GPS Genius: GNSS & GPS Test

GPS Genius shows everything your phone's GNSS receiver actually measures: where you are, how much to trust it, and every satellite and signal behind that answer. Two modes read the same fix — Simple for a plain-language answer, Pro for the full instrument.

Nothing leaves your phone. No account, no ads, no analytics, no tracking.

POSITION AND FIX QUALITY
• Coordinates in five formats — decimal degrees, DMS, DDM, UTM, MGRS — with copy, share and open-in-maps
• Horizontal and vertical accuracy, fix age, time to first fix (TTFF), fix count, best accuracy
• Ellipsoid and MSL altitude, speed, bearing and the provider behind the fix
• PDOP, HDOP and VDOP, satellites and signals used against those in view
• Average and maximum C/N0, and whether the fix is dual-frequency

SKY VIEW
• Live polar plot of everything overhead, device-up or north-up
• GPS, GLONASS, Galileo, BeiDou, QZSS, NavIC and SBAS, each in its own colour
• Ringed markers are the satellites in your fix; size grows with signal strength
• Tap a satellite for its azimuth, elevation, carrier band and C/N0

SIGNAL DETAIL
• One row per signal with its band — L1, L2, L5, E1, E5a, E5b, B1I, B1C, B2a and more
• C/N0 bar chart, strongest first, with filled bars for the signals used in the fix
• Sort and filter by constellation

DIAGNOSTIC TOOLS
• Accuracy test — check reported accuracy against a surveyed position
• Local map — offline north-up plot of your fix and ground truth
• NMEA monitor — the live sentence stream straight from the receiver
• A-GPS assist — inject time and PSDS, or clear aiding data, and watch TTFF change
• Compass — magnetic or true heading with the local declination
• Time and sky — GNSS UTC against system time, daylight, moon phase
• Device capabilities — what your chipset supports, measured not assumed
• GNSS health report — a one-page PDF of a session, to file or send
• Glossary — every term the app uses, in plain English

SESSIONS
• Record a session and save it; there is no limit on how many you keep
• Duration, fix count, best accuracy, satellites used and visible
• Export a session as GPX or CSV, or back up the whole store as one archive

MADE FOR
• Anyone checking whether a phone's GPS is broken before paying for a repair
• Drone pilots running a satellite check before takeoff
• Surveyors and field engineers who need a record of the conditions they worked in
• Hikers, drivers, geocachers and sailors who want to know how good the fix is
• Anyone curious about what those satellites are saying

PRIVACY BY CONSTRUCTION
Location is read only while the app is open in front of you. There is no background location permission and no foreground service, so it cannot read your position when you are not looking at it. Saved sessions live in the app's own private storage, excluded from Android cloud backup and device transfer, so they do not leave the phone even through a Google account backup. The app has no backend and sends no telemetry. It makes two kinds of network request, both only when you ask: Android's own A-GPS assistance from the A-GPS tool, and Google Play Billing if you decide to buy.

ONE PURCHASE, NO SUBSCRIPTION
Every reading is free, in both modes, forever — every number, the sky plot, the signal table, every tool's live display, and unlimited saved sessions. One optional one-time purchase unlocks what you carry away with you: GPX and CSV export, the GNSS health report PDF, NMEA capture to a file, backup archives, and session comparison. No subscription, no renewal, no account, and it keeps working offline once bought.

WHAT YOUR HARDWARE DECIDES
Requires Android 8.0 or later and a device that reports GNSS status. Some measurements — DOP, dual-frequency, raw NMEA — depend on what your chipset and Android version expose. GPS Genius shows what your hardware gives it and says so when a value is unavailable, rather than inventing one.

Privacy policy: https://glippi.dev/projects/gpsgenius/privacy-policy
Support: gpsgenius@glippi.dev