10 Best Open Source Databases of 2026

1. 1

   PostgreSQL

   Open source object-relational database with nearly 40 years of development on its core platform.

   9.9overall

   Open source object-relational database with nearly 40 years of development on its core platform.

   Best fordevelopers who want one general-purpose database with no vendor lock-in

   Adoption data

   57.9%57.9% of the 12,061 respondents to the database question in the 2026 Stack Overflow Developer Survey had done extensive work in PostgreSQL over the past year, the top share of any database.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “PostgreSQL 6,984 57.9%”

   PostgreSQL is the safest open source choice for a new application database, both on adoption and on license terms. In the 2026 Stack Overflow survey, 57.9% of database respondents had worked extensively with it, ahead of SQLite at 42.1% and MySQL at 35.1%. Its license is a few paragraphs long and grants permission to use, copy, modify and distribute the software for any purpose without a fee, which means no edition gating and no relicensing risk from a single owner. The project traces back to the 1986 POSTGRES project at Berkeley, has been ACID-compliant since 2001 and, as of version 18, conforms to at least 170 of the 177 mandatory SQL:2023 Core features. Extensions such as PostGIS let one server handle relational and geospatial data. The cost is operational: you install, tune, back up and upgrade it yourself, or pay a host to do so. Because nearly every cloud and hosting company runs PostgreSQL, moving between them is straightforward.

   Strengths

   • +Highest developer usage in the 2026 Stack Overflow survey at 57.9%
   • +Governed by the PostgreSQL Global Development Group, not a single company
   • +Permissive license lets you embed or fork it freely

   Limitations

   • −You operate the server, backups and upgrades yourself
   • −No vendor support contract unless you hire a third party
   • −Heavier to set up than an embedded engine such as SQLite

   SummaryPostgreSQL is the best open source database for most developers because it pairs a 57.9% usage share in the 2026 Stack Overflow survey with a license that lets you use and modify it for any purpose without fee. Start here unless your workload is embedded, analytical or graph-shaped.

2. 2

   SQLite

   In-process, serverless SQL database engine whose source code is in the public domain.

   9.2overall

   In-process, serverless SQL database engine whose source code is in the public domain.

   Best forapp developers who need an embedded database with no server

   Adoption data

   42.1%42.1% of database respondents in the 2026 Stack Overflow Developer Survey had done extensive work in SQLite over the past year.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “SQLite 5,083 42.1%”

   SQLite is the most lock-in proof database on this list because its code is in the public domain: there is no license text to follow and no owner who can change terms. The project describes itself as an in-process library that implements a self-contained, serverless, zero-configuration, transactional SQL engine, and says it is the most widely deployed database in the world. A whole database lives in one file, which can grow to 281 terabytes, and rows can be up to 1 gigabyte. That makes it the default for mobile apps, desktop software, command-line tools and test suites, and 42.1% of database respondents in the 2026 Stack Overflow survey had used it extensively. The tradeoff is concurrency and networking. SQLite runs inside your process, so it is not meant to serve many writers across a network, and it has no user accounts of its own. For a shared multi-user server, PostgreSQL, MySQL or MariaDB fit better.

   Strengths

   • +Public domain, so there is no license to comply with
   • +Nothing to install or run as a separate server
   • +Second highest usage in the 2026 Stack Overflow survey at 42.1%

   Limitations

   • −Not built for many concurrent writers over a network
   • −No user accounts or network access layer of its own
   • −You add replication and backups through your app or other tools

   SummarySQLite is the best choice for developers who need a database inside their app because it is public domain and stores everything in one file with no server. Choose a server engine instead when many clients write at once.

3. 3

   MariaDB Server

   Community fork of MySQL run by the MariaDB Foundation and pledged to stay GPLv2.

   8.9overall

   Community fork of MySQL run by the MariaDB Foundation and pledged to stay GPLv2.

   Best forMySQL users who want foundation governance

   Adoption data

   20.3%20.3% of database respondents in the 2026 Stack Overflow Developer Survey had done extensive work in MariaDB over the past year.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “MariaDB 2,446 20.3%”

   MariaDB Server is the answer for teams that like MySQL but want stronger assurance about who controls it. The MariaDB Foundation states that the server will remain free and open source software under GPLv2, independent of any commercial entities, and lists Wikipedia, WordPress.com and Google among notable users. It was originally designed as an enhanced, drop-in replacement for MySQL, so most applications, drivers and admin habits carry over, and it adds a range of storage engines and plugins. In the 2026 Stack Overflow survey, 20.3% of database respondents had used it extensively, which puts it well ahead of most specialist engines. The caveat is that MariaDB and MySQL have diverged over the years, so test newer features and replication setups before you switch. As with MySQL, the GPL matters mainly if you ship modified code to others.

