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Wisser/Jailer

Free Java tool for creating referentially intact subsets of production databases and browsing data along its foreign-key relationships.

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What is it?

Jailer extracts small, consistent slices of a relational database and exports them as topologically sorted SQL, JSON, YAML, XML or DbUnit records. This makes it practical to build small test datasets from production data, or to pull only the relevant rows for local troubleshooting while keeping foreign-key integrity intact.

It also includes a Data Browser that navigates the database in both directions, following foreign keys or user-defined relationships, and an SQL Console with code completion, syntax highlighting, charts and pivot tables. Recent versions add AI assistants that generate subset definitions, produce SQL from natural language questions, and analyze or refactor existing queries, using Anthropic or OpenAI-compatible APIs.

Jailer works with any database that has a JDBC driver and has dedicated support for PostgreSQL, Oracle, MySQL, MariaDB, SQL Server, Db2, SQLite and several others. It is distributed as a desktop GUI installer for Windows and Linux, a zip for other platforms with Java, and a command line interface and Maven-published engine for programmatic use.

Key features

  • 01Exports referentially intact row sets as topologically sorted SQL DML, JSON, YAML, XML or DbUnit.
  • 02Data Browser for navigating tables bidirectionally via foreign keys or user-defined relationships.
  • 03SQL Console with code completion, syntax highlighting, charts and pivot tables.
  • 04AI assistants for generating subset definitions and SQL from natural language.
  • 05Includes a demo database for trying the tool without configuration.
  • 06Programmatic API and command line interface for automating exports.

Use cases

  • Creating small, realistic test datasets from a production database.
  • Copying only the relevant rows of production data into a development environment for debugging.
  • Archiving and removing obsolete data without breaking foreign-key constraints.
  • Exploring unfamiliar database schemas by following relationships between tables.

Quick start

  1. 1

    Download the Windows (.msi) or Linux (.deb) installer from the latest release, or the zip for other platforms with Java

  2. 2

    Start Jailer and open the included demo database, which needs no configuration

  3. 3

    Connect to your own database and start the Data Browser or the Subsetter

Things to know

  • The AI query and subsetting features need an API key from Anthropic or an OpenAI-compatible provider.

In collections

Databases & SQL tools

Topics

#database#subsetting#jdbc#sql#test-data#data-browser#java#data-export#db2#export

FAQ

What is Jailer?
Free Java tool for creating referentially intact subsets of production databases and browsing data along its foreign-key relationships. Jailer extracts small, consistent slices of a relational database and exports them as topologically sorted SQL, JSON, YAML, XML or DbUnit records. This makes it practical to build small test datasets from production data, or to pull only the relevant rows for local troubleshooting while keeping foreign-key integrity intact.
Is Jailer free to use? What license does it have?
Jailer is open source under the Apache-2.0 license. Check the license terms before using it in commercial products.
Is Jailer still maintained?
Actively maintained. The last commit to Jailer was on Nov 6, 2026.
What can I use Jailer for?
Creating small, realistic test datasets from a production database. Copying only the relevant rows of production data into a development environment for debugging. Archiving and removing obsolete data without breaking foreign-key constraints. Exploring unfamiliar database schemas by following relationships between tables.
How do I install Jailer?
Download the Windows (.msi) or Linux (.deb) installer from the latest release, or the zip for other platforms with Java Start Jailer and open the included demo database, which needs no configuration Connect to your own database and start the Data Browser or the Subsetter
Where can I get Jailer?
The source code and installation instructions are on GitHub: https://github.com/Wisser/Jailer

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