Convert FlatGeobuf to KML Online — Free GIS Converter

FlatGeobuf is a powerful format for GIS pipelines, but KML is what you need when sharing spatial data with Google Earth users, embedding in Google Maps, or presenting to a non-technical audience — convert your .fgb file to .kml with geodata.plus.

Why convert FlatGeobuf to KML?

FlatGeobuf excels in performance-critical backend workflows, but its binary format is opaque to non-GIS users and not directly openable in Google Earth or Google Maps. KML is the format of choice when the goal is communication and visualization rather than analysis — it opens with a double-click in Google Earth, can be shared as an email attachment or a link, and displays geographic features in an intuitive 3D environment that any stakeholder can explore without GIS software.

Planners, public agencies, and project teams often store working datasets as FlatGeobuf for speed, then export to KML for presentations, public consultations, or progress reports where accessibility matters more than raw performance.

Why use geodata.plus

• Free tier — convert up to 3 files per month at no cost, no credit card required
• Automatic CRS detection — reads the CRS from the FlatGeobuf header and reprojects to WGS 84 automatically
• Optional reprojection — always outputs WGS 84 (EPSG:4326) as required by the KML specification
• Browser-based — no QGIS, GDAL, or Google Earth Pro install needed; works on any modern browser
• Encrypted transfer — all uploads use TLS; files are stored temporarily in Cloudflare R2 and automatically deleted on schedule
• Auto-deleted output — output files are automatically deleted after 2 days (free tier) and 7 days (Pro); no manual cleanup needed

How it works

1. Upload your FlatGeobuf file (.fgb) using the widget above
2. geodata.plus reads the CRS from the FlatGeobuf header and confirms the geometry type
3. Select KML as the output format; geodata.plus reprojects coordinates to WGS 84 automatically
4. Download your .kml file ready to open in Google Earth, Google Maps, or ArcGIS

FlatGeobuf format

FlatGeobuf is a binary, row-oriented vector format using the FlatBuffers serialization library. A Hilbert R-tree spatial index is embedded at the head of the file, allowing fast spatial queries and HTTP range request access. The CRS is stored in the header alongside the feature schema. FlatGeobuf is used in cloud-native GIS pipelines, Mapbox workflows, and high-performance spatial data APIs.

| Property | Value | |---|---| | Extension | .fgb | | Type | Vector, single file (binary) | | Coordinate system | Any CRS (stored in header) | | Geometry types | Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, GeometryCollection | | Common software | GDAL, QGIS, Mapbox, cloud-native GIS, web APIs |

KML format

KML (Keyhole Markup Language) is an XML-based OGC standard originally developed by Keyhole Inc. and adopted by Google. All coordinates are in WGS 84 (longitude, latitude, optional altitude). KML supports placemarks, paths, polygons, ground overlays, and organizational folders. Its styling system — colors, icons, label scales — makes it well suited for visual presentations. It is the native format for Google Earth and importable into Google Maps, ArcGIS, and QGIS.

| Property | Value | |---|---| | Extension | .kml | | Type | Vector, single file (XML) | | Coordinate system | Always WGS 84 (EPSG:4326) | | Geometry types | Point, LineString, LinearRing, Polygon | | Common software | Google Earth, Google Maps, ArcGIS, QGIS |

Frequently asked questions

How are FlatGeobuf attribute columns represented in the KML output?

Each feature's attribute columns are written as <SimpleData> elements inside a KML <ExtendedData> block. Google Earth displays these in the feature's info balloon when you click on it. All column names and values are preserved, though KML renders them as strings regardless of the original data type.

Can I apply different styles to different feature types in the KML output?

geodata.plus applies a default style per geometry type — a marker for points, a line style for linestrings, and a filled polygon style for polygons. For custom styling per attribute value (e.g., color by land-use class), further customization in Google Earth or a post-processing step with a KML editor is recommended.

My FlatGeobuf has millions of features — will Google Earth handle a large KML?

KML is not designed for very large datasets. Google Earth performance degrades significantly with more than a few thousand features in a single KML file. For large FlatGeobuf datasets, consider using geodata.plus to convert a spatial subset, or export to GeoJSON and use a tiled web map instead.