GridDown is a Progressive Web App for tactical navigation, team coordination, and situational awareness that works completely offline. GPS-denied navigation, celestial positioning, mesh radio integration, and sensor fusion for when you can't rely on cellular or satellite infrastructure.
From basic navigation to advanced sensor integration, GridDown provides comprehensive tools for operating when infrastructure is unavailable or untrusted.
Ancient methods, modern precision
Determine your position using sun, moon, and stars when GPS is unavailable or compromised. Camera-based sextant for altitude measurements, automatic sight reduction, and position fixing. No satellites required—just clear sky.
Mesh-networked SA
Share positions and status with your team over Meshtastic mesh radio—no cellular required. View team members on the map, send waypoints, and coordinate movements. Full ATAK/WinTAK interoperability via CoT Bridge for mixed-capability teams.
Environmental awareness
Connect external sensors via Bluetooth and Web Serial for enhanced situational awareness. RadiaCode radiation detection with dose rate and spectrum analysis. RF Sentinel integration for aircraft, ship, and drone tracking. SARSAT beacon monitoring for emergency locating.
Multi-source forecasting
Cache NWS and IEM weather data before going offline, or receive real-time weather via RF Sentinel's FIS-B decoder (978 MHz). View radar, forecasts, and alerts without internet. Barometric pressure tracking for local weather prediction.
Critical situation support
Medical reference database, SOS beacon generator, and contingency planning tools. Pre-plan evacuation routes, cache emergency contact information, and generate distress signals. SARSAT beacon detection shows nearby 406 MHz emergency transmitters.
Radio frequency planning
Generate comprehensive communication plans with frequency allocations, call signs, and schedules. RF line-of-sight analysis using terrain data. Repeater database and coverage mapping. SSTV image encoding/decoding for radio image transmission.
Pre-cached cartography
Download and cache map tiles from OpenStreetMap, OpenTopoMap, USGS, and satellite imagery for offline use. Import GPX tracks and KML overlays. Drop pins, create routes, and annotate the map—all stored locally in your browser.
Every feature is designed to work when traditional infrastructure is unavailable, compromised, or simply out of range.
Service worker caches the entire app. Pre-download maps and weather. Zero network dependency once cached.
Inertial navigation, dead reckoning, and celestial positioning when GPS is jammed, spoofed, or unavailable.
All data stays on your device. No telemetry, no cloud sync, no accounts required. Position sharing is opt-in only.
Progressive Web App runs on any device with a browser. iOS, Android, Windows, Mac, Linux—install once, use everywhere.
CoT Bridge enables bidirectional communication with ATAK, WinTAK, and iTAK for mixed-capability team operations.
Native Meshtastic and APRS integration for off-grid team coordination over license-free mesh radio.
Efficient rendering and optional sensor polling. Night mode and battery-conscious design for extended field use.
Full keyboard navigation, screen reader support, and ARIA compliance. Usable by everyone, in any situation.
GridDown is dual-licensed. Free for personal and non-commercial use under GPL-3.0. Commercial license required for business deployment, hardware bundling, and enterprise use.
| Feature |
Community
Free (GPL-3.0, non-commercial)
|
Professional
Contact for pricing
|
|---|---|---|
| Navigation | ||
| GPS Navigation | ✓ | ✓ |
| Offline Maps (OSM, OTM, USGS) | ✓ | ✓ |
| Inertial Navigation / Dead Reckoning | ✓ | ✓ |
| Celestial Navigation | ✓ | ✓ |
| Route Planning & Elevation Profiles | ✓ | ✓ |
| Team Coordination | ||
| Meshtastic Integration | ✓ | ✓ |
| APRS Integration | ✓ | ✓ |
| CoT Bridge (ATAK/WinTAK) | ✓ | ✓ |
| Position Sharing | ✓ | ✓ |
| Sensors & Integrations | ||
| RadiaCode Radiation Detector | ✓ | ✓ |
| RF Sentinel (Basic: ADS-B, AIS) | ✓ | ✓ |
| RF Sentinel Pro (FPV, FIS-B Weather) | — | ✓ |
| SARSAT Beacon Detection | ✓ | ✓ |
| Support & Licensing | ||
| Personal / Educational Use | ✓ | ✓ |
| Non-Profit / HAM Radio Use | ✓ | ✓ |
| Business / Enterprise Deployment | — | ✓ |
| Hardware Bundling / Sales | — | ✓ |
| Government / Military Deployment | — | ✓ |
| Community Support (GitHub) | ✓ | ✓ |
| Priority Support | — | ✓ |
| Commercial License (non-GPL) | — | ✓ |
| White-Label Deployment | — | ✓ |
| Pre-Configured Hardware Bundles | — | ✓ |
From search and rescue teams to prepared individuals, GridDown serves anyone who needs reliable navigation when infrastructure fails.
