Demo. Check if coordinates fit within Massasoit National Wildlife Refuge territory
No GIS Database needed. Map generating requires Javascript Library & Internet connection (not needed with text-only mode).

Coordinates (Lat Lon in digital format, separated by a single space)
This is only a basic example. The coordinates of Massasoit Wildlife Refuge (main parcel) contour are preloaded as a Javascript file:
var lonlats = "-70.6479 41.8835, -70.6436 41.8831, ... -70.6479 41.8835"
In reality, one should be able to select the area in question from a list or else enter coordinates on one's own (as of today, your entries are not verified).

Another limitation of this demo: though you may check coordinates as many times as you wish, you can create a map only once. Reload the page for a new map.

Note that the order "latitude, then longitude" in the entry box differs from that in Javascript data file. The latter (longitude first) fits with WKT ('Well-Known Text') standard better and simplifies coding. See page source for more detail.