What is KML?
KML (Keyhole Markup Language) is an XML-based format for expressing geographic annotation and visualisation. Originally developed by Keyhole, Inc. — later acquired by Google — KML became an Open Geospatial Consortium (OGC) standard in 2008 (OGC KML 2.2). It is the native data format for Google Earth and Google Maps.
KML goes beyond simple geometry storage. It supports rich styling information including icon symbols, line colours, polygon fills, and opacity. It also defines camera viewpoints, ground overlays (image tiles draped over terrain), screen overlays, network links for streaming updates, and time-based animations — making it a full presentation format, not just a data format.
KMZ is simply a ZIP-compressed archive containing a KML file (typically named doc.kml) along with any referenced resources such as custom icons, ground overlay images, or 3D models. Most applications that read KML also accept KMZ transparently.
Key Features of KML
- Rich styling: Inline styles and shared StyleMaps control icon appearance, line width/colour, polygon fill, and label visibility.
- 3D support: Extrude geometries, set altitude modes (clampToGround, relativeToGround, absolute), and embed COLLADA 3D models.
- Time animation: TimeSpan and TimeStamp elements enable temporal playback of features in Google Earth's timeline slider.
- Network Links: Dynamically load and refresh data from remote servers, enabling live tracking and real-time dashboards.
- Ground & Screen Overlays: Drape raster images over terrain or pin informational graphics to the screen viewport.
- Folder hierarchy: Organise features into nested folders with visibility toggles, mirroring a layer-tree structure.
- HTML descriptions: Each Placemark can contain rich HTML in its description balloon, including images, links, and tables.
Convert FROM KML
Export your KML or KMZ data to other widely used geospatial formats.
Convert TO KML
Import data from other formats and create KML files for Google Earth and Google Maps.
Common Use Cases for KML
Google Earth Presentations
Create flyover tours, annotated placemarks, and styled overlays for client presentations, classroom teaching, or public engagement.
Google My Maps
Import KML files directly into Google My Maps to create shareable, collaborative custom maps with markers, lines, and shaded areas.
Real Estate & Site Selection
Overlay property boundaries, zoning layers, and points of interest on satellite imagery for quick visual assessments of potential sites.
Search & Rescue Operations
Share search grids, last-known-position markers, and helicopter landing zones via KML files that field teams open on tablets with Google Earth.
Tourism & Travel Planning
Distribute hiking trails, scenic viewpoints, and accommodation locations as downloadable KML files that visitors can load on their devices.
Time-Series Visualisation
Animate historical changes — urban expansion, glacier retreat, wildfire spread — using KML's TimeSpan elements and Google Earth's timeline slider.
Frequently Asked Questions
What is the difference between KML and KMZ?
KMZ is simply a ZIP archive containing a doc.kml file and any supporting resources (images, icons, 3D models). KMZ files are smaller and easier to share. Most applications that open KML will also open KMZ transparently.
Will converting KML to GeoJSON preserve my styles?
GeoJSON does not have a built-in styling specification. When you convert KML to GeoJSON, geometry and attribute data are preserved, but icon symbols, line colours, and polygon fills are stored as feature properties rather than being rendered automatically. You can re-apply styles in your mapping library.
Can I convert KML files with ground overlays?
Ground overlay images (raster data) are not vector features and cannot be converted to vector formats like GeoJSON or Shapefile. The converter will extract all vector Placemarks (points, lines, polygons) from your KML.
How do I open a KML file?
Google Earth (desktop and web), Google Maps, QGIS, ArcGIS, and many mobile mapping apps can open KML files directly. You can also view the raw XML in any text editor.
Is my KML data uploaded to a server?
No. MapfileConverter processes your file entirely in your browser using WebAssembly. Your KML data never leaves your device, ensuring full privacy and security.
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Upload a KML or KMZ file and convert it to GeoJSON, Shapefile, GPX, or DXF in seconds — free and completely private.
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