Professional-grade offline GPS navigation for serious trekkers in Vietnam. Route deviation alerts, GPX tracklog management, and SOS emergency broadcast — fully functional with zero internet connectivity.
BUILT FOR THE TRAIL.
NOT THE CITY.
Every feature is designed around the constraint that matters most: you may have no internet. Reliability is non-negotiable.
FULL NAVIGATION — NO SIGNAL REQUIRED
Pre-load OSM-based offline maps before your trek. Navigate, track your position, and follow routes in deep jungle, remote peaks, or areas with zero connectivity.
REAL-TIME OFF-ROUTE DETECTION
TRAILMARK continuously compares your GPS position against the planned route. When you stray, an immediate alert fires — before a minor detour becomes a serious problem.
IMPORT, STORE + SWITCH GPX FILES
Import GPX and KML tracklogs from any source. Organize multiple routes for the same region, switch tracks mid-trek, and export your completed logs.
EMERGENCY ALERT TO NEARBY USERS
When an accident occurs, a single tap broadcasts your location to all nearby TRAILMARK users in real time. Your last known GPS coordinates are transmitted immediately.
POPULAR ROUTES + NEARBY TREKKERS
When connected, discover the most-trekked routes at your destination, see active nearby users on the map, and access community-contributed tracklogs.
MOBILE + WEB
iOS, Android, and browser — all on the same account. Plan routes on desktop, then carry them offline into the field on your phone.
HOW TRAILMARK
WORKS IN THE FIELD.
THREE STEPS.
NO ACCOUNT REQUIRED TO TRACK.
LOAD YOUR ROUTE
Import a GPX or KML tracklog from any source — community routes, personal tracks, or downloaded from popular trekking databases. Your route loads into offline map storage before you leave.
SUPPORTS: .gpx, .kmlTREK OFFLINE
Set out. TRAILMARK tracks your GPS position continuously, rendering your live location against the offline OSM base map. No signal, no problem. Battery-efficient background tracking runs the full day.
BATTERY: OPTIMISEDSTAY ON COURSE
If you deviate more than a configurable threshold from the planned route, TRAILMARK fires an immediate alert. You see your exact position, the distance off-route, and the nearest return point.
THRESHOLD: CONFIGURABLEVIETNAM'S TRAIL
INDEX.
When connected, TRAILMARK surfaces the most-used community tracklogs at your destination. Built by trekkers, for trekkers — starting with Vietnam's most-trekked peaks and routes.
SOS BROADCAST
WHEN IT MATTERS.
One tap sends an emergency broadcast — your exact GPS coordinates, altitude, and timestamp — to every TRAILMARK user within range. First responders and fellow trekkers see your location in real time. Safety over everything. This feature is never gated, degraded, or paywalled.
TREK SAFER.
NAVIGATE BETTER.
Free to download. No subscription required for offline navigation. Available on iOS, Android, and web — built for Vietnam's trails, starting with Fansipan.