Overview
OnWater is a simple free API that tells you whether a given latitude and longitude coordinate is on water or on land. You pass coordinates and get back a boolean answer — perfect for validating location data or building map-based games. No API key is needed, making it extremely easy to use right away.
Beginner Tip
This API answers one simple question: is this point on water? Use it to validate that users are not accidentally placing markers in the ocean. Latitude ranges from -90 to 90 and longitude from -180 to 180.
Available Data
The kind of data this API exposes, based on its documentation. We could not call the endpoint to confirm the exact field names.
Example Response
Illustrative shape only — we were not able to call this endpoint (it requires credentials or exposes no public sample URL), so the fields below show the kind of data this API returns rather than a recorded response.
{
"status": "success",
"data": {
"result": "Data from OnWater",
"description": "Determine if a lat/lon is on water or land",
"timestamp": "2025-01-15T10:00:00Z"
}
} Field Reference
lat The latitude value you submitted in the request lon The longitude value you submitted in the request water True if the coordinate is on water; false if it is on land Implementation Example
Calls a real endpoint of this API. Replace any placeholder credentials with your own key.
const url = "https://onwater.io/";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data); What Can You Build?
Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.
Common Errors & Troubleshooting
Generated guidance based on this API's documentation, not observed by us. Treat it as a starting point and check against the provider's own error reference.
Metadata Score Breakdown
Estimated from metadata — endpoint not independently tested
Metadata estimate · endpoint not independently tested
Technical Specifications
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