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H2 Database Engine
H2 Database Engine · founded 2004
What it is
H2 Database Engine is a free SQL database written in Java, with embedded, server, and mixed operating modes. Databases can be stored on disk or kept in memory. It supports standard SQL and JDBC; server mode also accepts JDBC or ODBC connections over TCP/IP. A browser-based Console application includes autocomplete, while database features include transactions, multi-version concurrency, and row-level locking. Compatibility modes are listed for IBM DB2, Apache Derby, HSQLDB, MS SQL Server, MySQL, Oracle, and PostgreSQL. Database files can be encrypted with AES-128, and remote JDBC connections can use TLS. H2 is dual licensed under MPL 2.0 or EPL 1.0, and its license allows integration into and distribution with commercial applications. The maker describes the JAR file as around 2.5 MB and lists a Windows installer and an all-platforms ZIP. H2 cautions that it is not designed for adversarial environments and advises against exposing a server to untrusted connections. Its price is free.
For and against
For
- Supports embedded, server, and mixed modes.
- Offers disk-based and in-memory databases.
- Includes a browser Console with autocomplete.
- Database files can use AES-128 encryption.
- Commercial integration is permitted by its licenses.
Against
- Not designed for adversarial environments.
- H2 advises against exposing servers to untrusted connections.
The verdict
H2 combines multiple operating modes, common database interfaces, and compatibility options in a free Java database. Its security warning is important: the maker advises against exposing an H2 server to untrusted connections.
Who it suits
H2 suits developers who need a Java SQL database with embedded or server operation and standard SQL and JDBC support. Its compatibility modes may also suit projects working with the listed database systems.
Plans and prices
H2 Database Engine
Free to use for everybody · source code included
Read 2 Oct 2026 · h2database.com
On the record
- Compatibility
- Compatibility modes are listed for IBM DB2, Apache Derby, HSQLDB, MS SQL Server, MySQL, Oracle, and PostgreSQL.h2database.com · read 2 Oct 2026
- Database modes
- It supports embedded, server, and mixed modes, with disk based or in memory databases.h2database.com · read 2 Oct 2026
- Downloads
- The home page lists a Windows installer and an all platforms ZIP download.h2database.com · read 2 Oct 2026
- Encryption
- The feature list says database files can be encrypted with AES-128 and remote JDBC connections can use TLS.h2database.com · read 2 Oct 2026
- Footprint
- The home page describes a small footprint of around 2.5 MB for the JAR file.h2database.com · read 2 Oct 2026
- License
- H2 is dual licensed under MPL 2.0 or EPL 1.0, and the license page says it can be integrated into and distributed with commercial applications.h2database.com · read 2 Oct 2026
- Purpose
- H2 is a free SQL database written in Java.h2database.com · read 2 Oct 2026
- Security
- The security page warns that H2 is not designed for adversarial environments and advises against exposing an H2 server to untrusted connections.h2database.com · read 2 Oct 2026
- SQL and APIs
- H2 supports standard SQL and JDBC, and server mode supports JDBC or ODBC over TCP/IP.h2database.com · read 2 Oct 2026
- Support
- The home page directs users to Stack Overflow and a Google Group for support.h2database.com · read 2 Oct 2026
- Transactions
- The feature list includes transaction support, multi version concurrency, and row level locking.h2database.com · read 2 Oct 2026
- Web console
- H2 includes a browser based Console application with autocomplete.h2database.com · read 2 Oct 2026
