Sandpiper — Privacy Policy
Last updated: 9 October 2026
Sandpiper is a tide-times app for Android, published by Jeremy Sayers. This policy explains what the app does with information. It is short because the app does very little with it.
Contact for privacy questions: masterdigerati@gmail.com
The short version
Sandpiper has no account system, no advertising, no analytics and no server of its own. The developer receives no data from the app and cannot see where you are or what you look up.
Tide, moon and spring/neap/king-tide predictions are calculated on your phone from data bundled inside the app, so they work with no signal. The app uses the internet only to draw the map, to search for place names, and to fetch marine weather (buoy readings, forecasts, alerts and map overlays), as described below.
Your location
If you allow it, the app reads your phone's location to find the tide station nearest to you and to centre the map on you. Location access is used only while the app is open, and you can use the app without it by searching or tapping the map.
Your location is not sent to the developer. The last spot you selected is stored on your phone so the app can reopen on it; it is never uploaded. Reading the location is done through Google Play services, which has its own privacy policy.
What leaves your phone
The app makes network requests to the third-party services below. None of them goes to the developer. Positions are rounded before they are sent where the service allows it.
| Request | Sent to | What it contains |
|---|---|---|
| Map tiles | OpenFreeMap (openfreemap.org) | The map area you are viewing, so the right tiles can be returned, and your IP address. |
| Place-name search | Photon, a geocoder operated by komoot (photon.komoot.io) | The text you type in the search box, the map position you are looking at rounded to about 11 km, and your IP address. |
| Marine forecast, coastal waters forecast and weather alerts | The US National Weather Service (api.weather.gov) | The spot you selected rounded to about 1 km, and your IP address. |
| Live buoy readings | NOAA National Data Buoy Center (ndbc.noaa.gov) | Only the identifier of a nearby buoy (the app chooses the buoy on your phone), and your IP address. |
| Map overlays you switch on (radar, nautical charts, satellite clouds, sea temperature) | NOAA (opengeo.ncep.noaa.gov, gis.charttools.noaa.gov) and NASA GIBS (gibs.earthdata.nasa.gov) | The map area you are viewing, so the right tiles can be returned, and your IP address. Nothing is requested unless you turn an overlay on. |
Searching for a tide station by name, the tide and moon calculations, your saved places and the month calendar all happen entirely on your phone and send nothing.
These services are operated by other parties and have their own privacy policies. The app does not send them your account details (there are none), your device identifier, or your precise location.
What is stored on your phone
- The last spot you picked, so the app can reopen on it.
- The places you saved (a name and a position for each).
- Your choice of units (metres or feet) and of map overlay.
These are held in the app's private storage and are deleted when you clear the app's data or uninstall it.
What the app does not do
- It does not create accounts or ask for your name, email or phone number.
- It does not show ads or use an advertising ID.
- It does not include analytics or crash-reporting software.
- It does not sell or share personal information.
Children
Sandpiper is not directed at children and does not knowingly collect any personal information from anyone.
Changes to this policy
If the app's handling of information changes, this page will be updated and the date at the top changed.
Not for navigation
Tide predictions are astronomical and do not include the effects of weather, wind or air pressure. They are for planning only and are not a substitute for official tide tables or navigation charts. Weather alerts shown in the app are informational copies of National Weather Service alerts; the app does not send notifications.
Data sources
Tide predictions use harmonic constants from NOAA (public domain) and from TICON-4 (CC BY 4.0), compiled in the open Slackwater tide database. Marine weather: NOAA National Data Buoy Center and National Weather Service. Radar and nautical charts: NOAA. Satellite clouds and sea temperature: NASA GIBS. Map data © OpenStreetMap contributors, OpenMapTiles, served by OpenFreeMap. The moon image is from NASA's Lunar Reconnaissance Orbiter.