Semi-Stable Version

The latest semi-stable version is always here: - we don't call it a "release" because while it is more robust than the nightly build, it doesn't usually run through as many checks as a release would.

Nightly Builds

You can always grab the latest nightly build from Many users actually use this for their daily work.


Microsoft Windows

Double click on the jar file.

If this does not work, you probably need to install the Java Runtime

In more extensive edit sessions, you may get an "out of memory" error. To avoid this, the assigned memory can be increased.
Create a shortcut like in the following example:

C:\WINNT\system32\java.exe -jar -Xmx512M "C:\PATH-TO-JOSM\josm-latest.jar"

Linux / *BSD

using the shell
Go to the directory where the josm-latest.jar is and type
java -jar josm-latest.jar
to launch. Replace ''josm-latest.jar'' with the name of the jar file you loaded, e.G. josm.jar for releases.

If this doesn't help, try to set your JAVA_HOME variable to the java location (the root location, not the bin. As example:

 export JAVA_HOME=/usr/lib/sun-j2se5.0-jdk
 java -jar ''josm.jar''
There is a tutorial on how to setup your environment to start jar-files by clicking on them.
Right click on the JAR file, and select Open with "Sun Java 5.0 Runtime", or whatever java version you have.
Type this into a shell:
export AWT_TOOLKIT=MToolkit && java -jar josm-test.jar
as described here:
Blank window on startup

AWT before JDK7 doesn't play well with non-reparenting window managers (i.e. xmonad, awesome, dwm, ratpoison, Ion3, ...), resulting in the main window not being displayed properly on startup. The Awesome Wiki has workarounds for this problem. There is also an xmonad specific way of doing the wmname thing.


1.) If you have downloaded "josm-latest.jar" you can start JOSM by clicking on the josm-latest.jar file in the MacOS Finder (you might get the warning that you are about to open a file from the internet - just accept).

This way to start JOSM should be sufficient in most cases.

2.) However, if you need to start it up with additional Java parameter(s) (e.g. -Xmx512M) you can also use the MacOS "Terminal" and start JOSM (Java) manually:

Start the "Terminal" application (e.g. by typing "Terminal" into the Spotlight search)

Now you have two options:

a.) type in the following command and press "Enter" to start JOSM without any special java options (simply starts up JOSM like under point 1):

java -jar FOLDER/josm-latest.jar

Whereas "FOLDER" should be replaced by the name of the folder you have josm-latest.jar downloaded to. If you have downloaded it to the standard MacOS "Download" Folder it would look like:

java -jar Download/josm-latest.jar

b.) to use additional java options just add them right after "java"

If you for example have experienced the "Out of memory" warning (e.g. trying to load geo-tagged photos to JOSM) you would start JOSM like this:

java -Xmx256M -jar FOLDER/josm-latest.jar

This would allow JOSM to use up to 256 MB of RAM (memory). The java option "-Xmx256M" set's the maximum Java heap size to 265 MB. You are free to replace -Xmx256M by any number appropriate for your system (e.g. -Xmx512M or even -Xmx1024M).

By the way. To get an overview of all Java start options you can type in:

java -help

Getting the Source

JOSM is available under GPL, and so of course you can get the sources and compile, modify or redistribute it by yourself. You can grab the sources via subversion

svn co josm

Or you can inspect single files over the web frontend at


Using ant

The easiest way to compile JOSM provided Java on your machine is properly set up is to go to the josm directory and type:


That will create a dist/josm-custom.jar file if successful.

Using eclipse

Use eclipse and the provided .project and .classpath file. Just add a new Java Project using the JOSM source folder as existing path.

If you try to compile the JOSM sources in Eclipse and get errors like "The method marktr(String) is undefined for the type SomeType" look at solution suggested at mailing list.

There are also two Videos available at youtube, which show how to checkout JOSM into Eclipse and how to checkout a JOSM plugin into Eclipse.

Using javac

You can also build josm without ant or eclipse. To do so, call javac on the file org/openstreetmap/josm/gui/ with all libs from ../lib/*.jar in your classpath (you have to specify all subsequent). If running Linux, this would look like that:

  • Choose the right version of the java compiler (1.6)
$ sudo update-alternatives --config javac
        There are 2 choices for the alternative javac (providing /usr/bin/javac).

          Selection    Path                                   Priority   Status
        * 0            /usr/lib/jvm/java-6-sun/bin/javac       63        auto mode
          1            /usr/lib/jvm/java-1.5.0-sun/bin/javac   53        manual mode
          2            /usr/lib/jvm/java-6-sun/bin/javac       63        manual mode

        Press enter to keep the current choice[*], or type selection number: 1
        update-alternatives: using /usr/lib/jvm/java-1.5.0-sun/bin/javac to provide /usr/bin/javac (javac) in manual mode.
$ export JAVA_HOME=/usr/lib/jvm/java-6-sun

(Alternatively you can provide the full path when running javac.)

  • Check out the sources
$ svn co josm
        ''tons of output here''
$ cd josm/
$ mkdir build
  • Compile and run
    $ javac -cp .:src:lib/metadata-extractor-2.3.1-nosun.jar:lib/signpost-core-1.1.jar -d build src/org/openstreetmap/josm/gui/ 
    $ java -cp .:build:lib/metadata-extractor-2.3.1-nosun.jar:lib/signpost-core-1.1.jar org.openstreetmap.josm.gui.MainApplication
Last modified 4 years ago Last modified on 2014-03-22T09:33:47+01:00