Polygon output · browser-based
Draw closed smooth curves on a map. Click control points to define a smooth curved area shape, double-click to finish. Export as GeoJSON. Free GIS curve tool.
Closed Curve guide
ClosedCurve creates a smooth closed curve polygon through interpolation of control points. Unlike standard Polygon with straight edges, ClosedCurve generates a mathematically smooth curve passing through all clicked vertices. It produces organic, flowing shapes ideal for natural boundaries, survey areas, and aesthetic map regions.
Polygon
geometry inside a FeatureCollection.
GeoDataViewer Draw is a free browser-based GeoJSON editor for creating points, lines, polygons, arrows, sectors, and smooth curves. It keeps a familiar map-and-JSON workflow while adding specialized shapes that standard GeoJSON editors often do not expose as drawing tools.
GeoDataViewer is not affiliated with geojson.io. Both tools are useful: choose the editor that matches the geometry types and workflow you need.
| Capability | GeoDataViewer Draw | geojson.io |
|---|---|---|
| Drawing modes | 12 standard and extended drawing types. | Core point, line, polygon, rectangle, and circle tools. |
| Live JSON editing | Editable FeatureCollection with immediate map preview. | Editable GeoJSON with a synchronized map. |
| Browser-local processing | Drawing, editing, and export stay on your device. | Browser-based editing for GeoJSON workflows. |
| Import and export | Import JSON or GeoJSON, then copy or download GeoJSON. | Import and export common spatial data. |
| Extended arrows and curves | Straight, diagonal, dove-tail, double-arrow, curve, and sector modes. | Focused on common map-drawing shapes. |
Draw standard Point, LineString, and Polygon features plus directional arrows, sectors, smooth curves, and gathering areas. Every extended symbol is exported as interoperable GeoJSON with its original drawing mode preserved in the feature properties.
Core GeoJSON shapes for locations, routes, boundaries, and fast sketches.
A GeoJSON Point is a single geographic coordinate [longitude, latitude] representing a specific location.
A GeoJSON LineString (commonly called a Polyline) is a sequence of two or more connected coordinate points forming a linear path.
A GeoJSON Polygon represents an enclosed area defined by a closed ring of coordinates where the first and last points are identical.
Freehand drawing allows you to draw lines naturally by holding the mouse button and dragging across the map.
Polygon symbols that add direction, movement, and tactical intent to a map.
StraightArrow draws a straight directional arrow between two points on the map.
DiagonalArrow draws a curved or angled arrow between two points.
DoveTailDiagonalArrow draws an arrow with a split or notched tail (dovetail design).
DoubleArrow creates a bidirectional arrow symbol with arrowheads at both ends.
Smooth lines and specialized areas for coverage, assembly, and natural forms.
ClosedCurve creates a smooth closed curve polygon through interpolation of control points.
PlotSector draws a pie-slice shaped area defined by a center point, a start angle direction, and an end angle direction.
GatheringPlace creates a smooth closed assembly, staging, or rendezvous area from 2-3 control points.
PlotLineString draws a smooth curved line through control points using curve interpolation.
Select any of the 12 geometry and symbol types from the toolbar.
Click, drag, or place control points to create the selected geometry.
Use Select / edit to move map vertices, adjust advanced-shape control points, or refine the FeatureCollection in the live JSON editor.
Copy the result or download a standards-based .geojson file.
Map editing
Select / edit is the first item in the drawing toolbar (on the left on desktop and above the map on smaller screens). Activate it, click an existing feature, and use the visible handles to reshape the geometry without rewriting its coordinates by hand.
Choose the first item in the drawing toolbar (on the left on desktop and above the map on smaller screens), then click an existing feature on the map.
Drag ordinary GeoJSON vertices or the semantic control points shown for an advanced arrow, curve, sector, or area.
Press Enter to finish, Escape to restore the geometry from the start of the edit, or click empty map space to finish.
Press Delete or Backspace to remove the selected feature. Switching to another drawing tool also finishes the edit.
Map handles support Point, LineString, Polygon, MultiPoint, MultiLineString, and MultiPolygon. GeometryCollection remains visible and editable in the JSON panel, but it has no map handles.
Arrows, curves, sectors, and gathering areas retain semantic control points while they remain editable, so you can adjust their intent instead of dragging every vertex of the generated geometry.
Editable GeoJSON preserves advanced-shape controls for reimport. Final GeoJSON contains the finished standard geometry without control metadata; when reimported, it uses ordinary vertex editing.
The drawing canvas, GeoJSON parser, editor, and download flow run locally in your browser. GeoDataViewer does not upload the geographic features you draw or paste into this page.
A smooth closed curve polygon created by interpolating through control points.
ClosedCurve creates smooth curved edges through interpolation, while Polygon uses straight lines between vertices.