OpenSearch vs Elasticsearch: Key Differences Explained

Introduction

OpenSearch and Elasticsearch are powerful, open-source search and analytics engines used for log analytics, full-text search, and real-time data analysis. This article provides a thorough comparison to help teams decide which engine best fits their needs.

Elasticsearch

Elasticsearch is a distributed, RESTful search and analytics engine developed by Elastic NV. Built on top of Apache Lucene, it forms the core of the Elastic Stack (also known as ELK), which includes Kibana, Logstash, and Beats. Elasticsearch has a long track record and a large ecosystem of integrations and commercial features.

OpenSearch

OpenSearch is a community-driven, open-source search and analytics suite derived from Elasticsearch and Kibana. It was initiated by Amazon Web Services (AWS) after Elastic changed the licenses for Elasticsearch and Kibana from Apache 2.0 to SSPL and the Elastic License.

Licensing

Elasticsearch

Starting with version 7.11, Elasticsearch is distributed under the Elastic License or SSPL, neither of which is OSI-approved. This affects how organizations can use, modify, and distribute the software, particularly for managed service providers.

OpenSearch

OpenSearch is released under the Apache 2.0 license, an OSI-approved open-source license. This guarantees that it remains free to use, modify, and distribute for any purpose.

Features Comparison

Core Functionality

Both engines provide:

• Full-text search with advanced query DSL
• Distributed architecture with automatic sharding and replication
• RESTful APIs for indexing and querying
• Aggregation framework for analytics
• Near real-time search capabilities

Plugins & Extensions

Elasticsearch bundles proprietary plugins (X-Pack) for security, alerting, monitoring, and machine learning under a commercial license.

OpenSearch offers open-source alternatives:

• Security plugin -- Role-based access control, encryption, audit logging
• Alerting plugin -- Configurable alerts based on data conditions
• Anomaly Detection -- Machine learning-powered anomaly detection
• SQL plugin -- Query data using SQL syntax
• Index Management -- Automated index lifecycle policies

Compatibility

Elasticsearch: Newer releases may introduce breaking API changes. Open-source builds ceased at version 7.10.

OpenSearch: Forked from Elasticsearch 7.10.2, OpenSearch maintains API compatibility for the time being, though divergence is expected over time as both projects evolve independently.

Community & Support

Elasticsearch is backed by Elastic NV with official commercial support and training. Community contributions flow through a more controlled process.

OpenSearch is community-driven with AWS leadership. The project is fully open to external contributions, and governance is more transparent.

Performance & Scalability

Both engines are built for high-throughput, distributed workloads. Since OpenSearch forked from Elasticsearch 7.10.2, initial benchmarks show similar performance characteristics. Future optimizations may cause the two to diverge.

Security

Elasticsearch provides advanced security features through X-Pack, which requires a commercial license for full functionality.

OpenSearch includes a built-in security plugin under the Apache 2.0 license, offering TLS encryption, authentication, role-based access control, and audit logging at no additional cost.

Visualization Tools

Kibana (Elasticsearch)

Kibana provides dashboards, visualizations, and data exploration tools. From version 7.11 onward, it is distributed under the Elastic License / SSPL.

OpenSearch Dashboards

OpenSearch Dashboards is forked from Kibana 7.10.2 and is fully Apache 2.0 licensed. It provides a similar visualization experience with an open-source guarantee.

Use Cases

• Choose Elasticsearch when the team needs specific commercial features from the Elastic Stack, prefers Elastic's managed cloud offering, or requires advanced ML capabilities built into the platform.
• Choose OpenSearch when open-source licensing is a hard requirement, when running on AWS and wanting native integration, or when avoiding vendor lock-in is a priority.

Pros & Cons Summary

Elasticsearch Pros

• Mature ecosystem with extensive documentation
• Advanced ML and security features via X-Pack
• Strong commercial support from Elastic NV

Elasticsearch Cons

• Restrictive licensing from version 7.11 onward
• Commercial features require paid subscriptions
• Managed service restrictions under SSPL

OpenSearch Pros

• Truly open-source under Apache 2.0
• Built-in security and alerting at no cost
• Active community with AWS backing
• No licensing restrictions for managed services

OpenSearch Cons

• Smaller ecosystem compared to Elastic Stack
• May lag behind Elasticsearch in some advanced features
• Long-term API divergence from Elasticsearch

Final Thoughts

Both OpenSearch and Elasticsearch excel at search and analytics workloads. OpenSearch guarantees open-source freedom and includes security features at no cost, while Elasticsearch provides a deeper set of commercial features under more restrictive licensing. We recommend choosing based on the project's specific feature requirements, licensing constraints, and support needs.