Solr vs Elasticsearch vs OpenSearch: Architecture, Licensing, Performance and Which to Choose

The short answer

Choose Elasticsearch for logs, observability and analytics-heavy search where Kibana and Elastic's commercial features matter. Choose OpenSearch for the same jobs under Apache 2.0 or on AWS. Choose Solr for site, product and document search where you want an Apache Software Foundation project, a schema you control, and no vendor between you and the code. All three are built on Apache Lucene, so relevance fundamentals, analysers and index structures are closer than the marketing suggests. The real differences are in cluster management, licensing, tooling and who you can call for support.

Solr vs Elasticsearch vs OpenSearch at a glance

Where they come from

Solr is the older project and lives at the Apache Software Foundation under the Apache License 2.0. It can run in two modes. SolrCloud uses Apache ZooKeeper for central cluster management: ZooKeeper tracks every node and core, and configuration files live in ZooKeeper rather than on each node. User-managed mode, sometimes called standalone, runs nodes without central coordination. Solr bundles an embedded ZooKeeper for getting started, but its own guide strongly encourages an external ensemble in production because the embedded one has no failover.

Elasticsearch was built for distributed operation from the start. Nodes discover each other, elect a master through quorum-based voting and publish cluster state without an external coordinator. Elastic moved Elasticsearch from Apache 2.0 to a dual SSPL and Elastic License in 2021, then added AGPLv3 as a third option for the free portions in 2024; the default distribution is under the Elastic License 2.0. OpenSearch is the Apache 2.0 fork of Elasticsearch 7.10.2, now run by the OpenSearch Software Foundation under the Linux Foundation. Our Elasticsearch vs OpenSearch comparison covers that split in detail.

Schema, queries and analytics

Solr starts from a schema. You define field types and analysers up front, and the schema is the contract between your indexing pipeline and your relevance tuning. Queries go through Solr's query parsers over HTTP, with a JSON request API as an alternative, and faceting arranges results into categories with counts, which suits product catalogues and faceted navigation.

Elasticsearch infers mappings when you index a document it has not seen, which makes it quick to start with, and production teams then pin explicit mappings. Its Query DSL is a JSON query language for searching, filtering and aggregations, and aggregations summarise data as metrics, buckets or pipelines. That aggregation model, together with Kibana or OpenSearch Dashboards, is what makes the Elasticsearch family a natural fit for logs and observability.

Solr vs Elasticsearch: how to choose

• Choose Elasticsearch when you want Kibana, Elastic's commercial features, Elastic Cloud, or a single vendor to support the whole stack, and the Elastic License, SSPL or AGPLv3 terms suit you.
• Choose OpenSearch when you want Elasticsearch-style APIs and dashboards under Apache 2.0, or you run on AWS and want Amazon OpenSearch Service.
• Choose Solr for enterprise, site or e-commerce search with a hand-tuned schema, when you value ASF governance and an Apache 2.0 licence with no commercial edition, or when you already run ZooKeeper and existing Solr applications work well.

Moving between Solr and Elasticsearch is a reindex and a rewrite of queries, analysers and client code, not a configuration change. If your Solr estate is on 8.x or older, patching it while you decide is usually cheaper than migrating under deadline pressure; see the Solr 8 to 9 upgrade guide.

Solr vs Elasticsearch performance

Both run Lucene underneath, so for the same documents, analysers and queries the core indexing and search work is similar. Differences in practice come from configuration: shard and replica counts, caching, refresh and commit intervals, merge policy and JVM sizing. Published comparisons tend to reflect the author's expertise in one engine. Run the same corpus and query log against both, using Elastic's Rally or OpenSearch Benchmark for the Elasticsearch family and your own harness for Solr, on matching hardware.

Solr versions and support today

Solr 10.0.0, released on 3 March 2026, is the current line and needs Java 21 or later. The Solr download page describes 9.11.0, from 4 October 2026, as the last release in the 9.x series. Solr 8 reached end of life on 25 October 2024 and Solr 7 on 11 May 2022. Elastic maintains each Elasticsearch major for at least 30 months from release, and 8.x maintenance ends on 15 January 2027. Our Solr vulnerabilities by version post lists the CVEs open on each Solr line.

Where OSSeva fits

OSSeva supports both families. OSSeva for Apache Solr ships patched builds for Solr 6, 7 and 8 with the index format unchanged, including the bundled Lucene, Jetty and ZooKeeper client libraries, and covers 9.x and 10.x; OSSeva Assure adds a handler exposure audit, a SolrCloud and ZooKeeper review and a reindex-aware upgrade plan. OSSeva for Elasticsearch patches self-managed 7.10.2 and 7.17, and 8.19 once Elastic's 8.x maintenance ends, with OpenSearch as a supported migration target. Both are priced per cluster and sit under one contract with PostgreSQL, Kafka and ZooKeeper. See Solr support providers and Elasticsearch support providers, or book a discovery call for a quote.

Frequently asked questions

Solr vs Elasticsearch: which is better?

Neither in general. Elasticsearch is the stronger choice for logs, metrics and analytics with Kibana; Solr is a strong choice for schema-driven site and product search under Apache governance. Pick on licence, tooling, your team's experience and who will support it, then test relevance on your own data.

Solr vs OpenSearch: what is the difference?

Both are Apache 2.0 and both build on Lucene. OpenSearch inherits Elasticsearch 7.10.2's APIs, built-in cluster coordination and dashboards, and is run by a Linux Foundation project. Solr has its own APIs, uses ZooKeeper in SolrCloud mode and is run by the Apache Software Foundation.

Solr vs Elasticsearch performance: which is faster?

Neither consistently. They share Lucene, so results depend on shard layout, caching, commit settings and query design more than on the engine. Benchmark with your own corpus and query log.

Is Solr still maintained?

Yes. Solr 10.0.0 shipped on 3 March 2026 and 9.11.0 on 4 October 2026 as the last 9.x release. Solr 8 and older receive no upstream security fixes.

Does Elasticsearch use ZooKeeper?

No. Elasticsearch discovers nodes and elects a master itself, using quorum-based voting. SolrCloud is the one that relies on ZooKeeper, and Solr's guide recommends an external ensemble in production.

Is Elasticsearch open source?

Partly. Since 2024 the free portions are available under AGPLv3, an OSI-approved licence, as well as SSPL and the Elastic License 2.0, which is the default. Solr and OpenSearch are Apache 2.0.