   Strengths

   • +Written pledge to remain GPLv2 independent of any commercial entity
   • +Usually an easy move from MySQL
   • +20.3% usage in the 2026 Stack Overflow survey

   Limitations

   • −Has drifted from MySQL over time, so check compatibility for newer features
   • −GPL obligations apply if you distribute modified code
   • −Smaller community than MySQL or PostgreSQL

   SummaryMariaDB Server is the best choice for MySQL users who want foundation governance because the MariaDB Foundation commits to keeping it GPLv2 independent of any company. It ranks just behind MySQL on adoption.

4. 4

   MySQL

   Oracle's open source relational database server, the long-time default for web stacks.

   8.9overall

   Oracle's open source relational database server, the long-time default for web stacks.

   Best forweb developers on LAMP stacks and WordPress hosting

   Adoption data

   35.1%35.1% of database respondents in the 2026 Stack Overflow Developer Survey had done extensive work in MySQL over the past year.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “MySQL 4,235 35.1%”

   MySQL is still the database behind a large share of the web, and 35.1% of database respondents in the 2026 Stack Overflow survey had used it extensively, third behind PostgreSQL and SQLite. Its repository describes it as the world's most popular open source database, and the same source tree includes MySQL Cluster, a real-time transactional database. For a web app on PHP, WordPress or a typical shared host, MySQL is the path of least resistance because hosts, frameworks and admins already support it. The lock-in question is about governance rather than code. MySQL is developed by the MySQL team at Oracle, which also sells commercial editions, so the roadmap follows one company's plans. If that concerns you, MariaDB began as a drop-in replacement for MySQL and is run by a foundation, and moving between the two is usually simple. Like any server engine, MySQL leaves backups, upgrades and tuning to you.

   Strengths

   • +Third highest usage in the 2026 Stack Overflow survey at 35.1%
   • +Huge pool of hosting options, tutorials and administrators
   • +Free community server covers most web workloads

   Limitations

   • −Owned and steered by one company, Oracle
   • −GPL terms apply if you distribute modified code
   • −Some features are reserved for Oracle's commercial editions

   SummaryMySQL is the best choice for web developers on LAMP stacks because 35.1% of developers in the 2026 Stack Overflow survey use it and almost every host supports it. Pick MariaDB if you want the same model under foundation governance.

5. 5

   DuckDB

   In-process analytical SQL database under the MIT license, held by the non-profit DuckDB Foundation.

   8.3overall

   In-process analytical SQL database under the MIT license, held by the non-profit DuckDB Foundation.

   Best fordata analysts and engineers querying local files

   Adoption data

   5.7%5.7% of database respondents in the 2026 Stack Overflow Developer Survey had done extensive work in DuckDB over the past year.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “DuckDB 690 5.7%”

   DuckDB is the open source pick for analytics without infrastructure. It runs inside your Python, R, Node.js or other process, has no external dependencies, and is built for OLAP queries such as aggregations over whole tables and joins between large tables. It provides ACID guarantees through its own bulk-optimized MVCC, can store data in a single file or in lakehouse formats, and can even run in a browser through DuckDB-Wasm. On lock-in, the terms are unusually clear: the FAQ says all components are in the free MIT-licensed version and there is no enterprise version, and the DuckDB Foundation's statutes keep it under MIT in perpetuity. Adoption is smaller than the general-purpose engines, at 5.7% of database respondents in the 2026 Stack Overflow survey. It is not meant to be the main transactional database behind a busy web app; pair it with PostgreSQL or SQLite for that.

   Strengths

   • +Every feature is in the MIT-licensed free version
   • +Foundation statutes keep it open source under MIT in perpetuity
   • +Queries Pandas data in Python without copying it

   Limitations

   • −Built for analytics, not for many small transactional writes
   • −Not a shared multi-user server by default
   • −5.7% survey usage means a smaller pool of answers than PostgreSQL

   SummaryDuckDB is the best choice for analysts querying local data because it runs in-process with no dependencies and has no enterprise edition held back. Use it beside, not instead of, a transactional database.

