PostgreSQL is an object-relational database for applications that need SQL transactions, relational constraints and extensible data types. It also supports JSON documents and an extension ecosystem including geospatial tools. Teams can run it themselves or buy a managed service from a hosting provider; the database licence does not include somebody operating backups and upgrades for them. Learn more about PostgreSQL
Who should take a closer look?Application teams needing a relational foundation with flexible queries, document fields and extensions
Capabilities to explore
- ✓SQL transactions and relational constraints
- ✓JSON and JSONB data types
- ✓Custom functions and extensions
Free self-managed databasePostgreSQL is available without a licence fee under the PostgreSQL License. Hosting and operational support are separate.
MySQL is a relational database used behind websites and business applications. Community Edition provides a downloadable GPL database with transactions, replication and JSON support. Oracle also sells commercial editions and cloud services. A shortlist should identify the actual edition and application support requirement, rather than treating every product carrying the MySQL name as the same purchase. Learn more about MySQL
Who should take a closer look?Teams deploying applications already designed for the MySQL ecosystem
Capabilities to explore
- ✓SQL database and InnoDB transactions
- ✓Replication and high-availability tooling
- ✓Native JSON data type
Free Community EditionMySQL Community Edition is freely downloadable under GPL terms. This does not include paid Enterprise features or managed hosting.
MariaDB Server is a relational database originating from MySQL, with SQL access and its own development path. Community Server is GPLv2 software; commercial enterprise services are a separate offering. It is relevant for teams whose application or hosting stack supports MariaDB, but a modern MySQL migration needs version-specific checks for authentication, SQL behaviour and operational tooling. Learn more about MariaDB
Who should take a closer look?Teams choosing an established SQL engine for a MariaDB-compatible application or hosting stack
Capabilities to explore
- ✓Relational SQL database
- ✓Transactions and replication
- ✓Storage-engine and plugin options
Free Community ServerMariaDB Community Server is available under GPLv2. Infrastructure, commercial components and enterprise support are separate.
Microsoft SQL Server is a database platform with a T-SQL engine, administration tooling and editions for different workloads. It runs on supported Windows and Linux environments as well as cloud infrastructure. Express offers a limited free production route, while Developer editions are for non-production work. Choosing a deployment means checking the edition, operating environment and production licensing together. Learn more about Microsoft SQL Server
Who should take a closer look?Organisations running SQL Server applications and Microsoft-oriented database estates
Capabilities to explore
- ✓T-SQL relational database engine
- ✓Windows and Linux deployment options
- ✓Security and administration capabilities
Free Express editionExpress is free for eligible development and production workloads within its limits. Free Developer editions are licensed for development and testing only.
Oracle Database, currently presented as Oracle AI Database, supports established enterprise applications and SQL data workloads. The portfolio spans self-managed editions and Oracle cloud services. Oracle AI Database Free provides a limited local entry point, but it is not a supported production subscription. Existing application certification, operational skills and the exact licensed feature set are central buying considerations. Learn more about Oracle Database
Who should take a closer look?Organisations operating Oracle-certified applications or an established Oracle database estate
Capabilities to explore
- ✓SQL and PL/SQL application development
- ✓Relational and JSON data capabilities
- ✓Security and availability capabilities by edition
Resource-limited Free editionOracle AI Database Free is available without a subscription within its resource limits. It is unsupported and does not receive patches; Oracle recommends supported editions or services for production.
MongoDB is a document database that stores records as BSON documents and supports queries, aggregation and transactions. Teams can operate Community Server themselves or use MongoDB Atlas hosting. Its data model can suit applications organised around documents, while schema validation, indexes and cross-document requirements still need deliberate design. Atlas Free is a constrained development entry point rather than a promise of unlimited production hosting. Learn more about MongoDB
Who should take a closer look?Application teams with document-oriented data and a clear plan for queries and indexing
Capabilities to explore
- ✓Document-oriented BSON storage
- ✓Query and aggregation pipelines
- ✓Indexes and schema validation
Atlas Free and Community ServerAtlas Free clusters do not expire but have limited scale and capabilities. Self-managed Community Server is available under SSPL terms.
Redis provides an in-memory data platform used for caching, application state and data structures such as streams and sorted sets. Redis Open Source, Redis Cloud and Redis Software are separate deployment and commercial choices. Version 8 and later offer an AGPLv3 licence option alongside RSALv2 and SSPLv1; older releases have different terms. Persistence and failover should be designed around what the application can afford to lose. Learn more about Redis
Who should take a closer look?Engineering teams designing caching, session state, queues or specialised data-access layers
Capabilities to explore
- ✓In-memory key and data-structure access
- ✓Streams, sets and sorted sets
- ✓Persistence and replication options
Self-managed Open Source optionRedis Open Source 8 and later can be used under AGPLv3, RSALv2 or SSPLv1 terms. This free software option does not include infrastructure or commercial support.
SQLite is an embedded SQL database library that reads and writes database files within an application process. It avoids running a separate database server and is well suited to local application storage, mobile applications and many single-node workloads. Its public-domain core is free to use, while a team still needs to design file access, backup handling and the expected pattern of concurrent writes. Learn more about SQLite
Who should take a closer look?Developers needing local, embedded or straightforward single-node SQL storage
Capabilities to explore
- ✓Embedded SQL database library
- ✓Transactional single-file databases
- ✓No separate server process
Free embedded databaseSQLite's deliverable code is dedicated to the public domain. It runs inside the application rather than as a hosted free-plan service.
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