Backcountry Mapping Evolved

The CalTopo Blog helps provide documentation for new features.

CalTopo supports many of the features provided by desktop topo software, but because it's online, you can view your data from anywhere and share it with anyone. It also adds a lot of new features to the mix, like layer blending, slope shading and historical maps. Data is not guaranteed correct, think twice before walking off a cliff!

I'm Matt Jacobs, I wanted to develop better maps and mapping tools for Search and Rescue. I created a program called Sarsoft, and after some trial and error I built out a few seamless map layers for California. I put the map viewer from Sarsoft online so that people could check out my maps and play with cool features like layer blending; it only covered California, so the name seemed logical. Since then I've expanded coverage to all 50 states and grown the site significantly, but haven't had any luck changing the name. If you like CalTopo, consider giving Bay Area Mountain Rescue a tax-deductible donation. Donations don't benefit me directly, but they do finance important gear for the team that helps me save lives. And since I dream of someday finding a way to make a part time living off CalTopo, I'd feel bad asking for donations and then charging for features.

CalTopo has taken too many of my nights and weekends, when I should have been out skiing, climbing, drinking or otherwise enjoying life. Like it or hate it, feedback or flame mail, I'd love to hear from users. Email me at

Help Videos

Map Layers

The CalTopo experience begins with mixing and matching map layers. From simple shaded relief to complex stacks involving contours and aerial imagery, layer blending makes for beautiful visualizations and new ways of looking at terrain. To play with this, simply click on the +0 or +1 at the top right of the screen, which shows the current number of additional layers - or click on one of the presets in the leftbar. The images below are just examples to get you started - click on one to view the actual map.

High Resolution Topo Scans

Forest Service Road and Boundary Maps

GPS-Compatible Visitor Maps

Historic Topos

Relief Shaded, Contoured Imagery

US Topo Aerial Maps

Slope Shading

Custom DEM Shading

Creating and Editing Shapes

CalTopo allows you to add markers, lines and polygons to a map. Either right-click on the map background, or look for the + Add New Object menu in the leftbar.

Markers are GPS waypoints combined with an image icon. You can choose from a set of existing images, supply your own custom URL or enter an RGB hexidecimal color code. When you first create a marker it will be placed in either the center of the screen, or the location you right-clicked to bring up the context menu. Clicking a marker's edit icon in the leftbar allows you to both drag it to a new location and alter its label and icon.

Unlike GPS units, CalTopo doesn't differentiate between routes and tracks. Instead it provides two kinds of shapes: lines, which are essentially stylized routes, and polygons. When creating a shape, the following actions are available:

clickadd a new point
shift-mousedownadd freehand points (line follows the cursor in a smooth fasion)
double clickfinish
When editing an existing shape, circular drag handles are placed at each vertex and midway along each segment. Use these to modify vertex locations or add new vertices; right-clicking on a drag handle allows you to delete an existing vertex.

Saving and Sharing

There are a number of ways to save your data and share it with others.

Plain MapMaps without any shapes or markers can be shared or bookmarked as a self-contained URL. CalTopo will automatically update the map viewer's URL for you; it will look something like /map.html#37.743,-119.578&z=14&b=t. If this is turned off, look for the Share link in the leftbar.
Unsaved MapOnce you've added data, the URL alone doesn't suffice: you'll need to save it. There are three ways to do this, listed below. All start with the Save link.
Saved to Your AccountOnce you save a map to your Yahoo or Google account, all future changes will be automatically synced to CalTopo - no need to hit save before closing your browser. Using an existing account means one less password to remember; CalTopo does not gain any access to your Yahoo/Google account. Once saved, you can limit access and provide a password for friends to make edits through the Share link.
One Off MapA one-off map lets you save data without logging in, and post a permanent link on a forum without cluttering your account. You can enter a password for write access, or if you're already logged in when the map is saved, your account will continue to be able to make edits.
Browser MapYou can also save maps directly to your browser; because these are not backed up to CalTopo, you can't share them with anyone. However, when used alongside cached maps from CalTopo To Go, they allow you to make edits offline, in places without internet access.

Importing and Exporting

CalTopo can transfer data to and from GPX files, KML files and Garmin GPSs. Because not everything provided by CalTopo is supported by these formats (and vice versa), some things may get lost in translation. GPS routes and tracks will both become lines. Advanced KML features like superoverlays and multi-ring polygons will be ignored. When exported to a GPX file, polygons will become simple lines.

To transfer data, simply look for the Import and Export links near the top of the leftbar. GPX and KML work through simple file transfer; in order to communicate directly with a Garmin GPS, you'll need to install their Communicator browser plug-in.

Although GPX files don't speak colors and icons, CalTopo stores that information in the GPX file's metadata and can read it on import. If you want to copy markers or shapes from one map to another, export them to GPX and then re-import them into the new map. Line weight, color, icons and polygonality will all be preserved.


There are two ways to get your maps onto paper: printing through the browser, and using CalTopo's PDF generator. The PDF generator produces high-resolution, exact-scale maps, and makes it easy to produce multi-page map packs. Unfortunately we can only use it to print maps under CalTopo's control, so it doesn't work with Google's maps and a few other layers. For all printing options, look for the Print icon in the top right.

The PDF generator produces maps with more than twice the resolution of browser printing. That means it needs 4 times as many map tiles, and downloading all those tiles can take a while. Please be patient, it really is working hard.

Google Earth Integration

Pull CalTopo maps into Google Earth! Look for the KML link in the left bar.

Superoverlays give you nationwide coverage from a single file. As you fly around, Earth pulls additional superoverlay files from CalTopo as needed. Due to the number of tile requests this can generate, only single layers are supported. Try it out with USGS Topos and Forest Service Maps.

KML and KMZ files only cover a limited area, but you can combine layers CalTopo style. Pick a zoom level, drag the rectangle onto the area you want to cover, hit download and grab a beer - that was some hard work!

Offline Access

You can take maps with you for offline, internet-free use with CalTopo To Go. This service pre-saves map layers to your browser using HTML5 Application Caching so that they're ready to go when you hit the road. Start by visiting the To Go page, choose the layers and geographic area you want coverage for, and then click 'Take This To Go'. Make sure to copy maps from your account to your browser for full on-the-road editing capabilities.