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This page describes JMRI releases. Briefly, we have three kinds:
  • "Production releases" about twice a year. These are the ones we recommend to general users.
  • "Test releases", usually about monthly. These contain new features and changes that will eventually appear in the next production release.
  • Development builds, which are created every few hours as the developers update the code. You can download one of these if you want quick access to some particular fix, but please note that they're not fully tested. Test releases get more testing as part of the release process.
For more information on the (intended) release schedule, see the current list of milestones and the development roadmap.

If you've never installed a version of this program before, please read the installation guide (on the left) for your computer type and layout hardware. They will show you how to install the things that are needed before the program will run. These additional preliminary steps are one-time only and not necessary when updating. If you've previously installed a working version of the program, you only need to download and install one of the files listed below to update.

Installation guides: Windows, Mac OS X, Linux

See also the page of layout connections.

Latest News

Production release 4.20 available

On July 8, 2020 production release 4.20 was made available.

Release 4.20 is the current "production" release, recommended for first-time users. Please see the release note for additional information.

Test release 4.21.3 is available

Test release 4.21.3 was made available on December 18, 2020.

JMRI 4.21.3 is the next release of the current development series, containing the latest and greatest JMRI updates.

The series is working toward the next JMRI production release, probably in December 2020.

For more information, including the links to download a copy, please see the release note. Release 4.20 is the current "production" release, recommended for first-time users.

JMRI 4.20 - Production release

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Download:

Notes:

For more information on the release contents, please see the release note.

These files can be used for either a new installation or updating an existing installation.

We recommend that you verify the downloaded files using the provided sha256 key.

If you're looking to download Rodney Black's CATS application, see the CATS download page.

JMRI 3.10.1 - Production release for Java 1.6

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Release 3.10.1 is recommended for JMRI users with computers that can only run Java 1.6. Please see the release note for download and install information.

Production release 3.10.1 was made available onn January 11, 2015.

JMRI 2.14.1 - Production release for Java 1.5

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Release 2.14.1 is recommended for JMRI users with computers that can only run Java 1.5. Please see the release note for download and install information.

Production release 2.14.1 was made available on July 15, 2012.

JMRI - Test Releases

As the program develops, we also produce test releases. You may want to try these, as new features will show up in them first. They are announced in the JMRI users Groups.io group.

The most current test release is JMRI 4.21.3. More information on it, including the links to download a copy, can be found in release note.

For more information on the rough development schedule, please see the JMRI road map (which is only occasionally updated).

Related Items

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Java

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CATS
CATS

The Crandic Automated Traffic System (CATS) is a JMRI-based application by Rodney Black for controlling and operating a model railroad. There's more information on the CATS web site.

CATS 2.34 (Release2037) is compatible with JMRI 3.3.1 thru 3.8. We recommend that you use JMRI 3.8 with it.