6. 6

   ClickHouse

   Open source, column-oriented SQL database for real-time analytics at petabyte scale.

   8.1overall

   Open source, column-oriented SQL database for real-time analytics at petabyte scale.

   Best forteams running real-time analytics and observability on large data

   Adoption data

   3.6%3.6% of database respondents in the 2026 Stack Overflow Developer Survey had done extensive work in ClickHouse over the past year.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “Clickhouse 429 3.6%”

   ClickHouse is the open source engine to reach for when analytical data outgrows a single-file tool like DuckDB. The project describes itself as an open-source, column-oriented SQL database built for speed and scale, running anywhere from a laptop to hundreds of servers at petabyte scale, and its single binary covers application analytics, warehousing and observability. The main repository is Apache 2.0 licensed and has 50.9k GitHub stars, and installation on macOS, Linux and FreeBSD is one shell command, with Windows and Docker options documented. Adoption among general developers is narrower, at 3.6% of database respondents in the 2026 Stack Overflow survey, because it serves a specific job. It is not designed for frequent single-row updates, and running a large cluster well takes experience. ClickHouse Inc. sells ClickHouse Cloud, but the open source server is a full product you can host yourself.

   Strengths

   • +Apache 2.0 license on the main repository
   • +50.9k GitHub stars on ClickHouse/ClickHouse
   • +Scales from one machine to large clusters

   Limitations

   • −Not a fit for row-by-row transactional updates
   • −Cluster operation takes real expertise
   • −Led by one company, ClickHouse Inc., which also sells a cloud service

   SummaryClickHouse is the best choice for teams running real-time analytics on large data because it is an Apache 2.0 column store that scales from a laptop to petabytes. Keep a separate transactional database for app writes.

7. 7

   Valkey

   BSD-licensed key-value datastore backed by the Linux Foundation.

   8.0overall

   BSD-licensed key-value datastore backed by the Linux Foundation.

   Best forteams that need caching and queues under a permissive license

   Adoption data

   5.0%5.0% of database respondents in the 2026 Stack Overflow Developer Survey had done extensive work in Valkey over the past year.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “Valkey 603 5.0%”

   Valkey is the open source key-value store for teams that want Redis-style caching without license uncertainty. The project calls itself an open source (BSD) datastore for caching, message queues and primary database use, and says Linux Foundation backing ensures it will remain open source forever. Its site notes that it includes 3-Clause BSD-licensed Redis code, which is why existing Redis clients and commands generally carry over. The latest release line, Valkey 9.1, lists 2.1 million requests per second on a single server thanks to a redesigned I/O threading model, up to 20% less memory for small strings, per-database ACLs and Lua scripting moved into an optional module. Adoption is still building: 5.0% of database respondents in the 2026 Stack Overflow survey had used it extensively, compared with 28.3% for Redis. Like any in-memory store, it is best beside a relational database rather than in place of one.

   Strengths

   • +BSD license with Linux Foundation backing
   • +Includes BSD-licensed Redis code, so Redis clients and habits carry over
   • +Active release cadence, with 9.1.3 released October 26, 2026

   Limitations

   • −Data must fit in memory for its main use cases
   • −5.0% survey usage, behind Redis at 28.3%
   • −Not a replacement for a relational database's queries and joins

   SummaryValkey is the best choice for teams that need caching and queues under a permissive license because it is BSD licensed and backed by the Linux Foundation. Pair it with PostgreSQL or MySQL for durable relational data.

8. 8

   Apache Cassandra

   Apache Software Foundation's masterless, distributed NoSQL database.

   7.8overall

   Apache Software Foundation's masterless, distributed NoSQL database.

   Best forteams with high write volume across many nodes or data centers

   Adoption data

   2.5%2.5% of database respondents in the 2026 Stack Overflow Developer Survey had done extensive work in Cassandra over the past year.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “Cassandra 300 2.5%”

   Apache Cassandra is the open source choice when a single database server is no longer enough and writes must keep flowing through hardware failures. The project's basics guide describes a masterless design where any node can do what any other node does, nodes that coordinate through gossip, and clusters that can span multiple data centers. Capacity grows by adding nodes with no downtime, and the docs say doubling nodes doubles capacity or throughput. Governance is a strong point for lock-in: Cassandra is an Apache Software Foundation project under the Apache License 2.0, so no single company owns it. The cost is complexity. The docs themselves note there is little point running Cassandra as one node, data modeling starts from your queries rather than from normalized tables, and only 2.5% of database respondents in the 2026 Stack Overflow survey had used it extensively. For most apps, PostgreSQL is simpler until you hit real scale.

