Offline-first field mapping platform

Mapping that works
without the network

ZYRN TOPO is an offline-first topographic mapping and team-coordination platform for field operations — 0.7.9 brings a redesigned Settings screen, on top of a refreshed enterprise-grade interface, a live weather widget, elevation profiles, averaged survey waypoints, an on-screen UTM/MGRS grid, use-any-map-as-an-overlay, and field-data overlays (PLSS survey grid, USFS roads/trails, wetlands, contours, watersheds, weather radar, and active wildfire perimeters), plus a current Android beta APK for sideload testing.

Get the app Start Mapping Free
Download Beta APK Support Development
ZYRN TOPO running on a mobile device
Trusted data & standards
USGS Esri ArcGIS OpenStreetMap Mapterhorn DEM BLM / USFS Reticulum Mesh MAVLink / ATAK CoT CalTopo-compatible GeoJSON
01

Designed for field operations

Teams depend on ZYRN TOPO where connectivity is unreliable or absent — search-and-rescue, field research, and resource management that cannot afford to lose the map when the network drops.

Backcountry & Expedition

Route planning, GPS tracking, 3D terrain, and slope-angle analysis that remain fully available outside network coverage.

Public Lands & Resource Management

BLM and USFS boundary overlays, land-status reference, and durable on-device basemaps for work beyond the road network.

Field & Survey Teams

Precise positions in DD, DMS, DDM, UTM, and MGRS, track recording, point elevation, and complete on-device map coverage for remote sites.

Search & Rescue

Assign operational periods, draw search areas, record tracks, and coordinate field units in real time over P2P, LAN, or radio mesh — with no cellular dependency.

Operational reliability

Engineered to run where infrastructure doesn't

ZYRN TOPO has no backend. Map data, objects, and tile archives are stored locally on the device — nothing to provision, nothing to authenticate against, and no recurring cost.

Offline-first architecture

Map tiles, objects, and PMTiles archives are stored on-device in OPFS and IndexedDB. The cache pass adds bounded preloading, parent-tile fallback, persistent-storage requests, and reconnect re-warming so maps feel smoother online and offline.

Data ownership by design

All data stays on the device — no telemetry, no analytics, no third-party processing. A single purchase covers Android and the web application, including every future release.

Multi-transport team synchronization

Coordinate teams over WebRTC P2P, local LAN, Reticulum LoRa mesh, and MAVLink telemetry, with a bidirectional ATAK CoT bridge. Redundant transports keep units in sync across any operating environment.

23
Base map layers
15
Map overlays
1,345+
Imagery sources
5
Sync transports
02

Core capabilities

A complete operational toolset — mapping, 3D terrain, positioning, drawing, offline storage, data interchange, and team synchronization — engineered to function without network connectivity.

23 Base Layers

  • 10 no-key vector basemaps — smooth at any zoom
  • OFM Liberty · Bright · Positron · Dark · Fiord
  • VersaTiles Colorful · Neutrino · Graybeard · Eclipse · Shadow
  • USGS Topo & Imagery+Topo · OpenTopoMap
  • NatGeo · Esri World Topo · USA Topo · Esri Physical
  • Esri Satellite · USGS Imagery · Esri Ocean (bathymetric)
  • OpenStreetMap · OSM Humanitarian · CyclOSM
  • High-resolution zoom — satellite to z21, deep tiles where available

3D Terrain — On-Device

  • MapLibre GL JS WebGL rendering
  • Real DEM elevation (Mapterhorn Terrarium)
  • Save Terrain → DEM PMTiles stored locally
  • 3D mode works without network after save
  • Drapes any base layer over the mesh
  • Pitch, rotation, and zoom controls

15 Overlays

  • Slope-angle shading · Hillshade
  • USGS Topo & Hydrography
  • Boundaries · Transportation · Esri Reference Labels
  • Hiking · Cycling · MTB (Waymarked)
  • OpenSnowMap pistes · OpenRailwayMap
  • OpenInfraMap power · BLM Public Lands · OpenSeaMap
  • Stack & reorder — front-to-back, per-layer opacity

Shaded Relief

  • Normal, Enhanced, and Terrain modes
  • Adjustable overlay opacity
  • Per-overlay opacity control
  • Right slide-out Map Layers panel
  • Night mode toggle

Custom Sources + Imagery Catalog

  • Add WMS / WMTS tile services
  • Add WFS vector feature services
  • Browse 1,345-source imagery catalog
  • (OSM Editor Layer Index, filter by country/type)
  • One-tap add to your layers · persisted

Vector PMTiles

  • Import OpenFreeMap / Protomaps vector tiles
  • MapLibre addProtocol('pmtiles') rendering
  • Auto-generated style from vector_layers metadata
  • Drapes over locally stored DEM terrain
  • Raster + vector PMTiles supported

Map Controls

  • Compass rose with heading-up mode
  • Map rotation support (leaflet-rotate)
  • Infinite world wrap — markers & GPS carry across copies
  • Center crosshair · coordinate display (5 formats)
  • Context menu on long-press