Coordinate ground teams in remote areas with no cell coverage. Track team positions via Meshtastic, share search grids, and integrate with SARSAT for beacon detection. TAK interoperability for multi-agency operations.
Navigate through smoke and GPS-degraded conditions. Pre-cache maps of your jurisdiction, plan evacuation routes, and coordinate with incident command via CoT. Offline weather critical for fire weather monitoring.
Maintain situational awareness without depending on potentially compromised infrastructure. RF Sentinel integration tracks nearby aircraft and drones. Discrete operation with no cloud telemetry.
Navigate trails, track elevation, and plan routes in areas without cellular coverage. Cache USGS topo maps before your trip. Share your position with family via Meshtastic relay points.
Pre-plan evacuation routes and cache maps of your area before disaster strikes. Medical reference database for first aid. SSTV capability for emergency communications when all else fails.
Log waypoints and tracks in remote locations. RadiaCode integration for radiation surveys. Export data in standard formats. No cloud dependency means no data sovereignty concerns.
GridDown integrates with a growing ecosystem of affordable, off-the-shelf hardware via Bluetooth and Web Serial.
GridDown is a pure client-side Progressive Web App with no server dependencies. All processing happens on your device, ensuring complete operational security and infrastructure independence.
Download GridDown today. Free, open source, and ready for when you need it most. No account required—just cache your maps and go.
Works on any device with a modern browser • No installation required • Cache maps before going offline
Report vulnerabilities: [email protected]
All permissions are optional and requested only when needed.
GridDown integrates data from the following sources under their respective licenses.
© OpenStreetMap contributors (ODbL)
© OpenTopoMap (CC-BY-SA)
USGS National Map (Public Domain)
NASA GIBS (Public Domain)
Weather data by Open-Meteo.com (CC BY 4.0)
Iowa Environmental Mesonet / NOAA
EPA AirNow (Public Domain)
USGS Water Services (Public Domain)
APRS® is a registered trademark of TAPR
Meshtastic (GPL-3.0)
RadiaCode BLE protocol (MIT)
Search by Nominatim/OSM (ODbL)
NOT FOR SAFETY-CRITICAL APPLICATIONS: GridDown is NOT designed or intended for use in any safety-critical application including aviation navigation, maritime navigation, emergency response coordination, or any application where failure could result in death, injury, or property damage. All navigation data is for INFORMATIONAL PURPOSES ONLY. Always carry backup navigation equipment and verify positions using multiple sources.
CELESTIAL NAVIGATION LIMITATIONS: Celestial navigation features are provided for educational and emergency backup purposes only. Accuracy depends on user skill, equipment calibration, atmospheric conditions, and proper technique. Do not rely solely on celestial navigation for critical position determination.
GPS-DENIED NAVIGATION: Inertial navigation and dead reckoning accumulate error over time. These features are intended as temporary supplements when GPS is unavailable, not as primary navigation methods. Accuracy degrades significantly with distance and time.
SENSOR INTEGRATION: RadiaCode radiation readings, RF Sentinel detections, and other sensor data are for informational purposes only. Do not use for safety-critical radiation protection decisions or aircraft/drone avoidance. Professional equipment and training are required for such applications.
RADIO COMMUNICATIONS: APRS® is a registered trademark of the Tucson Amateur Packet Radio Corporation (TAPR). APRS was developed by Bob Bruninga, WB4APR (SK). APRS integration requires appropriate amateur radio licensing. Meshtastic operation must comply with ISM band regulations in your jurisdiction. Users are solely responsible for regulatory compliance.
TAK/COT NON-AFFILIATION: GridDown is NOT affiliated with, endorsed by, or sponsored by the TAK Product Center, the United States Government, the Department of Defense, or any military or government agency. "Cursor on Target" (CoT) is an open XML schema. TAK interoperability features are provided for convenience and do not imply any official relationship or certification.
THIRD-PARTY DATA & SERVICES: GridDown integrates data from third-party sources including OpenStreetMap, USGS, NOAA, NASA, Open-Meteo, and EPA AirNow. This data may be incomplete, inaccurate, or outdated. BlackAtlas Technology is not responsible for third-party data quality. Always verify critical information through official sources.
NO WARRANTY: GridDown is provided "AS IS" without warranty of any kind, express or implied, including but not limited to warranties of merchantability, fitness for a particular purpose, and noninfringement. The developers assume no liability for any use of this software. The user assumes all risk of use. See Terms of Service and Full Disclaimer for complete details.