KML, GeoJSON, or CSV?
When you begin moving geographic data between platforms, you inevitably encounter three common file formats: CSV, KML, and GeoJSON.
For developers and GIS specialists, the differences are second nature. But for writers, designers, marketers, and project leaders who just need to get thirty locations onto a screen, the alphabet soup of file extensions can be confusing.
Choosing the wrong format often leads to lost styling, broken attributes, or bloated files that are difficult to edit.
Here is a straightforward guide to how CSV, KML, and GeoJSON work, where each format shines, and how to choose the right one for your map.
Overview: The Three Contenders
Each format was designed with a different era and purpose in mind.
1. CSV: The Spreadsheet Workhorse
Comma-Separated Values is the simplest and most accessible format in computing. It stores tabular data in plain text, with rows separated by line breaks and columns separated by commas.
- Best for: Point data, addresses, simple category lists, and projects managed in Google Sheets or Excel.
- Strength: Anyone on your team can open, inspect, and edit a CSV without specialized software.
- Limitation: CSV cannot natively store geometry shapes like hiking paths or municipal boundary polygons. Coordinates must live in separate text columns.
2. KML: The Legacy Google Earth Standard
Keyhole Markup Language is an XML-based language developed by Keyhole and popularized by Google Earth and Google My Maps. A KMZ file is simply a zipped KML archive that can bundle images along with the XML code.
- Best for: Exporting existing projects out of Google My Maps or Google Earth.
- Strength: It can bundle basic marker styling, folder structures, lines, and pin icons inside a single archive.
- Limitation: KML files are verbose, heavy, and notoriously inconsistent across different map engines. Editing KML by hand is slow and prone to XML syntax errors.
3. GeoJSON: The Modern Open Web Standard
GeoJSON is an open standard format based on JavaScript Object Notation. It was built specifically to represent geographic features and their non-spatial attributes for modern web applications.
- Best for: Complex web projects, custom boundaries, multi-point routes, and data pipelines.
- Strength: Native compatibility with modern web mapping libraries, clean readable structure, and full support for points, lines, multi-polygons, and custom feature properties.
- Limitation: Non-technical users cannot open and edit GeoJSON comfortably in a standard spreadsheet program.
Direct Format Comparison Matrix
| Criteria | CSV | KML and KMZ | GeoJSON |
|---|---|---|---|
| Primary Use Case | Spreadsheets and point lists | Google Earth exports and legacy GIS | Modern web mapping and apps |
| Geometry Support | Points only via coordinates | Points, lines, and 3D terrain overlays | Points, multi-lines, polygons, geometries |
| Human Readability | Very high in any spreadsheet app | Moderate, verbose XML tags | High for developers, structured JSON |
| File Size | Extremely lightweight | Moderate to large due to XML markup | Compact and web-optimized |
| Non-Spatial Data | Full tabular columns supported | Limited custom schema support | Rich arbitrary JSON properties |
| Ease of Editing | Effortless in Excel or Google Sheets | Requires Google Earth or GIS tools | Requires code editor or JSON tools |
How to Choose the Right Format for Your Project
Use this simple decision tree to determine which format fits your workflow:
Scenario A: You are starting with a list of places
Choose CSV. If you are mapping recommendations, shop locations, historical landmarks, or event spaces, keep your master data in a spreadsheet. It is easy to share with colleagues, clean to maintain, and imports smoothly into modern map tools like Tasmap.
Scenario B: You are migrating away from Google My Maps
Choose KML or KMZ. Exporting your existing layers as KML allows you to bring your coordinates, titles, and descriptions into a modern builder without manually re-typing a single address. Once imported, let your modern builder handle clean styling and responsive layouts.
Scenario C: You are drawing intricate boundaries or trail paths
Choose GeoJSON. If your map includes multi-stage cycling routes, administrative zones, or nature reserve perimeters, GeoJSON preserves precise coordinate arrays and metadata without the bulk of legacy XML.
Importing Data into Tasmap
Tasmap is designed to eliminate format headaches.
- Have a CSV from your team spreadsheet? Drag it into the studio and match your columns in seconds.
- Have a KML export from Google My Maps? Drop it onto the map and watch all your pins transfer immediately.
- Have a GeoJSON file from an open data portal? Tasmap parses points, lines, and properties without requiring extra conversion scripts.
You do not need to be a GIS specialist to work with spatial data. Pick the format that matches your daily habits, and let your map tool handle the rendering.