Why is there no basemap (roads, place names, imagery) behind the shapes?

A real basemap means fetching map tile images from a third-party server on every pan or zoom, a real, visible network request. This site's entire premise is that nothing you paste or upload ever leaves your browser, so this viewer draws only your GeoJSON's own geometry, fit to its own bounding box, on a plain background with a light graticule border. That's a deliberate, honest design choice, not a missing feature.

What GeoJSON shapes does this render?

Point, LineString, Polygon, MultiPoint, MultiLineString, and MultiPolygon, whether they arrive inside a FeatureCollection, as a bare Feature, or as a raw geometry object (all three get wrapped into a FeatureCollection automatically before rendering). Anything else is skipped gracefully rather than breaking the preview.

How is the geometry positioned in the preview, is it a real map projection?

No, it's a simple linear fit: your data's overall longitude/latitude bounding box is stretched to fill the SVG viewBox, with latitude flipped since SVG's y-axis grows downward while latitude grows upward. That's accurate for seeing shapes relative to each other, but it's not a true map projection like a real basemap would use.

Can I paste just a single geometry, not a full FeatureCollection?

Yes. A bare Feature or even a raw geometry object (like a standalone Polygon) is automatically wrapped into a one-feature FeatureCollection before rendering, so you don't need to construct the full GeoJSON envelope yourself.

GeoJSON Viewer - Preview GeoJSON Geometry as SVG

Overview

Introduction

Sometimes you don't want to convert, validate, or query GeoJSON, you just want to look at it, and actually see the shapes it describes, without pasting it into a full mapping application.

GeoJSON Viewer is exactly that: paste GeoJSON, get an instant SVG preview of its points, lines, and polygons, plus a quick legend of what's in there.

What Is GeoJSON Viewer?

A read-only GeoJSON geometry previewer built on this category's shared SVG-rendering helper, which fits your data's longitude/latitude bounding box to a fixed viewBox and draws lines and polygons as SVG paths, points as small circles.

It's the central 'look at your geo data' tool in this category, every other geo tool that converts to or from GeoJSON links back here, the same way CSV Viewer anchors the CSV tools.

How GeoJSON Viewer Works

The pasted text is JSON.parse'd and normalized to a FeatureCollection: a FeatureCollection passes through as-is, a bare Feature or raw geometry object gets wrapped in one automatically.

That FeatureCollection is handed to the shared geoJsonToSvgPaths helper, which walks every coordinate to find the overall bounding box, then linearly projects each geometry into SVG path/point coordinates ready to render directly.

When To Use GeoJSON Viewer

Use this whenever you have GeoJSON, from an API response, a converted KML/GPX/shapefile, or hand-written test data, and want to quickly confirm it looks like what you expect.

It's especially useful right after using any of this category's converters, as the last sanity check before trusting the converted output.

Often used alongside KML to GeoJSON Converter, GPX to GeoJSON Converter and Shapefile Viewer.

Features

Advantages

Runs entirely client-side, your GeoJSON never leaves your browser and no map tiles are fetched.
Accepts FeatureCollections, bare Features, and raw geometry objects without requiring manual wrapping.
A feature-count and geometry-type legend gives an at-a-glance summary alongside the visual preview.

Limitations

No panning, zooming, or interactivity, it's a static preview fit to the data's bounding box.
No basemap imagery (roads, place names, terrain), by deliberate design, see the FAQ above.
GeometryCollection members and any unrecognized geometry types are skipped rather than rendered.

Examples

A FeatureCollection with two points and a line

Input

{"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"Point","coordinates":[-122.4,37.8]}},{"type":"Feature","geometry":{"type":"LineString","coordinates":[[-122.5,37.7],[-122.3,37.9]]}}]}

Output

An SVG preview with one small circle and one line stroke, both fit to their shared bounding box, plus a legend reading "2 features, Point, LineString"

Each feature's geometry type determines whether it's drawn as a circle (Point) or a path (LineString), and both share the same bounding-box projection so their relative positions stay correct.

Best Practices & Notes

Best Practices

Use this right after any conversion (KML, GPX, or shapefile to GeoJSON) as a quick visual sanity check before trusting the output.
Check the legend's geometry-type list if the preview looks emptier than expected, an unsupported geometry type may be present in your data.
Paste a bare geometry object directly when you just want to check one shape, no need to wrap it in a Feature or FeatureCollection yourself.

Developer Notes

`parseGeoJsonForViewer` in `geojson-viewer.ts` normalizes three possible top-level GeoJSON shapes (FeatureCollection, Feature, or a raw Geometry) into a single FeatureCollection before the component ever calls the shared `geoJsonToSvgPaths` from `geo-svg-render.ts`, keeping the projection math itself completely shape-agnostic and shared with `shapefile-viewer.ts`.

GeoJSON Viewer Use Cases

Sanity-checking GeoJSON right after converting it from KML, GPX, or a shapefile
Quickly previewing an API response's geometry without pasting it into a full mapping application
Visually inspecting hand-written or generated GeoJSON test data before using it elsewhere

Common Mistakes

Expecting to see roads, place names, or imagery behind the shapes, this viewer deliberately draws only your GeoJSON's own geometry, never fetched basemap tiles.
Pasting invalid JSON (a trailing comma, unquoted keys) and expecting the geometry to render anyway, valid JSON is required before geometry parsing even starts.

Tips

If the preview looks stretched, remember the bounding-box fit maps your data's actual lon/lat extent to the viewBox regardless of aspect ratio, that's expected for a simple fit, not a bug.
Pair with Lat/Lng Point Finder if you need to manually add a reference coordinate alongside geometry you're previewing here.

GeoJSON Viewer