OSI-licensed open source
Database management software covers the engines that store and query data (a DBMS) and the tools used to administer them. Open-source options now cover relational, key-value, wide-column and analytical workloads, and several are the default choice for new projects.
This page lists OSI-licensed database engines (PostgreSQL, MariaDB, MySQL Community, Valkey, ClickHouse, Apache Cassandra, DuckDB) and two widely used administration clients (DBeaver, pgAdmin). Some popular databases use source-available licences and are mentioned in the FAQ, not listed.
Tools, licences and pricing checked against vendor and repository pages on November 7, 2026.
| Tool | Best for | Pricing | Licence |
|---|---|---|---|
| PostgreSQL | General-purpose relational workloads | Free, open source | PostgreSQL |
| MariaDB | MySQL-compatible workloads with community governance | Free, open source | GPL-2.0-only |
| MySQL Community Server | Established web application stacks | Free, open source | GPL-2.0-only |
| Valkey | Caching and real-time key-value workloads | Free, open source | BSD-3-Clause |
| ClickHouse | Fast analytical queries on large datasets | Free, open source | Apache-2.0 |
| Apache Cassandra | Large, always-on distributed workloads | Free, open source | Apache-2.0 |
| DuckDB | Embedded analytics and local data processing | Free, open source | MIT |
| DBeaver | Admin and querying across many databases | Free, open source | Apache-2.0 |
| pgAdmin | PostgreSQL administration | Free, open source | PostgreSQL |
Best for: General-purpose relational workloads · Free, open source
PostgreSQL is a mature open-source relational database. The GitHub repository mirrors the official Git repository, and its COPYRIGHT file contains the permissive PostgreSQL License.
Best for: MySQL-compatible workloads with community governance · Free, open source
MariaDB Server is a community-developed fork of MySQL, started by former core MySQL developers.
Best for: Established web application stacks · Free, open source
MySQL Server is a widely used open-source database. Its repository states the GPLv2 licence.
Best for: Caching and real-time key-value workloads · Free, open source
Valkey is a flexible distributed key-value database optimized for caching and other real-time workloads, under the BSD-3-Clause licence.
Best for: Fast analytical queries on large datasets · Free, open source
ClickHouse is a real-time analytics database management system under Apache-2.0.
Best for: Large, always-on distributed workloads · Free, open source
Apache Cassandra is an open-source transactional distributed database with linear scalability and fault tolerance on commodity hardware or cloud.
Best for: Embedded analytics and local data processing · Free, open source
DuckDB is a high-performance analytical database system, MIT licensed.
Best for: Admin and querying across many databases · Free, open source
DBeaver is a free universal database tool and SQL client for many database types.
Best for: PostgreSQL administration · Free, open source
pgAdmin is an open-source administration and development platform for PostgreSQL, released under the PostgreSQL licence.
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| If you need… | Start with |
|---|---|
| General-purpose relational | PostgreSQL, MariaDB, MySQL |
| Caching | Valkey |
| Analytics at scale | ClickHouse |
| Embedded analytics | DuckDB |
| Massive distributed writes | Apache Cassandra |
| GUI administration | DBeaver, pgAdmin |
Quick answers to common questions
PostgreSQL is a strong default for most applications because of its versatility and ecosystem.
MongoDB uses the SSPL, which the OSI does not recognise as open source, so it is excluded from this list.
A DBMS stores and serves data, while tools such as DBeaver and pgAdmin are clients used to administer and query one.
Both are GPLv2 and largely compatible. MariaDB is community governed; MySQL is owned by Oracle.
List it on TechLogHub and we'll review it for this guide.