Markers & Waypoints

  • Drop markers at any location or GPS
  • Custom name, notes, and color
  • 50+ pin icon types
  • Tap marker for info/edit/navigate
  • Photo waypoints from camera

Lines & Polygons

  • Draw lines on map with tap or freehand
  • Draw polygon areas
  • Custom color per object
  • Buffer zones and range rings
  • Sector/wedge drawing

Folders & Organization

  • Create folders to group objects
  • Assign objects to folders
  • Toggle folder visibility on map
  • Search and filter map items
  • Object context menu (edit/delete/move)

Operational Periods

  • SAR-style operational period management
  • Custom name, color, and thickness
  • Toggle period visibility
  • Assign objects to periods
  • Period-based filtering

Team Members

  • Add team members with roles
  • Contact info and status
  • Import/export team as CSV or JSON
  • Team management panel
  • Assign members to operations

Gear / Pack List

  • Full gear inventory management
  • Weight tracking per item
  • Category organization
  • Import/export gear as CSV or JSON
  • Pack weight summary

GPS Location

  • Real-time GPS with live position
  • 3-state center: off → follow → heading-up
  • GPS accuracy circle on map
  • Drop marker at current GPS
  • Navigate to any point

Track Recording

  • Start / stop track recording
  • Live distance, time, and speed
  • Track polyline drawn on map
  • Save recorded tracks as objects
  • Track bar with live stats

Measure Tools

  • Point-to-point distance measurement
  • Area measurement for polygons
  • Bearing / heading between points
  • Elevation profile along path
  • Live measurement display

Navigation

  • Navigate to any marker or search result
  • Bearing and distance to target
  • Navigation bar with live updates
  • Stop navigation button
  • Works without a signal

Search

  • Nominatim geocoding search
  • Search by place name or coordinates
  • Jump to any location on map
  • Search results as markers
  • Coordinate paste support

Point Info

  • Tap anywhere for elevation data
  • Coordinates in DD, DMS, DDM, UTM, MGRS
  • Weather data from NWS forecast
  • Point info floating panel
  • Copy coordinates to clipboard

Drawing Tools

  • Lines, polygons, and freehand drawing
  • Buffer zones around objects
  • Range rings (concentric circles)
  • Sector/wedge shapes
  • Drawing status pill with undo

Color Picker

  • Full color picker for every object
  • Preset color grid
  • Applied to markers, lines, polygons
  • Color persistence across saves
  • Visual color preview

Print to PDF

  • True-scale cartographic PDF sheets
  • Vector and raster basemap support
  • Online and offline tile rendering
  • High-resolution output with grids and marginalia
  • Cleaner marker and label rendering

Night Mode

  • 3-state cycle: off → dim → dark
  • CSS filter-based map dimming
  • Preserves UI readability
  • Quick toggle from layers panel
  • Separate from base layer choice

Settings

  • Coordinate format selection (5 types)
  • Default base layer choice
  • GPS accuracy preferences
  • Unit system selection
  • Permission management

Weather

  • NWS forecast for any US location
  • Temperature, wind, conditions
  • Forecast period display
  • Accessed via point info panel
  • Works at any tapped coordinate

PMTiles Tile Archives

  • Real .pmtiles files stored on device
  • Streamed to OPFS — no eviction
  • Import any PMTiles archive
  • Raster and vector archives supported
  • Survives storage pressure

Area Saver

  • Draw a box on the map — drag & resize to frame any area
  • Or save the current view, or pick a preset region
  • Any zoom range · works for raster and vector bases
  • Background downloads — resume after app restart
  • Streams direct to OPFS (multi-GB safe) · SHA-1 dedup

Local-First Architecture

  • Origin Private File System (OPFS)
  • Service Worker fallback for network tiles
  • Bounded viewport and zoom preloading
  • Cached parent-tile fallback while offline
  • Network reconnect redraw and re-warm

Storage Management

  • Per-archive bounds + zoom range listed
  • Remove individual tile archives
  • Total disk usage display
  • Bundled vs imported clearly marked
  • Map objects untouched by archive ops

3D Terrain On-Device

  • Save Terrain packs Mapterhorn DEM into a PMTiles archive
  • Tagged kind: 'dem' — auto-used when 3D engages
  • z0–10 default; covers a city in ~50 MB
  • 3D mode works without network after save
  • Falls back to network when no local DEM

Data Security

  • All data stays on your device
  • No telemetry or analytics
  • No account required
  • Export/import for backup
  • Your data, your device

Export

  • GeoJSON with CalTopo simplestyle (round-trip)
  • GPX 1.1 with gpx_style colors (Gaia, Garmin)
  • KML / KMZ for Google Earth
  • CSV for spreadsheets
  • Print to PDF

Import

  • GeoJSON import with merge
  • KML/KMZ file import
  • GPX track and waypoint import
  • CSV data import
  • Drag-and-drop support

Persistence

  • Auto-save to localForage (IndexedDB)
  • Map title saved with data
  • Settings saved separately
  • Survives app close and restart
  • Multiple save slots via export

Gear Import/Export

  • Export gear list as JSON
  • Export gear list as CSV
  • Import gear from file
  • Weight and category preserved
  • Bulk gear management

