The Open Platform for Spatial Geometry & GIS
Inspect, plot, validate, and convert Well-Known Text (WKT) and GeoJSON geometries instantly. Powered by client-side WebAssembly, Proj4, and Leaflet. 100% private with zero data transmission.
Core Geospatial Utilities
Zero-install browser utilities engineered for fast spatial debugging, coordinate inspection, and layer styling.
WKT Map Viewer & Plotter
Paste or upload Well-Known Text strings (Point, Polygon, MultiPolygon, LineString) to render on interactive satellite and street maps. Inspect coordinates, reproject CRS, and export as GeoJSON.
GeoJSON Visualizer & Inspector
Visualize RFC 7946 GeoJSON Feature and FeatureCollection datasets. Click features to inspect key-value properties, examine coordinate arrays, adjust layer opacity, and export to WKT.
WKT Syntax & Topology Validator
Check your WKT strings for grammatical errors, missing parentheses, inverted coordinates, unclosed rings, and self-intersections before running production database queries.
Authoritative Technical Guides
Deep-dive technical tutorials, specifications, and spatial database cheat sheets authored by geospatial engineers.
The Definitive Guide to Well-Known Text (WKT) Geometry
Exhaustive specification of all 18 WKT types, 2D/3D/4D coordinate dimensions (Z, M, ZM), polygon hole winding order, and PostGIS queries.
GeoJSON Specification Guide (RFC 7946): Structure & Best Practices
Comprehensive reference on Feature and FeatureCollection schemas, the right-hand winding rule, bounding boxes, and precision optimization.
Understanding Coordinate Reference Systems: EPSG:4326 vs EPSG:3857
Learn the mathematical differences between geographic (degrees) and projected (meters) systems, Mercator distortion, and Proj4 reprojection.
PostGIS Spatial SQL Guide & Performance Cheat Sheet
Master ST_GeomFromText, ST_Intersects, ST_DWithin, GiST spatial indexing, bounding box operators (&&), and high-performance spatial joins.
Geospatial Data Formats Guide: Shapefile vs GeoJSON vs KML vs GPX
An architectural comparison of GIS vector formats: attribute limitations, binary encoding, web streaming, file size benchmarks, and conversion tools.
Geospatial Vector Formats Comparison
Understand how popular GIS vector formats compare across encoding, attribute schemas, and performance constraints.
| Format | Encoding | Attributes | Coordinate Order | Web Ready? | Primary Use Case |
|---|---|---|---|---|---|
| WKT | Plain ASCII text | Geometry only | [X, Y] (Lng, Lat) | Yes (Text) | Database queries (PostGIS, MySQL, Snowflake) |
| GeoJSON | JSON (UTF-8) | Arbitrary nested JSON | [Longitude, Latitude] | Native JS | Web mapping (Leaflet, Mapbox, REST APIs) |
| Shapefile | Binary + dBASE IV | 10-char DBF columns | Defined in .prj | Requires parser | Desktop GIS (ArcGIS, QGIS, Government open data) |
| KML / KMZ | XML text / Zipped | HTML balloon markup | [Longitude, Latitude, Alt] | Google Earth | 3D fly-throughs, styling, Google Earth visualization |
| GPX | XML text | GPS telemetry only | Latitude, Longitude attributes | Requires parser | GPS receivers, fitness tracking (Garmin, Strava) |
Common Developer Challenges Solved
Step-by-step solutions for everyday GIS development hurdles.
Visualizing PostGIS Queries
Instead of launching heavy desktop software like QGIS, extract geometries as text using SELECT ST_AsText(geom) and paste them straight into our WKT Viewer for immediate rendering.
Fixing Inverted Coordinates
If your geometries land in the ocean off Africa (Null Island), your coordinates are inverted. Use our WKT Validator or GeoJSON Viewer to detect and flip Lat/Lng to Lng/Lat.
Reprojecting Local Projections
Working with British National Grid (EPSG:27700) or Web Mercator (EPSG:3857)? Enter your source EPSG code to automatically transform geometries into WGS84 for map display.
Frequently Asked Questions
Common questions about Spatial-Sandbox tools, privacy, and geospatial standards.
Is Spatial-Sandbox free to use?
Yes, 100% free and open to developers, researchers, and GIS specialists. No account registration or subscription is required.
Is my spatial geometry data uploaded to any servers?
No. All geometry parsing, reprojection, and rendering take place strictly in your web browser session using client-side JavaScript and Proj4. Your data never leaves your computer.
What is the difference between WKT and GeoJSON?
WKT (Well-Known Text) is a plain-text spatial format standardized by the OGC and returned by databases like PostGIS. GeoJSON (RFC 7946) is a JSON-based spatial standard that pairs geometries with property attributes and is natively supported by web mapping libraries.
Why is my polygon rendering in the ocean off West Africa?
This is the infamous 'Null Island' coordinate inversion bug. GIS standards (WKT and GeoJSON) require Longitude (X) followed by Latitude (Y). If your data was recorded as Latitude, Longitude, swapping them will fix the issue.
How can I reproject coordinates from a local projection?
In our WKT Viewer, enter your source EPSG code (e.g. EPSG:3857 for Web Mercator or EPSG:27700 for British National Grid) into the CRS box. Spatial-Sandbox will fetch the projection parameters and reproject your coordinates on the fly.