Privacy Policy

TideApp — iOS app, Android app, and website.

Last updated 4 September 2026

The mobile apps

The apps have no sign-in and no profile. Nothing you do in TideApp is attached to your name, your email address, or any account, because there is no account to attach it to.

They are not, however, silent. Earlier versions of this policy said the apps made no network requests; that is no longer true, and the sections below say exactly what they now send, when, and for how long it is kept.

Tide predictions

Tide times and heights are computed on your device from harmonic constituent data for NOAA reference stations that ships inside the app. Choosing a station or viewing a forecast sends no request to us or to anyone else.

Location

If you grant location permission, the app uses your coordinates once, on your device, to work out which tide station is nearest to you. That coordinate is never transmitted, logged, or retained. The app requests location only while you are using it — it has no background location access and cannot track your movement.

There is one way a place you care about does leave your device. If you set a tide alert, the alert names a station, and that station's identifier — not a coordinate — is sent to our alerts service so the server knows which tide to watch.

We cannot tell how you chose that station. It may be the one nearest you, if you used location to find it. It may be a harbour on the other side of the country that you searched for by name. What reaches us is a station from a public NOAA list either way, never your coordinates, and never anything that follows you as you move.

If you never set an alert, no station identifier ever leaves your device. Location permission remains entirely optional either way: if you decline, you can still pick any station manually and the app works normally.

Tide alerts

Tide alerts are sent by a server, not scheduled on your phone. A phone cannot reliably wake itself up days ahead for a tide, so the app tells our alerts service what you want to be told about, and the service sends the notification when the time comes.

When you have at least one alert switched on and have granted notification permission, the app sends:

• Your install ID — a random identifier described below, so the service knows which device a later change belongs to
• A push token — the address your device's notifications are delivered to
• Your platform (iOS or Android) and your unit preference (feet or metres), so the notification text reads correctly
• Whether you have a Pro subscription, since the free tier allows one alert
• Your alerts — for each one, the station, whether it is switched on, and the rule you chose: which tide, how far ahead, on which days

This is sent when you change an alert, and checked when you open the app, so a change that failed to send gets another chance. If nothing has changed, nothing is sent.

Delivery goes through Expo's push notification service and then to Apple or Google, each acting as a service provider. Your notification content passes through them in order to reach your device.

Retention and deletion. Your alerts are stored for up to 180 days after the last time the app synced them, and then deleted automatically. If you switch off your last alert, or revoke notification permission, the app tells the service to delete your record immediately. If you simply uninstall the app, no such message can be sent — your record stops being used at once, since there is no device to notify, and expires under the 180-day window.

Diagnostics and crash reporting

The apps report crashes and performance problems to Datadog, which processes this on our behalf as a service provider. This covers crashes and error stack traces, launch and rendering performance, which screens were opened and which controls tapped, and your device model, operating system version, and app version.

We use this only to find and fix faults. It is not used for advertising or profiling, and it is not sold or shared.

The install ID

On first launch the app generates a random identifier — a UUID — and stores it on your device. It is not derived from your device's hardware, your account, or anything about you, and it cannot be linked back to you by us or by anyone else. Deleting the app's data or reinstalling produces a new one.

It is used to tie your alerts to your device, to group diagnostic reports so one crash is not counted as many, and to keep feature-flag decisions consistent between launches. Because it is persistent and does reach our own alerts service, we declare it as an identifier on both app stores rather than treating it as anonymous.

What is stored on your device

The app saves your selected station, a short list of recently viewed stations, your alerts, and your install ID in local storage, so it can reopen where you left off. This stays on your device and is removed when you uninstall the app or clear its data.

The website

The website runs the same application, but a browser is a different environment and we monitor it for performance and errors using Datadog Real User Monitoring. Datadog processes this data on our behalf as a service provider. The website does not send tide alerts and has no alerts service behind it.

What Datadog receives

• Page views, navigation timing, and resource load performance
• JavaScript errors and diagnostic context
• Browser type and version, operating system, screen size, and coarse geographic region derived from your IP address
• Interactions such as clicks and taps, and long-running tasks that make the page feel slow

Session recording

Roughly one in five website sessions is recorded as a session replay — a reconstruction of what the page looked like and how it was navigated. Text you type into inputs is masked before it is recorded, so the content of form fields is not captured.

We use these recordings only to find and fix usability and rendering problems. They are not used for advertising, profiling, or any form of marketing, and they are not sold or shared.

Location on the web

If you allow location access in your browser, it is used the same way as on mobile: to find the nearest station, on your device. It is not sent to us or to Datadog.

What we never do

• No accounts, logins, or profiles — we never learn your name or email address
• No advertising, ad networks, or advertising identifiers
• No selling or sharing of personal information
• No tracking you across other apps or websites, and no data brokers
• No background location, and no transmission of your coordinates

Retention

• Alerts: kept until 180 days after the last sync, or deleted immediately when you turn off your last alert or revoke notification permission.
• Diagnostics and website monitoring: retained by Datadog for a limited period under our configured retention settings, and deleted automatically when it expires.

Children

TideApp is a general-audience tool for reading tide predictions. It is not directed at children, and it collects no information that identifies anyone, of any age.

Your choices

• Alerts: switch off your alerts, or revoke notification permission in your device settings, and your record on the alerts service is deleted.
• Location: deny or revoke the permission at any time in your device or browser settings. The app remains fully usable.
• Stored preferences: clear the app's data, or your browser's site data, to remove your saved stations and reset your install ID.
• Website monitoring: browser content blockers that block Datadog will prevent monitoring and session recording. The site works normally with them enabled.

Changes

If this policy changes materially — in particular if the apps begin sending anything not described above — this page will be updated and the date at the top revised before the change takes effect.

Contact

Questions about this policy, or about data we hold, can be sent to privacy@madelabs.dev.

TideApp is published by Forrest Grant. See also the Terms of Use.