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OpenSearch

Open-source search engine with vector and hybrid retrieval

open sourceverified Aug 24, 2026

OpenSearch is an Apache-2.0 distributed search engine with native vector-search support for teams that want BM25, filters, aggregations, and k-NN retrieval in the same search stack. It is distinct from Elasticsearch in the aicoolies catalog: OpenSearch is the AWS-backed open fork with its own docs, plugin path, and serverless deployment options.

Read our OpenSearch review

A detailed review by the aicoolies team — click to read

OpenSearch fits the vector-database category as a hybrid search-engine path rather than a dedicated AI-native vector store. The official documentation describes vector search techniques for nearest-neighbor retrieval, while Amazon OpenSearch Serverless documents vector-search collections for generative-AI and RAG workloads. That gives developers a way to add semantic retrieval to an operational search cluster instead of standing up Pinecone, Milvus, Qdrant, or Weaviate as a separate system.

The strongest positioning is hybrid retrieval. OpenSearch keeps mature lexical search, filters, aggregations, dashboards, and operational-search habits while adding k-NN/vector search for embeddings. This matters for product search, internal knowledge search, observability-like document search, and RAG pipelines where keyword precision and metadata filtering are still as important as approximate-nearest-neighbor recall.

OpenSearch is Apache-2.0 open source, and the live GitHub repository check on July 9, 2026 showed the opensearch-project/OpenSearch repository as active, non-archived, Apache-2.0 licensed, and recently pushed. The page should avoid treating the project as just another Elasticsearch alias: existing aicoolies slug elasticsearch covers Elastic’s product family, while this record covers the OpenSearch project and its managed-service ecosystem.

Pricing depends on deployment. Self-hosting the open-source project is free apart from infrastructure and operations cost. Managed OpenSearch options, including Amazon OpenSearch Serverless, use cloud-provider pricing models; those numbers can change, so this tool page uses durable wording instead of hard-coding a monthly minimum. Teams should compare index size, vector dimensions, ingestion rate, query rate, and operational staffing before choosing this path over a managed vector-only database.

OpenSearch is best for teams that already understand search relevance and want vector retrieval to live near full-text ranking and structured filters. It is weaker for teams that want a turnkey vector database with minimal operations, model-native SDK defaults, and simplified RAG templates. In those cases Pinecone, Turbopuffer, Qdrant Cloud, or Weaviate Cloud may be easier to adopt.

The practical evaluation question is not whether OpenSearch can store embeddings; it can. The question is whether your retrieval workload benefits from the full search-engine surface area: analyzers, synonym handling, fielded search, aggregations, security controls, scaling knobs, and Lucene-style operational maturity. If those features matter, OpenSearch deserves a separate shortlist slot from both Elasticsearch and dedicated vector stores.

Pricing

Open-source distributed search and analytics suite licensed under Apache-2.0 (OpenSearch Software Foundation / Linux Foundation). The core software and all enterprise-grade features (security, alerting, k-NN vector search, OpenSearch Dashboards) are 100% free with zero software licensing costs for unlimited self-hosted nodes. Managed cloud deployments are available via Amazon OpenSearch Service (hourly instance/compute and EBS storage pricing with Reserved Instance discounts) and Amazon OpenSearch Serverless (usage-based billing per OpenSearch Compute Unit / OCU).

full pricing breakdown →

Platforms

Self-hosted search cluster, Kubernetes/Docker deployments, and managed OpenSearch services for teams that want full-text, filtering, analytics, and vector search in one engine.

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FAQ

What is OpenSearch?

OpenSearch is an Apache-2.0 distributed search engine with native vector-search support for teams that want BM25, filters, aggregations, and k-NN retrieval in the same search stack. It is distinct from Elasticsearch in the aicoolies catalog: OpenSearch is the AWS-backed open fork with its own docs, plugin path, and serverless deployment options.

Is OpenSearch free?

Yes — OpenSearch is open source and free to use. Open-source distributed search and analytics suite licensed under Apache-2.0 (OpenSearch Software Foundation / Linux Foundation). The core software and all enterprise-grade features (security, alerting, k-NN vector search, OpenSearch Dashboards) are 100% free with zero software licensing costs for unlimited self-hosted nodes. Managed cloud deployments are available via Amazon OpenSearch Service (hourly instance/compute and EBS storage pricing with Reserved Instance discounts) and Amazon OpenSearch Serverless (usage-based billing per OpenSearch Compute Unit / OCU).

Is OpenSearch open source?

Yes — OpenSearch is open source.

Is OpenSearch still maintained?

Yes — OpenSearch is active. Its listing was last verified on August 24, 2026.

How does OpenSearch score in our review?

Our hands-on review scores OpenSearch 82/100 overall, based on speed, privacy, and developer-experience testing.