CSV, KML, WKT and Polyline Tools

Not every map dataset arrives as a proper GIS file. Spreadsheets, Keyhole placemarks, WKT strings and Google's encoded polylines all carry geometry in their own way. Check a coordinate table with the CSV coordinate validator and the CSV row counter, measure a path drawn in KML with the KML path length calculator, and decode a route string with the encoded polyline decoder.

The most common failure in this family is silent: a column that looks like latitude but holds longitude, a header row counted as data, a blank coordinate parsed as zero, or a WKT polygon whose rings are not closed. Each tool reports the specific rows or coordinates it rejected instead of quietly dropping them, because a map that is missing features without saying so is worse than an error message. WKT validation covers structure and balance; it is not a geometry engine and will not tell you whether a polygon crosses itself.

For JSON-based geometry, the GeoJSON sub-hub has the equivalent checks, and for recorded tracks the GPX tools cover distance, elevation and speed. To plot a sanitised CSV on a map, use the CSV to map converter.