OS Independent Web Start Windows Mac OS X Ubuntu, … openSUSE
tested 10526 jar jnlp setup.exe (portable) see below see below
latest 10619 jar jnlp see below
older download/
  • Which version should I use? (see also: release system)
    • tested is released approx. monthly and shouldn't contain severe bugs
    • latest is released daily, may have more errors
    • If possible, use the Web Start version in order to automatically update.
  • Verify josm.jar with jarsigner

  • Note that there are fairly regular updates, so always try running a recent version (and also recent plugins).
  • Access JOSM-WebStart without installation
  • Download the tested JOSM version 10526
  • Download the Windows JOSM installer version 10526
  • Download the Mac OS X JOSM package version 10526
  • Prepare a USB flash drive to use JOSM on any foreign Windows machine.
  • For download scripts use version check for latest and tested (or both) to reduce download bandwith
  • If download size is an issue for you:
    • Append ?lang=… to the download link address for both releases to strip unused translations (e.g. ?lang=de will download JOSM in German language only).
    • Note: Use underscore to separate language codes with country code extensions, e.g. ?lang=en_GB
    • Append ?unsigned=1 to strip the code signing information
    • When lang and unsigned are used the separation is a & sign like in ?lang=de&unsigned=1

Mac OS X errors

OS X "gatekeeper" results in this very misleading error dialog Since Mac OS 10.8 a error message may appear on your first attempt to run JOSM:

  • older versions: is damaged and can't be opened. You should move it to the Trash.
  • newer versions: can't be opened because it is from an unidentified developer.

To open JOSM for the first time, right-click on and confirm the opening in the pop-up dialogs. This is only necessary on the first run of JOSM.

Development Version

  • Download the latest JOSM version 10619 (may have more errors than "tested", be careful with this one).


  • Get the source:
    • From the official Subversion repository (recommended if you're interested in JOSM core only):
      svn co josm
    • From the official OSM Subversion repository (recommended if you're also interested in plugins):
      svn co
    • From the unofficial GitHub mirror:
      git clone git://
  • Or you can inspect single files over the web frontend at svn (or browser).

openSUSE repository

Tested version of JOSM is available in the Application:Geo repository.

First add as root user in yast or with zypper the repository (replace the version in the URL with the one you are using):

zypper ar -f Application:Geo

Then simply install josm and josm-fonts package.

Ubuntu repository

This is a package repository primarily for Ubuntu. It should also work with other Debian based (especially Ubuntu based) distributions, but we do not actively test and maintain any distributions other than Ubuntu.
Note: in addition to the regular procedure described below, older DEBs can be manually downloaded and clicked to be installed from the following directories: for josm for josm-latest

The repository contains two packages:

The tested version
Replaces the package from the official Ubuntu repository.
The development version (nightly build)
Can be installed parallel to the josm package. The default preference folder is ~/.josm-latest.


Edit the package resource list /etc/apt/sources.list:

sudo editor /etc/apt/sources.list

and add one of the following lines according to your Ubuntu-Version:

deb lucid universe
deb precise universe
deb quantal universe
deb raring universe
deb saucy universe
deb trusty universe
deb utopic universe
deb vivid universe
deb wily universe
deb xenial universe

Alternatively, this can be done with the following one-liner:

echo deb $(lsb_release -sc) universe | sudo tee /etc/apt/sources.list.d/josm.list > /dev/null

For other Debian based distributions, add the following line:

deb alldist universe

Download and register the public key:

wget -q -O- | sudo apt-key add -

Now refresh your sources

sudo apt-get update

and install:

(You can skip the first line if you haven't installed these packages before.)

sudo apt-get remove josm josm-plugins
sudo apt-get install josm
sudo apt-get install josm-latest

Increase memory given to a JOSM

If JOSM runs out of memory, you can increase the maximum size of allocated memory (400 MB in this example):

JAVA_OPTS="-Xmx400M" josm

Start with a different preference folder:

JAVA_OPTS="-Djosm.home=$HOME/.josm-tmp" josm

VM selection on Windows x64

For Windows, beware that some browsers may install their own JRE only in 32 bit mode, but may also install their version of the Javawebstart tool somewhere else with different file associations. This may cause your JNLP to start with this alternate JRE because it runs the wrong version of Javawebstart which only supports the 32 bit VM, and sometimes is built with a restricted support for VM options and a max VM size not exceeding 256MB.

Check, for example, if there's no other javawebstart in \Windows\SysWow64. You should not need it (the Java control panel will not detect it) and can safely delete it. Perfom cleanup and only keep the latest version of the JRE (1 for the 32-bit mode, another one for the 64-bit mode).

For shortcuts created on the desktop for JNLP and running the Javawebstart launcher (from \windows\system32), make sure to pass VM parameters prefixed with -J and no intermediate space before the VM option. If you have installed both the 32-bit and 64-bit version, you should pass the option "-d64" if you want to select the preferred 64-bit VM. Note that some Oracle documentation pages indicate the option "-D64" with the incorrect capitalization!)

Example of an edited commandline for the shortcut created on the windows desktop after running JOSM just once from the JNMP and exiting:

C:\Windows\System32\javaws.exe -J-d64 -Xmx=2048m -localfile -J-Djnlp.application.href= "C:\Users\<snipped user name>\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\21\7311<snipped-hex-number>7f8"

You don't need to change the end of the command line with the snipped parts here. Just check the path for javaws.exe and add options -J-d64 for the 64-bit mode needed to work with large OSM datasets, and -Xmx=2048m to increase the VM size (to 2GB here).

Last modified 6 weeks ago Last modified on 2016-06-13T14:59:41+02:00

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