Blackline

Map, measure, and prove any boundary — offline, in the field.

Download for Android  ·  40 MB
v0.1.8 · Android 7.0+ · free · works on essentially all phones (arm64)
Older / 32-bit phone? Use the universal build (113 MB).

What it does

Blackline is a field map that works with no signal. Load a georeferenced block map, see your live GPS dot on it, and walk a boundary — the area in hectares ticks up as you go. Every boundary and measurement is signed on your device and independently timestamped, so it's tamper-evident: you can prove exactly what was measured, where, and when. Import the forester's KML or shapefile; export a signed proof anyone can verify.

How to install

  1. Tap Download for Android above (on the phone you'll use it on).
  2. Open the downloaded Blackline-v0.1.8-arm64.apk.
  3. Allow install from this source for your browser, then tap Install.
  4. Open Blackline and grant Location when asked. GPS works offline.

What it proves — and what it doesn't

✓ This exact boundary/measurement existed at a time and place, signed by this device, independently timestamped.

✗ Consumer GPS is a few metres — honest accuracy is always shown; it is not survey-grade.

Verify the download

SHA-256 · arm64 (40 MB) — file must be exactly 40,381,509 bytes

155f1a73a76a55d1a5e7ab9235c8f02eafadba883bed43a91a122c8ed880bcc9

SHA-256 · universal (113 MB)

a189c1ad50041698ec83c0ed444dcfa90f469fd29b992413254072b4efb476c3