On this page

Tides API

Tide predictions from harmonic constituents, powered by the open source Slackwater engine. Open and free, no authentication required, and described by an OpenAPI specification.

Getting Started

Authentication

The tides API is open and does not require authentication.

Rate Limits

100 requests per minute per IP address
10,000 requests per day per IP address

If you need higher limits for a production application, please contact us.

Error Handling

Errors are returned with appropriate HTTP status codes and a JSON body:

{
  "message": "Invalid parameters",
  "errors": [
    {
      "path": "/latitude",
      "message": "must be between -90 and 90",
      "errorCode": "INVALID_NUMBER"
    }
  ]
}

GEThttps://api.openwaters.io/tides

API information

GEThttps://api.openwaters.io/tides/extremes

Get extremes prediction for a location

Returns high and low tide predictions for the nearest station to the given coordinates

Parameters

Name	Location	Type	Required	Description
latitude	query	number	✓	Latitude
longitude	query	number	✓	Longitude
start	query	string	—	Start date/time (ISO 8601 format, defaults to now)
end	query	string	—	End date/time (ISO 8601 format, defaults to 7 days from start)
datum	query	string	—	Vertical datum (defaults to station's chart datum)
units	query	string	—	Units for water levels (defaults to meters)

GEThttps://api.openwaters.io/tides/timeline

Get timeline prediction for a location

Returns water level predictions at regular intervals for the nearest station

Parameters

Name	Location	Type	Required	Description
latitude	query	number	✓	Latitude
longitude	query	number	✓	Longitude
start	query	string	—	Start date/time (ISO 8601 format, defaults to now)
end	query	string	—	End date/time (ISO 8601 format, defaults to 7 days from start)
datum	query	string	—	Vertical datum (defaults to station's chart datum)
units	query	string	—	Units for water levels (defaults to meters)

GEThttps://api.openwaters.io/tides/stations/{source}/{id}

Get station by ID

Find a station by its ID

Parameters

Name	Location	Type	Required	Description
source	path	string	✓	Station source (e.g., 'noaa', 'ticon')
id	path	string	✓	Station ID within the source (e.g., '8722588', 'some-dash-string')

GEThttps://api.openwaters.io/tides/stations

Find stations

Search stations by name/ID, find stations near the given coordinates, or list all stations when no filters are provided

Parameters

Name	Location	Type	Required	Description
query	query	string	—	Full-text search query (name, ID, or location)
latitude	query	number	—	Latitude for proximity search
longitude	query	number	—	Longitude for proximity search
maxResults	query	integer	—	Maximum number of stations to return
maxDistance	query	number	—	Maximum search radius for proximity search, in kilometers
bbox	query	string	—	Bounding box in GeoJSON order: minLon,minLat,maxLon,maxLat (longitude first). Longitudes must be within -180..180, latitudes within -90..90, and minLat <= maxLat. minLon > maxLon denotes an antimeridian crossing.

GEThttps://api.openwaters.io/tides/stations/{source}/{id}/extremes

Get extremes prediction for a specific station

Parameters

Name	Location	Type	Required	Description
source	path	string	✓	Station source (e.g., 'noaa', 'ticon')
id	path	string	✓	Station ID within the source (e.g., '8722588', 'some-dash-string')
start	query	string	—	Start date/time (ISO 8601 format, defaults to now)
end	query	string	—	End date/time (ISO 8601 format, defaults to 7 days from start)
datum	query	string	—	Vertical datum (defaults to station's chart datum)
units	query	string	—	Units for water levels (defaults to meters)

GEThttps://api.openwaters.io/tides/stations/{source}/{id}/timeline

Get timeline prediction for a specific station

Parameters

Name	Location	Type	Required	Description
source	path	string	✓	Station source (e.g., 'noaa', 'ticon')
id	path	string	✓	Station ID within the source (e.g., '8722588', 'some-dash-string')
start	query	string	—	Start date/time (ISO 8601 format, defaults to now)
end	query	string	—	End date/time (ISO 8601 format, defaults to 7 days from start)
datum	query	string	—	Vertical datum (defaults to station's chart datum)
units	query	string	—	Units for water levels (defaults to meters)

GEThttps://api.openwaters.io/tides/openapi.json

Get OpenAPI specification