Team Import/Export

  • Export team roster as JSON
  • Export team roster as CSV
  • Import team from file
  • Roles and contact info preserved
  • Share team configs

Local Storage

  • IndexedDB via localForage
  • Cache API for map tiles
  • No cloud dependency
  • Works fully air-gapped
  • Persistent across updates

P2P Mesh (Trystero)

  • WebRTC peer-to-peer via Nostr relay
  • No server required — share a session code
  • Live peer location circles on map
  • Encrypted, end-to-end data channel
  • Team chat + map object sharing

LAN Hub (relay.mjs)

  • Node.js WebSocket relay server
  • All devices connect to one LAN IP
  • Works with zero internet access
  • QR code for easy device onboarding
  • Includes built-in ATAK CoT bridge

Reticulum & LXMF

  • Long-range mesh — LoRa, serial, or TCP
  • Add devices by 32-hex LXMF address
  • Sideband-compatible (announce + messaging)
  • Persistent identity across restarts
  • Bridge runs on any computer on your network

Drone Telemetry (MAVLink)

  • MAVLink v1/v2 binary parsing
  • Live drone position on map
  • Battery, flight mode, and altitude
  • HEARTBEAT, SYS_STATUS, GPS_INT
  • Connect via WebSocket or TCP bridge

ATAK CoT Bridge

  • Bidirectional CoT — your team appears on ATAK
  • UDP multicast 239.2.3.1:6969, CoT types a-f / a-h / a-n
  • Incoming CoT detection events displayed as map markers
  • Marker color follows CoT type (friendly · neutral · hostile)
  • 120 s stale timeout; Python bridge runs on any networked computer
03

Map data and coverage

23 base layers, 15 analytical overlays, and a catalog of 1,345 imagery sources. Any region — including 3D terrain elevation — can be stored as a local .pmtiles archive with no eviction and no cache dependency.

USGS Topo
Topo
USGS Topo
USGS Imagery + Topo
Topo
USGS Imagery + Topo
OpenTopoMap
Topo
OpenTopoMap
NatGeo World
Topo
NatGeo World
Esri World Topo
Topo
Esri World Topo
USA Topo
Topo
USA Topo (Historical)
Esri Satellite
Imagery
Esri Satellite
USGS Imagery
Imagery
USGS Imagery
OpenStreetMap
Street
OpenStreetMap
Humanitarian
Street
OSM Humanitarian
CyclOSM
Street
CyclOSM
Esri Physical
Topo
Esri World Physical
Ocean
Water
Esri Ocean Basemap
OFM Liberty
Vector
OFM Liberty
OFM Bright
Vector
OFM Bright
OFM Positron
Vector
OFM Positron
OFM Dark
Vector
OFM Dark
OFM Fiord
Vector
OFM Fiord
VersaTiles Colorful
Vector
VersaTiles Colorful
VersaTiles Neutrino
Vector
VersaTiles Neutrino
VersaTiles Graybeard
Vector
VersaTiles Graybeard
VersaTiles Eclipse
Vector
VersaTiles Eclipse
VersaTiles Shadow
Vector
VersaTiles Shadow
Hillshade
Overlay
Hillshade
USGS Hydro
Overlay
USGS Hydrography
Transportation
Overlay
Transportation
Hiking
Overlay
Hiking Trails
Cycling
Overlay
Cycling Routes
MTB
Overlay
MTB Trails
OpenSeaMap
Overlay
OpenSeaMap (Nautical)
BLM
Overlay
BLM Public Lands
Ski Pistes
Overlay
OpenSnowMap Pistes
Railways
Overlay
OpenRailwayMap
Power
Overlay
OpenInfraMap Power
Esri Reference
Overlay
Esri Reference Labels

Plus 1,345 more sources from the OSM Editor Layer Index, filterable by country and type — added with one tap from the in-app Browse Imagery Catalog.

04

Deploy across every device

The same build runs on Android and as an installable web application, with no platform-specific feature gaps.

Android

Google Play, APK / AAB
Min Android 7 (API 24)

Web

Any modern browser
PWA installable

Deploy ZYRN TOPO

One purchase. Every platform, every capability, and every future release — with no subscription, no account, and no cloud dependency.

One-time purchase
ZYRN TOPO
Buy once · Own forever · No renewals
  • Android app on Google Play
  • Web PWA — any modern browser
  • All future version updates included
  • No account, no login, no telemetry
  • Works without a signal when configured
Google Play Download Beta APK

Prefer Google Play when available. The beta APK is provided for Android sideload testing and may require enabling installs from your browser.

No-cost
Web Version
No install · No purchase needed
  • Full map interface in your browser
  • 23 base layers + 22 overlays, plus any map as an overlay
  • GPS tracking and map objects
  • PMTiles tile archive support
  • Team Sync via P2P and LAN
  • Identical interface with unrestricted map navigation
  • Installable as a PWA
Start Mapping Free

Works in Chrome, Firefox, Edge, and Safari. No sign-up required.

Built for search-and-rescue, field teams, and operations that cannot rely on connectivity.

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