Algalert — last updated 28 September 2026
Who is responsible for your data
ContractGrip, represented by Sam van de Crommert
Registered in the Netherlands, Chamber of Commerce (KvK) number 42033182
info@algalertalgarve.eu
Our registered address is held at the Dutch Chamber of Commerce and is available on request. Email is the fastest way to reach us and we answer every privacy request.
Algalert has no accounts, no names, no email addresses and no photos. A report is one of three buttons. Your location is never stored. The only things kept about you are how far you were from the beach when you reported, and a random identifier your own browser generates. There is no advertising, no profiling and no tracking across other websites.
Your location, and what happens to it. If you allow it, your phone uses your location in two ways.
First, to show the beaches nearest to you, to centre the map, and to notice when you are standing on a beach so the app can ask how it looks. This happens entirely on your phone. Your position is not sent to us for this.
Second, when you submit a report, your position is sent once so the server can check you are actually at that beach. The server works out the distance to the beach and then discards your position. Only the distance is stored — for example, "180 metres from Praia da Luz". Your coordinates are never written to our database, so there is no location history for anyone to read, leak or request.
There is no background tracking. Nothing is used to infer your interests, and nothing is used for advertising.
Which beaches are looked at. When you open a beach, we count one view for that beach for that day, so we can show how much each beach is checked. To count each phone only once a day, your device identifier is combined with a secret and hashed; that hashed value is deleted the following day. What remains is a plain count per beach per day, which says nothing about who looked. If you arrived by scanning a poster at the beach, the count notes that it came from a poster.
A random device identifier. A random value generated and kept in your own browser. It stops one person reporting the same beach over and over, and it lets us weigh how often a device agrees with everyone else so false reports carry less weight. It is not linked to a name, email or account, because there are none. Clearing your browser data erases it and there is no way to link the old one to the new one.
A one-way hash of your IP address, when you report. Your IP address is combined with a secret and hashed before storage, so the address itself is never saved and cannot be recovered from what we hold. It exists only to stop one machine submitting reports for many beaches at once. It is deleted together with the report.
Server logs. Our hosting providers keep standard request logs, including IP address and time, for security and abuse prevention.
| Purpose | Basis |
|---|---|
| Showing the seaweed status of each beach | Legitimate interest: this is the service |
| Checking you are at the beach you report (distance only, position discarded) | Legitimate interest: preventing false reports |
| Showing beaches near you (on your device only) | Your permission, which you can withdraw at any time in your browser settings |
| Limiting how often one device or connection can report | Legitimate interest: preventing abuse |
| Scoring how often a device agrees with other reporters | Legitimate interest: keeping the data honest |
| Improving the forecast from past reports | Legitimate interest: making the service more accurate |
Your browser asks your permission before sharing your location, and you can refuse. Algalert still works without it; your report simply carries less weight because we cannot confirm you were there.
Nothing is sold, and nothing is shared for advertising.
| Data | Kept for |
|---|---|
| Reports: beach, level, distance to the beach, time | 24 months |
| Hashed IP address | Deleted with the report |
| Hashed device value used to count a view once | Until the next day |
| Number of views per beach per day (counts only, not personal data) | Kept |
| Weather and sea observations (not personal data) | 60 days |
| Server logs | As set by our hosting providers |
A report affects what the app shows for up to fourteen days, counting for less as it ages, and a newer report always replaces it. The app always shows how old a report is. After fourteen days it no longer affects anything you see. It is kept beyond that only to measure and improve how accurate the forecast is.
You can ask for access to your data, correction, or deletion, and you can object to processing. Because there are no accounts, we identify your data by the random device identifier — include it with your request, or tell us roughly when and which beach you reported.
Write to info@algalertalgarve.eu. If you are not satisfied with the response you can complain to a supervisory authority: the Autoriteit Persoonsgegevens in the Netherlands, or the CNPD in Portugal.
Algalert is not aimed at children and collects nothing that identifies anyone.
If this notice changes in a way that matters, we will say so in the app before the change takes effect.
Algalert shows an indication based on reports from the public, mentions in local news, and an estimate from wind, swell and the shape of each beach. It is not a measurement, it says nothing about water quality or bathing safety, and conditions can change within hours. Always look for yourself before you get in.