Open Source SIEM Tools -- Splunk Alternatives

Best Open Source SIEM Alternatives to Splunk in 2026

Open source SIEM tools provide cost-effective security monitoring with full transparency into detection logic and data handling. By eliminating per-GB ingest costs and allowing self-hosted deployments, these tools give security teams complete control over their SIEM infrastructure. They are ideal for organizations that want to avoid vendor lock-in, customize detection rules, and reduce the escalating costs of enterprise SIEM platforms like Splunk.

Our Recommendations

1

Elastic Security

Free (basic) / From $95/month (Cloud) / Enterprise custom

The most capable open-source SIEM alternative to Splunk, offering unified SIEM, EDR, and cloud security on the ELK Stack. Best for teams that want enterprise-grade detection without per-GB ingest costs and can manage Elasticsearch clusters.

2

Graylog

Free (Open) / From $1,250/month (Operations) / Security custom

A more approachable open-source option with an intuitive interface and powerful pipeline processing. Best for teams that need centralized log management with SIEM capabilities at a fraction of Splunk's cost and complexity.

Detailed Tool Profiles

Elastic Security

Open Source SIEM
4.5

Open-source SIEM and security analytics built on the ELK Stack

Pricing

Free (basic) / From $95/month (Cloud) / Enterprise custom

Best For

Teams wanting open-source flexibility with enterprise SIEM capabilities and no per-GB ingest pricing

Key Features
SIEM with detection engine and rulesEndpoint detection and response (EDR)Cloud security posture managementMITRE ATT&CK-aligned detection rules+4 more
Pros
  • +Open-source core with no ingest-based pricing
  • +Scales massively with Elasticsearch
  • +Unified SIEM, EDR, and cloud security
Cons
  • –Complex cluster management at scale
  • –Advanced features require paid subscription
  • –Steeper operational overhead than SaaS alternatives
Open SourceCloudSelf-Hosted
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Graylog

Open Source SIEM
4.2

Open-source log management and SIEM platform with intuitive analytics

Pricing

Free (Open) / From $1,250/month (Operations) / Security custom

Best For

Teams needing cost-effective log management with SIEM capabilities and an intuitive user experience

Key Features
Centralized log management and collectionSecurity analytics and threat detectionPipeline processing for data enrichmentAnomaly detection with machine learning+4 more
Pros
  • +Open-source core with generous free tier
  • +Intuitive UI with lower learning curve than Splunk
  • +Efficient resource utilization and storage
Cons
  • –Smaller community and ecosystem than Splunk or Elastic
  • –Security features less mature than dedicated SIEMs
  • –Limited out-of-the-box security content
Open SourceCloudSelf-Hosted
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Splunk Alternatives Feature Comparison

Compare all 2 Splunk alternatives side-by-side across pricing, deployment, and key capabilities.

Feature
Elastic Security
4.5/5
Graylog
4.2/5
Pricing ModelResource-based (nodes/capacity)Per-node licensing (Operations and Security tiers)
Open Source++
Cloud-Hosted++
Self-Hosted++
Best ForTeams wanting open-source flexibility with enterprise SIEM capabilities and no per-GB ingest pricingTeams needing cost-effective log management with SIEM capabilities and an intuitive user experience
Key Features
  • •SIEM with detection engine and rules
  • •Endpoint detection and response (EDR)
  • •Cloud security posture management
  • •MITRE ATT&CK-aligned detection rules
  • •Centralized log management and collection
  • •Security analytics and threat detection
  • •Pipeline processing for data enrichment
  • •Anomaly detection with machine learning
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Open Source SIEM Tools FAQ

Can open source SIEM tools really replace Splunk?

For many organizations, yes. Elastic Security in particular has matured significantly and provides SIEM, endpoint detection, and cloud security in a single platform. While Splunk still leads in query flexibility (SPL), app ecosystem breadth, and managed SOAR, open source SIEMs can handle core security monitoring, threat detection, and compliance at a dramatically lower cost. The tradeoff is that you need operational expertise to deploy and maintain the infrastructure.

What are the cost savings of switching from Splunk to an open source SIEM?

Organizations typically report 50-80% cost reductions when moving from Splunk to open source SIEMs like Elastic Security or Graylog. The savings come primarily from eliminating per-GB ingest licensing, which is Splunk's largest cost driver at scale. However, factor in the operational cost of managing your own infrastructure, hiring or training Elasticsearch administrators, and the time investment in building custom detection content.

How does Elastic Security compare to Graylog for SIEM use cases?

Elastic Security is the more feature-complete SIEM, offering detection rules, EDR, cloud security posture management, and machine learning anomaly detection. Graylog excels at log management with an intuitive interface and powerful pipeline processing but has less mature security-specific features. Choose Elastic Security for a full SIEM replacement; choose Graylog for cost-effective log management with basic SIEM capabilities.

What skills does my team need to run an open source SIEM?

Running an open source SIEM requires skills in Linux administration, the underlying data store (Elasticsearch for Elastic Security, MongoDB and OpenSearch for Graylog), cluster management, capacity planning, and security content development. Your team should be comfortable writing detection rules, managing data pipelines, and troubleshooting distributed systems. Many organizations start with managed cloud offerings (Elastic Cloud, Graylog Cloud) to reduce the operational burden.

Related Guides

Comparison

Splunk vs Elastic Security

Open-source SIEM and security analytics built on the ELK Stack

Comparison

Splunk vs Graylog

Open-source log management and SIEM platform with intuitive analytics

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