Installing and Running the CalTopo Desktop App - Windows

NOTE: These instructions do not apply to mobile devices and is desktop software is not required for use on a mobile device. See mobile download instructions at:

To install the CalTopo Offline App you will need:

  • CalTopo App
  • CalTopo map data for your desired area
  • Java Standard Edition JDK

Installation Instructions

  1. Download and install the CalTopo app

    Decide whether you want to install CalTopo Offline on your computer's hard drive, a thumb drive or an external hard drive. Depending on how much map data you plan to download, it may not fit on your computer's hard drive. If you're not sure, start by installing it to your computer's hard drive now, it can be copied to another drive later if needed.

    Sign-in to your offline account on

    Click on your account name at the top of the left bar, then the "Offline Access" tab, or go directly to

    Click on "fresh install" and download the file to your computer.


    In File Explorer, go to the Downloads folder and right-click "" and click "Extract All".


    Specify the drive where you want to install CalTopo (e.g. "C:\") and click "Extract"


  2. Install Java Standard Edition JDK
    Go to Click on "Download" under "JDK."

    To download the installation file, cllick "Accept License Agreement" and choose the appropriate JDK for your Windows Operating System.

    Once the installation file is downloaded, open it to run it. Accept all of the default installation options.

  3. Download the map data.

    CalTopo Offline is installed without any map tiles, but includes a map downloader. To download map tiles for your desired area, follow the"Running CalTopo Offline" instructions below and then see the downloader documentation.

Running CalTopo Offline

CalTopo Offline is essentially the same program as Whereas is hosted by a web server in the Internet cloud, CalTopo Offline is hosted by a local web server on your computer. In both cases you use a web browser to interact with the server.

Therefore it takes two steps to run CalTopo Offline:

  1. Start the CalTopo Offline server:

    In File Explorer, open the "caltopo" folder (eg c:/caltopo). If you have Java version 9 installed, double-click on the "CalTopo-Offline-Java-9" file, otherwise double-click on the "CalTopo-Offiline" file.


    You should see a black command window open.


    You can minimize this window, but don't close it. The server is now started and you can go to a browser to access the functionality.

  2. Open a web browser (Chrome is recommended). On a new tab, go to http://localhost:8080.


    The server may take some time to get up and running. If initially you get a web page error (e.g. a “This webpage is not available” or "This site can’t be reached" message), then the local web server may need more time to get fully started. Wait for a few seconds and refresh the page.

    The first time you bring up the CalTopo Offline server, or after updating Java, you may get a Windows Firewall message.


    Click "Private networks" and "Allow Access" to allow the CalTopo Offline webpage to talk to the CalTopo Offline server on private networks (to include on your own computer).

Stopping the CalTopo Offline server

When you are finished using CalTopo Offline:

  1. Close the CalTopo Offline tab in your browser
  2. Click on the black command window that opened when you started the CalTopo Offline server and click the "X" to close it.


Accessing the CalTopo Offline server from another computer

If multiple computers are on the same Local Area Network (e.g. connected to the same router), each of the computers can connect to the CalTopo Offline server running on one of the computers. To do so, each computer opens an web browser and goes to the Server Address displayed in the black command window (eg. http://mycomputer:8080) for the CalTopo Offline Server.

Updating CalTopo Offline to a New Version

To update your version of CalTopo Offline, download a new version of the cal.jar file to your caltopo folder.

to your offline account on

Click on your account name at the top of the left bar, then the "Offline Access" tab, or go directly to


Click on "JAR only" and move the cal.jar file from your Downloads folder to your caltopo folder.