   Strengths

   • +Governed by the Apache Software Foundation under Apache 2.0
   • +Scales horizontally on commodity hardware
   • +No single node whose failure takes the cluster down

   Limitations

   • −Its own docs say there is little point running it as a single node
   • −Data modeling is query-first and differs from relational design
   • −2.5% survey usage means fewer developers know it

   SummaryApache Cassandra is the best choice for write-heavy systems across many nodes because its masterless design lets you add nodes with no downtime. It is overkill for apps that fit on one server.

9. 9

   Neo4j Community Edition

   GPL v3 edition of the Neo4j graph database with the Cypher query language.

   7.2overall

   GPL v3 edition of the Neo4j graph database with the Cypher query language.

   Best fordevelopers modeling connected data as nodes and relationships

   Adoption data

   2.8%2.8% of database respondents in the 2026 Stack Overflow Developer Survey had done extensive work in Neo4j over the past year.

   Stack Overflow, Databases, Technology data 2026, Stack Overflow Developer Survey (2026): “Neo4J 332 2.8%”

   Neo4j Community Edition is the open source route into graph databases, and Neo4j was the most used graph engine in the 2026 Stack Overflow survey at 2.8% of database respondents. Its repository describes a high-performance graph store with ACID transactions, where programmers work with nodes and relationships rather than static tables, queried through Cypher. Neo4j's licensing page lists Community Edition under GPL v3, and the code is on GitHub with 17.4k stars. That makes it a good fit for recommendation engines, fraud graphs, knowledge graphs and GraphRAG experiments that are awkward in SQL joins. The lock-in picture is mixed. The free edition is real open source, but Neo4j Inc. sells Enterprise and the managed AuraDB, with AuraDB Professional starting at $0.09 per GB per hour. The GPL v3 also has stronger copyleft terms than the Apache or MIT licenses elsewhere on this list.

   Strengths

   • +Most used graph database in the 2026 Stack Overflow survey at 2.8%
   • +Free GPL v3 edition you can self-host
   • +17.4k GitHub stars and large learning resources such as GraphAcademy

   Limitations

   • −GPL v3 copyleft applies if you distribute modified code
   • −Paid support and managed hosting come through Neo4j's commercial Enterprise and AuraDB offerings
   • −Led by a single company, Neo4j Inc.

   SummaryNeo4j Community Edition is the best choice for developers modeling connected data because it is the most used graph database in the 2026 Stack Overflow survey and is free under GPL v3. Compare it with Neo4j's paid editions before planning large production deployments.

10. 10

    YugabyteDB

    PostgreSQL-compatible distributed SQL database under the Apache 2.0 license.

    7.1overall

    PostgreSQL-compatible distributed SQL database under the Apache 2.0 license.

    Best forteams that need PostgreSQL-style SQL across regions

    YugabyteDB fills a gap the other engines leave: PostgreSQL-style SQL that spreads across many nodes and regions while staying open source. Its repository says the database is fully open source under the Apache 2.0 license, and that the open source version includes distributed backups, encryption at rest, TLS in flight, change data capture and read replicas. The YSQL API reuses the PostgreSQL query layer, so most data types, queries, stored procedures, triggers and extensions work, and a second YCQL API draws on the Cassandra query language. Writes are replicated with Raft consensus and transactions follow the Google Spanner design, with snapshot, serializable and read committed isolation. We score adoption conservatively because the 2026 Stack Overflow survey does not list it separately. Note the licensing split: the YugabyteDB Anywhere management platform is under a Polyform Free Trial license, so plan to operate the open source core with your own tooling.

    Strengths

    • +Apache 2.0 core with enterprise features such as encryption at rest included
    • +PostgreSQL compatibility eases moving existing apps
    • +Scales and replicates across nodes and regions

    Limitations

    • −YugabyteDB Anywhere, the management platform, is under the Polyform Free Trial License
    • −No separate entry in the 2026 Stack Overflow survey, so community data is thin
    • −More moving parts than a single PostgreSQL server

    SummaryYugabyteDB is the best choice for teams that need PostgreSQL-compatible SQL across regions because its Apache 2.0 core includes Raft replication, encryption at rest and change data capture. A single PostgreSQL server is simpler if you do not need distribution.

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