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GML to FlatGeobuf

Convert GML to FlatGeobuf online for free — right in your browser. No upload, no sign-up, batch conversion, coordinate systems and attributes preserved.

Features

Fast Conversion

Efficiently convert from GML to FGB format

Data Security

All processing is done locally in your browser

Standard Format

Output standard FGB format

gml to fgb

Convert gml to fgb online for free — right in your browser. No upload, no sign-up, batch conversion, coordinate systems and attributes preserved.

Drag and drop files or folders, or click to upload

Related Tools

About

GML

GML (Geography Markup Language) is an XML-based geospatial data encoding standard defined by the Open Geospatial Consortium (OGC). GML provides rich geospatial data modeling capabilities, supporting complex geometry types, topology, coordinate reference systems, and spatiotemporal data. GML is widely used in European and government sectors, often for national spatial data infrastructures (SDI).

FlatGeobuf

FlatGeobuf is a geospatial data format based on FlatBuffers, designed for efficient geospatial data storage and transmission. It supports spatial indexing (based on Packed Hilbert Curve R-tree) enabling spatial filtering during reads, loading only data for the area of interest. FlatGeobuf is particularly suited for web applications and streaming processing scenarios requiring fast random access to large datasets.

Conversion trade-offs

GML: limitations to know

  • Complex format, large files, high parsing overhead
  • Limited interoperability between different GML application schemas
  • Limited web application support, not suitable for online maps

FlatGeobuf: what you gain

  • Read performance far exceeds GeoJSON and Shapefile
  • Single file contains spatial index, no additional index files needed

Why convert GML to FlatGeobuf?

Converting GML to FlatGeobuf is one of the most common workflows in GIS. GML data usually comes from desktop GIS software, government open-data portals, or data exchange with partners, while FlatGeobuf is what modern tools, web maps, and platforms expect. This converter bridges the two: it reads your GML files, keeps geometry and attributes intact, and writes clean FlatGeobuf output — entirely in your browser, so your data never leaves your device.

Frequently asked questions

Are my files uploaded to a server?

No. The conversion runs entirely in your browser using WebAssembly — your files never leave your device.

Is the GML to FlatGeobuf converter free?

Yes, completely free with no sign-up and no usage limits.

Are coordinate systems preserved when converting GML to FlatGeobuf?

By default the output keeps the source coordinate system. If your GML file uses a projected CRS (like UTM), you can search any EPSG coordinate system by keyword or code and reproject in one step. Note: output formats that require WGS84 by specification (KML, KMZ, GPX) always reproject to WGS84 automatically.

Can I convert multiple files at once?

Yes — drop several GML files at once and each one produces its own FlatGeobuf output.

FlatGeobuf at a glance

Key Features

  • Built-in spatial index supporting efficient area filtering queries
  • FlatBuffers-based with zero-copy reads for excellent performance
  • Supports streaming reads for very large datasets

Common Use Cases

  • High-performance rendering of large datasets in web maps
  • Geospatial data streaming and incremental updates

How to Use

  1. 1

    Upload your GML file — drag and drop it onto the page, or browse from your device. You can add several files at once for batch conversion.

  2. 2

    The conversion runs automatically in your browser. No upload, no server — your data stays on your device the entire time.

  3. 3

    Download the FlatGeobuf file. Each input produces its own output, ready to use in your GIS, web map, or archive.