OnWater

API

Check if a latitude/longitude point is on water or land

Overview

OnWater API provides a RESTful interface to determine if a given lat/lon coordinate lies on water or land. Its core endpoint accepts latitude and longitude as query parameters, returning a JSON response with a boolean 'water' flag, the queried coordinates, and accuracy metadata. Ideal for integration into navigation apps (to warn users of water locations), outdoor planning tools (validating land-based camping spots), location-based services (filtering land-only points), and mapping platforms (enhancing geospatial data layers with water/land context).

Example Integration (JavaScript)

script.js JS


fetch('https://onwater.io/')
  .then(res => res.json())
  .then(data => console.log(data))
  .catch(err => console.error(err));

Key Features

RESTful API
JSON response format
Lat/lon input support
High-accuracy spatial data

Frequently Asked Questions

? Is OnWater API free to use?

Yes, OnWater offers a freemium model with a free tier for limited requests, plus paid plans for higher usage volumes.

? Does it require an API Key?

Yes, you need to sign up on the OnWater website to obtain an API key for making requests.

? What is the response format?

The API returns responses in JSON format, including a boolean 'water' field, queried coordinates, and accuracy information.

Top Alternatives

OpenStreetMap Overpass API Search Google

GeoNames Water Body Data API Search Google

Tool Info

Pricing Freemium

Category Geocoding

Platform Public API

Pros

⊕ Simple endpoint structure
⊕ Reliable water/land classification
⊕ Freemium pricing options

Cons

⊖ Requires API key for access
⊖ Rate limits on free tier
⊖ No additional water type details (e.g., ocean vs. lake)