OpenSearch
Open-source search and analytics engine forked from Elasticsearch
OpenSearch is an open-source search and analytics engine, originally forked from Elasticsearch after a licensing change, used for full-text search, log analytics, and observability workloads. It provides a distributed, JSON-document-based…
Definition
OpenSearch is an open-source search and analytics engine, originally forked from Elasticsearch after a licensing change, used for full-text search, log analytics, and observability workloads. It provides a distributed, JSON-document-based search engine with a REST API, along with visualization tooling through OpenSearch Dashboards. OpenSearch addresses the need some organizations had for a fully open-source search engine after Elastic moved Elasticsearch and Kibana to a more restrictive, source-available license, preserving a freely licensed continuation of the codebase those users depended on.
Overview
OpenSearch originated when Amazon Web Services forked the last Apache 2.0-licensed version of Elasticsearch and Kibana after Elastic changed those projects' licenses to a source-available model that restricted certain managed-service use cases. AWS, along with other contributors, continued developing the forked codebase under the OpenSearch name, aiming to preserve a fully open-source alternative with a compatible feature set and API surface for existing Elasticsearch users. Architecturally, OpenSearch retains much of Elasticsearch's original design: data is indexed as JSON documents distributed across shards for horizontal scalability, queries use a JSON-based query DSL, and full-text search relies on inverted indexes built on Apache Lucene, the same underlying search library Elasticsearch uses. This shared foundation means many concepts, query patterns, and client libraries familiar to Elasticsearch users carry over to OpenSearch with minimal changes, particularly for versions close to the fork point. OpenSearch Dashboards, the forked equivalent of Kibana, provides visualization and exploration tools for data indexed in OpenSearch, commonly used for log analytics, security monitoring, and operational dashboards. This positions OpenSearch alongside Elasticsearch itself and general-purpose search engines like Apache Solr, though its closest relative in architecture and query language remains Elasticsearch, from which it diverged. In practice, organizations run OpenSearch for full-text search on websites and catalogs, centralized log aggregation, and security monitoring dashboards, often via Amazon OpenSearch Service, a managed offering that handles cluster provisioning and operations, similar to how Elastic offers its own managed Elasticsearch service. Since the fork, OpenSearch and Elasticsearch have continued to diverge in features and internals as each project develops independently. Compatibility between the two is strongest for older API versions and gradually decreases for features introduced after the split, so organizations choosing between them weigh licensing preferences against feature parity and community size considerations. OpenSearch competes with Elasticsearch itself, as well as with other search and analytics platforms; its main appeal is a fully open-source license combined with strong compatibility with the pre-fork Elasticsearch ecosystem and deep integration with AWS services. Teams already committed to newer, post-fork Elasticsearch features may find migrating to OpenSearch requires more rework than teams whose usage stayed close to the shared, pre-fork feature set, and the choice often ends up being decided as much by an organization's licensing preferences and existing cloud vendor relationship as by any specific feature-by-feature comparison between the two projects and their respective roadmaps going forward, since both continue to add features the other does not necessarily match.
Key Features
- Forked from the last Apache 2.0-licensed Elasticsearch and Kibana releases
- Distributed, JSON-document search built on Apache Lucene
- JSON-based query DSL for full-text and structured search
- OpenSearch Dashboards for visualization and log analytics
- Amazon OpenSearch Service as a managed cloud offering
- Fully open-source licensing under Apache 2.0
- Security and alerting plugins for observability use cases
- Broad compatibility with pre-fork Elasticsearch clients and tooling