rooot viewer

Convert FlatGeobuf to GML

Free, in-browser conversion from FlatGeobuf (.fgb) to GML. Drop a file below — the converted output downloads automatically. No account, no software install, no upload retention for direct conversions.

Or open the full viewer to preview on a 3D map first.

About FlatGeobuf

FlatGeobuf (.fgb) is a binary container that lets clients fetch features within a bounding box over HTTP range requests, without downloading the whole file. It is increasingly the format of choice for cloud-native GIS dashboards where GeoJSON would be too large.

Typical producers: GDAL/OGR, pyogrio, flatgeobuf-rs, QGIS.
Typical consumers: MapLibre (via plugin), QGIS, Felt, cloud GIS dashboards.

About GML

GML (Geography Markup Language) is an OGC-standard XML format for encoding geographic features. It is the canonical exchange format for European INSPIRE directives, UK Ordnance Survey Open Data, and many national-mapping-agency products. Verbose, but machine-readable and namespaced for semantic precision.

Typical producers: Ordnance Survey, EU INSPIRE portals, GeoServer (WFS), QGIS, GDAL/OGR.
Typical consumers: QGIS, PostGIS (ogr2ogr), GeoServer, FME.

How to convert FlatGeobuf to GML

  1. Drop your FlatGeobuf file (.fgb) on the area above, or click to browse.
  2. The file is parsed server-side — geometries are normalised to a GeoJSON FeatureCollection internally, then written out as GML.
  3. The converted file downloads automatically. No retention; nothing is kept on the server.

Want to inspect the geometry before converting? Use the full 3D viewer instead — it renders the file on a MapLibre globe with toggleable layers, then lets you convert from the same toolbar.

Related conversions

FAQ

Is the FlatGeobuf to GML converter free?

Yes. rooot viewer is free and requires no account. There are no per-conversion charges.

Do I need to install software?

No. The conversion runs server-side, the result is delivered as a download. Works in any modern browser.

Are my files kept after conversion?

Direct conversions through this page (the form above) do not persist files at all — the bytes are parsed in memory and the result returned. Persistence only happens when you use the main viewer's Open in roooute button, and persisted files are deleted within 24 hours.

What is the maximum FlatGeobuf file size?

50 MB per file.

Does the converter preserve attribute properties?

Yes — feature properties round-trip through the canonical GeoJSON intermediate. Schema differences between source and target formats may force lossy coercions (e.g. shapefile DBF column-name length limits), but rooot viewer applies sensible defaults.