Sounder: Offline Field Maps
Topo, charts, tracks & layers
Only for iPhone
Free · Designed for iPhone. Not verified for macOS.
iPhone
Topo, satellite, radar and river charts in one stack you control. Record tracks, navigate to waypoints by compass, and add any map layer from a URL or a file.
Sounder is a map for people who spend their time outdoors: trails and two-tracks, back forties, rivers and marshes. Stack as many maps as you want, fade one over another, record where you went, and mark what you found. Then add your own maps: Sounder reads the open formats everyone else publishes in.
MAPS
• USGS topo, imagery and shaded relief, and live 3DEP hillshade
• NWS weather radar, refreshed every five minutes
• NOAA nautical charts and Corps of Engineers inland river charts
• The Forest Service basemap and motor vehicle use maps
• Any number of layers at once: the bottom one is the base, and every layer above it gets its own opacity slider
YOUR OWN LAYERS
• Add a layer from a URL: paste an ArcGIS map or image service, a WMS, XYZ / TMS tiles, TileJSON, or PMTiles
• Open MBTiles and PMTiles files for fully offline maps, raster or vector
• Subscribe to layer catalogs: a JSON file anyone can host that lists layers and offline packs
• Tap a vector layer to see what's under your finger
TRACKS AND WAYPOINTS
• Record tracks, including with the screen off
• Waypoints with icons, notes and photos; draw areas
• Go To any waypoint or any spot you tap: a pointer that swings toward it as you turn, with distance and bearing
• Heading-up map that steers by compass on foot and by GPS course once you're moving
• Import GPX, KML, KMZ and GeoJSON, including exports from other mapping apps
• Export everything as GPX
OFFLINE AND SAFE
• Download any area for use with no signal: frame it on the map, pick the layers and the detail, and see the size before you start
• Downloaded areas load instantly with one bar of signal, too
• Live layers like radar are never saved, so an old picture can't pass for a current one
• Automatic backups to your own iCloud Drive, with 30 days of daily snapshots and a GPX copy any app can read
PRIVATE
No account, no ads, no tracking, no analytics. Your location and everything you save stay on your phone and in your own iCloud.
Map data comes from public agencies and from sources you add, and may be out of date or wrong. Use it alongside official charts, posted signs and your own judgment.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Jason Dostal, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Jason Dostal
- Size
- 11.9 MB
- Category
- Navigation
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.
- iPhone
- Location
- This app may use your location even when it isn’t open, which can decrease device battery life.
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Jason Dostal