The open-source surveying platform
Start with the GPS in your pocket. Scale to centimeter RTK with any receiver. Capture the world in 3D — and own every byte of your data.
What we're building
A native SwiftUI app for iPhone and iPad plus a browser-based workspace — survey-first, receiver-agnostic, and free where the incumbents charge.
Two-tier accuracy, one workflow
Every feature works with your phone's built-in GPS (3–5 m, zero setup) and gets better with an external RTK receiver (1–3 cm). Accuracy is captured and displayed honestly either way.
Any receiver, no lock-in
Bluetooth NMEA, BLE, or Wi-Fi — if it speaks NMEA, it works. Emlid Reach gets first-class support, but nothing is locked to one vendor's hardware.
Built-in NTRIP client
NTRIP v1 and v2, saved profiles, a directory of free casters (state CORS networks, RTK2go, and more), and obsessive auto-reconnect for Bluetooth and corrections.
No paywalled linework
Points, lines, polygons, code libraries, COGO, site calibration, stakeout with cut/fill, and PNEZD deliverables — free and open source, forever.
Georeferenced 3D assets
Attach a LiDAR scan or Gaussian splat to any survey point. The asset lands on the map at true coordinates, viewable in 3D by anyone with the share link.
Own your data
Local-first on device, real exports in open formats, and a self-hostable web workspace: docker compose up gets you a full backend on your own server.
Honest accuracy, from day one
Survey data is only as good as its metadata. Every observation records its accuracy tier, fix type, RMS, DOP, correction age, and antenna height.
| Tier | Position source | Typical accuracy | Good for |
|---|---|---|---|
| Standard | iPhone / iPad built-in GNSS | 3–5 m | Recon, asset inventory, sketch mapping |
| Enhanced | External sub-meter receiver | 0.3–1 m | GIS data collection, utilities |
| RTK | External RTK receiver + NTRIP corrections | 1–3 cm | Boundary, topo, stakeout, control, drone GCPs |
| RTK + tilt | IMU tilt-compensated receiver | 1–3 cm, tilted pole | Production surveying |
From the field guide
Practical, vendor-neutral writing on RTK GNSS, geodesy, and modern field workflows — the stuff we're learning and building on.
What Is RTK GNSS? Centimeter-Accurate Surveying, Explained
How carrier-phase corrections turn a $700 receiver into a centimeter-grade instrument.
Budget RTK Receivers in 2026: Survey-Grade Accuracy Under $1,000
The cost floor is collapsing. What you get, what you give up, and what to look for.
Free RTK Corrections: State CORS Networks and Public NTRIP Casters
22 US states run free RTK networks. Here's how to find and evaluate them.
NAD83 vs ITRF: Why Your RTK Coordinates Are 1–2 Meters Off
Datums, epochs, and plate motion — the invisible meter that bites every new RTK user.
Gaussian Splatting for Surveyors: Georeferenced 3D Scans on the Map
Photoreal 3D capture is going open. What it means when a splat has real coordinates.
Why Self-Host Your Survey Data
Survey data is legal evidence and client property. It should live where you decide.
Follow the build
Open Survey is being built in the open by Laan Labs, the team behind 3D Scanner App, OpenShape3D, and OpenPlan3D. Repos, TestFlight, and the browser workspace demo are coming — check back here or read the FAQ.