market adoption.
Watch-outs
- Cluster operations require capable engineers.
- UI less polished than commercial peers.
- Upgrades occasionally non-trivial.
Visit vendor website
#2
Security Onion
Best for: Network-heavy detection use cases combining IDS, full PCAP and host data.
Deployment: Self-hosted.
Pricing: Free (open source) + commercial support tiers.
SOC-CMM scoring
Process
3.0
Technology
4.0
Services
3.0
Strengths
- Integrated Suricata, Zeek and Strelka.
- Strong network detection out of the box.
- Active community and documentation.
Watch-outs
- Hardware-hungry for full PCAP.
- Best in dedicated detection-engineer hands.
- Cloud deployment less native than peers.
Visit vendor website
#3
Elastic Stack (open license)
Best for: Teams already running Elastic for observability that want shared infrastructure.
Deployment: Self-hosted or Elastic Cloud.
Pricing: Free base + commercial subscription tiers.
SOC-CMM scoring
Process
4.0
Technology
4.0
Services
3.0
Strengths
- Flexible architecture.
- Active Detection Rules repository.
- Strong data ownership story.
Watch-outs
- Cluster scale operations real.
- Many security features sit behind commercial tier.
- Detection content less curated than Wazuh.
Visit vendor website
#4
Graylog Open
Best for: Teams that want clean log management with security features layered on top.
Deployment: Self-hosted.
Pricing: Free (Graylog Open) + commercial Operations and Security tiers.
SOC-CMM scoring
Process
3.0
Technology
3.0
Services
2.0
Strengths
- Clean UX.
- Solid log management foundation.
- Reasonable upgrade path to commercial Security tier.
Watch-outs
- Detection content out of the box modest.
- Security-grade features mostly in commercial tier.
- Smaller community than Elastic/Wazuh.
Visit vendor website
#5
OSSEC (HIDS, foundation for many)
Best for: Host-based intrusion detection foundation, often embedded in other platforms.
Deployment: Self-hosted.
Pricing: Free (open source).
SOC-CMM scoring
Process
2.0
Technology
3.0
Services
2.0
Strengths
- Long-running, well-understood codebase.
- Foundation for Wazuh.
- Minimal footprint.
Watch-outs
- Pure HIDS, not full SIEM.
- Best used as a component.
- UI minimal.
Visit vendor website

Comparison table

Platform	Type	Maintenance load	Best fit	Headcount required (mid-market)
Wazuh	SIEM + HIDS	Medium	SMB / mid-market	1-2 FTE detection engineers
Security Onion	Network-heavy SIEM	High	Network-focused SOC	2-3 FTE engineers
Elastic Stack	Search/SIEM hybrid	High	Existing Elastic shops	2-3 FTE engineers
Graylog Open	Log management + light SIEM	Medium	Logging-first teams	1-2 FTE engineers
OSSEC	HIDS foundation	Low (component)	Foundation layer	Embedded in other ops

When open source SIEM is the right call

Open source SIEM works when three conditions hold simultaneously: you have at least 1-2 dedicated detection engineers, you accept operational burden as a feature (not a bug), and your scale fits within the platform's sweet spot. Outside those conditions, the licence savings get cancelled by engineering hours.

Scenario	Open source fit	Commercial fit
SMB with no security engineers	No	Cloud-native commercial (Microsoft Sentinel, Sumo)
Mid-market with 1-2 detection engineers	Yes (Wazuh)	Optional
Network-heavy enterprise with hunting team	Yes (Security Onion)	Optional
Regulated finance/health, strict audit chain	Risky	Commercial with audit support
Cost is hard constraint and team is mature	Yes	Optional
Lab / training / homelab	Yes	No

When NOT to choose

Open source SIEM is a bad fit when the security team is stretched, when leadership expects vendor-grade support without funding the equivalent engineering capacity internally, and when the regulatory scope (NIS2 essential entities, DORA, ENS) places heavy weight on documented support arrangements and evidence chains. The licence is free; the people are not.

Frequently asked questions

Ready to measure your SOC with the same methodology we used to rank the market?

Primedefence is an official SOC-CMM Silver Support Partner. We apply the 2.4 model to your SOC, prepare per-domain evidence and support the formal certification process through LRQA as the certifying body.

Independent SOC-CMM assessment, no product sales attached.
Evidence coverage mapped to NIS2 (Art. 21), DORA and ENS (Royal Decree 311/2022).
Clear path to official certification with LRQA.

Request a SOC-CMM assessment View full methodology

Verified Silver Support Partner · 2026 SOC-CMM report

Other related rankings

best SIEM tools 2026

Best open source SIEM tools 2026: free, defensible, and where to be careful

How this ranking was built

Ranking

Wazuh

Security Onion

Elastic Stack (open license)

Graylog Open

OSSEC (HIDS, foundation for many)