Privacy notice

1. Which sites this covers

• String Tension Lab (stringtension.data-and-ai.hu) – guitar and bass string tension calculator.

Everything else on data-and-ai.hu (Hungarian-language pages, newsletter, contact form) is described in the Hungarian notice. If the two ever differ, the Hungarian version applies.

2. Who is responsible

Controller

István Udvari, private individual – operator of the non-commercial hobby project data-and-ai.hu (Hungary)

Contact

info@data-and-ai.hu – for every privacy question and request (English is fine)

Data protection officer

none; not required for processing of this size (GDPR Art. 37)

3. Visitor statistics (Umami)

We measure which pages and features are used, where visitors come from and what they click, with the open-source Umami running on our own server – no other company receives the data.

What data?

the page viewed (without query parameters and without the part after #), page title, referring page, time, browser and operating system type, device type, screen size, language, country; and the use of the calculator: the settings when it has settled on a result (instrument, string set, tuning, scale length, reference pitch, the result – loose / medium / tight – and the recommended set), which control you used first, choosing a recommended or custom set, saving or clearing your personal feel (only that you did it and how, not the value), switching units, theme or language, copying the link, the chart tooltip, clicks on internal links (path only) and external links (domain only), and arriving at a page that does not exist (the requested path, and whether you came from a link). Only predefined values are recorded – never free text.

How are you recognised?

not in the long run: a visitor is marked by a hash computed from the IP address, the browser type and a secret value that changes every month. The IP address itself is not stored – it is only used at the moment of the request to compute that hash and the country; city and region are not saved. Once the month is over the hash cannot be linked again, so no one can be followed for months.

Why?

traffic statistics; deciding which instrument–string–tuning combinations deserve their own pages and which features to improve

Legal basis

legitimate interest – GDPR Art. 6(1)(f). We do not ask for consent because the measurement stores nothing in your browser and reads nothing from it (no cookies). If “Do Not Track” is switched on in your browser, nothing is measured at all.

How long?

raw page views 13 months; the calculator details 90 days; after that only daily totals remain (e.g. “electric guitar, 10–46, E standard: 14 times”), which are not personal data

Who has access?

the controller; our own server (Hetzner, Germany)

4. Cookies and browser storage

We set no cookies, so there is no cookie banner. String Tension Lab keeps a few settings in your browser’s storage (localStorage), and only when you set them: the theme (st-theme: light/dark), the unit (st-units: kg, lb or N), and, if you save it, your personal feel (st-feel: one tension value per instrument type and how you entered it). These stay in your browser, are never sent to the server, and are not read by the measurement – it only records that a button was pressed (section 3). Remove the personal feel with its “Clear” button, the rest by clearing your browser data. As they are stored at your explicit request for the feature to work, no consent is asked.

The calculator writes its state into the address bar (?i=…&set=…) so that the link can be shared. The measurement does not record it (only the predefined values in section 3), and this site keeps no server access log.

5. Backups

The statistics database is part of the nightly backup: kept for 14 days on the server and 90 days in the off-site copy (Hetzner Storage Box, Helsinki, Finland), plus Hetzner’s server backup for 7 days. Data deleted from the statistics disappears from the backups within this time. The off-site copy is transferred over an encrypted connection (SSH) and accessible only with the controller’s key.

6. Who else is involved (processors)

We do not sell data or pass it on for anyone’s own purposes.

Hetzner Online GmbH

server, server backup, off-site backup, DNS – Germany (Nuremberg); off-site backup: Finland (Helsinki). Industriestr. 25, 91710 Gunzenhausen, Germany · www.hetzner.com

All of this stays within the European Union; nothing from these sites is transferred outside the EU.

7. Your rights

You can ask for access to your data (GDPR Art. 15), correction (16), deletion (17), restriction (18), and you can object to processing based on legitimate interest at any time (21). Write to info@data-and-ai.hu; it is free, and we reply within one month (in complex cases this may be extended by two further months, with notice).

Because the statistics are made without IP addresses and cookies, we cannot find which records are yours either, so we cannot hand them out or delete them individually (GDPR Art. 11).

Complaints: please write to us first. You also have the right to lodge a complaint with the Hungarian authority, NAIH (1055 Budapest, Falk Miksa utca 9–11, www.naih.hu), or with the data protection authority of your own EU country, and to go to court.

8. Changes

When a feature starts or the processing changes, this page and the Hungarian notice are updated together, with a new date and version number; earlier versions remain available as PDF on the Hungarian page.