Mergin Maps – QGIS projects in the field

Mergin Maps is developed by Lutra Consulting Limited (England). The following licences apply:

• mobile app: GPL v2
• QGIS plugin: GPL v3
• Mergin Maps Cloud service: proprietary licence held by Lutra Consulting
• self-hosted Enterprise Edition: Mergin Maps Commercial Licence
• self-hosted Community Edition: dual-licensed under AGPL-3.0 and the Mergin Maps Commercial Licence

Licensing is per contributor with write permission; users with a read-only role do not count. Purchase, terms and enquiries are handled directly by Mergin Maps; SEMPERDEAL lists the software for information only and does not sell it.

GeoPackage is suitable for survey layers because it enables fully offline work, automatic merging of changes made by several people and versioning. Shapefiles and delimited text files can be used but not edited collaboratively; PostGIS and WFS require an internet connection.

As background data the app supports, among others, GeoTIFF, JPEG, PNG, COG, MBTiles and Geospatial PDF; ECW and MrSID are not supported because of their proprietary licence. Most formats that QGIS can load can also be used in the app.

The project is prepared in QGIS: background and survey layers, forms, styling and map themes. The Mergin Maps plugin for QGIS uploads the project file (*.qgz) together with its data to the cloud service, from where team members download the project to the mobile app or to another computer running QGIS.

Everyone works on their own local copy. Synchronisation works in both directions; changes to GeoPackage layers are merged automatically by the service, while photos, raster data and shapefiles are copied as whole files.

Yes. The project is downloaded to the mobile device while a connection is available; data and photos can then be collected offline in the field, and the changes are uploaded later, for example via Wi-Fi in the office.

The following do not work without a connection: synchronising, downloading projects, online background maps (WMS/WMTS, WFS, XYZ tiles) and online PostGIS layers. Background maps are prepared for offline use as vector or raster tiles; the DB Sync tool is suitable for PostGIS data.

The Mergin Maps mobile app runs on Android 9 or later and on iPhone and iPad with iOS 16 or later. For Windows 10 and Windows 11, the manufacturer provides an installer (.exe) on its MerginMaps/mobile source code page.

The app can be used without an account. Synchronising via the cloud service, however, requires signing in to Mergin Maps, an internet connection and write permission for the project. Projects and sharing are managed in the browser via the Mergin Maps dashboard.

Three direct connection methods are suitable:

• Bluetooth (Android only)
• network connection via TCP or UDP (Android and iOS)
• for Trimble receivers, the Trimble Mobile Manager app (Android and iOS)

Only if none of these is possible should the operating system's mock location be used; in that case not all receiver data is passed on. The receiver must send data in NMEA format; NTRIP correction data for centimetre-level accuracy is often provided by the receiver manufacturers' apps. The antenna height is entered in the GPS settings of the app, and the Mergin Maps documentation includes a list of devices known to work well.