At a glance
- No cookies
- No tracking
- No analytics scripts
- Nothing from other servers
- No user accounts
This website is built so that as little data as possible arises: no cookies, no tracking, no analytics tools in the pages, no fonts, scripts or pictures from other servers, no contact form and no user accounts. The host only compiles visitor statistics from its server log files (see 2.). What is processed nevertheless is described here.
1. Controller
2. Hosting and server log files
The website is hosted by STRATO GmbH Otto-Ostrowski-Straße 7 10249 Berlin. When the pages are called up, your browser transmits technically necessary data to the server, which can be stored there in log files:
- IP address of the requesting device
- Date and time of access
- page or file called up, amount of data transferred, status code
- previously visited page (referrer), browser and operating system
STRATO anonymizes the IP address already when storing it, so that no conclusion about your person is possible. The data are not merged with other data.
From these log data STRATO compiles visitor statistics (such as the number of calls per page and period), which I can view in my customer area. No cookies are set for this and no scripts are embedded in the pages; the statistics rest solely on the log data named above with the IP address anonymized.
3. Storage in the browser
Some convenience functions remember your settings – and in the settings your own PGN files and your progress – only locally in your browser. This information is not transmitted to the server or to third parties:
| Entry | Storage | What for |
|---|---|---|
chesstoteles-design | localStorage | the chosen design (modern dark, modern light or black and white). |
chesstoteles-board-view | localStorage | the chosen board view (board, structure or colours). |
chesstoteles-database | localStorage | the chosen game collection – on every page with the collection picker. |
chesstoteles-time | localStorage | the chosen time control (classical, rapid or blitz) – on every page with these buttons. |
chesstoteles-database-players | localStorage | the names of the players chosen in an opening (the search beside the collection picker) or in your own files (the search of the picker dialog) – for the label of the choice. |
chesstoteles-studio-layout | localStorage | the layout of the courses in the learning studio and the training – tiles or a table. |
chesstoteles-tournaments-layout | localStorage | the layout of the tournaments – tiles or a table. |
chesstoteles-studio-board-width | localStorage | the width of the board on the course pages, when it was changed at the line beside the board. |
chesstoteles-picker-hint | localStorage | how often and when the hint at the collection picker was shown, or that it is no longer needed. |
chesstoteles-tutorial-invite | localStorage | that the note about the guide has been shown. |
chesstoteles-board-sizechesstoteles-lists-collapsedchesstoteles-focus | localStorage | board size, collapsing of the right column and the focus mode on the page “Book”. |
chesstoteles-focus-treechesstoteles-focus-netchesstoteles-focus-diagramschesstoteles-focus-statisticschesstoteles-focus-chess-gameschesstoteles-focus-model-game | localStorage | the focus mode of opening tree, opening net, diagrams, statistics and games. |
chesstoteles-rail-minimal | localStorage | whether the bar on the left of the pages diagrams, statistics, learn, training, games and compare is shown with or without its labels. |
chesstoteles-game-… | localStorage | on the page “Games”, per collection, the number of the game shown last (after the hyphen the name of the collection). |
chesstoteles-games-board-width | localStorage | on the page “Games” the width of the board. |
chesstoteles-compare | localStorage | the two players compared last on the page “Compare”. |
chesstoteles-memory-optionschesstoteles-memory-best-1-moves | localStorage | entries that begin with chesstoteles- and the name of a learning game (two examples here): chosen settings and best scores of the learning games; in the repertoire duel also the player names entered. |
chesstoteles-learning-studio | localStorage | the former store of your progress (only the lines played without a mistake and your notes). On your next visit to the learning studio or the training it is taken over once into the new progress and then removed. |
chesstoteles-progress | IndexedDB | your progress in the courses and the training: per line, how often and when you played it and whether without a mistake; per move of the course, how often you found or missed it and which wrong moves you played; the days you practised; your notes. None of it leaves your browser. |
chesstoteles-progress | localStorage | the same progress, only if your browser offers no IndexedDB. |
chesstoteles-training-single | localStorage | in the training the choice between one and two boards. |
chesstoteles-own-files | localStorage | My files: the list of the PGN files loaded by you – name, size, time of loading and number of games. |
chesstoteles-own-files | IndexedDB | My files: the content of the PGN files loaded by you (up to 20 MB per file) and the overviews computed from them in the browser (list of the games, opening tree), so the pages open them faster. The files are not uploaded; they can be removed one by one in the settings under “My files”. |
chesstoteles-lock | localStorage | Lock (only if you set it up in the settings): the salt and a check of your password – not the password itself. With it your learning progress and own PGN files are encrypted in this browser. |
chesstoteles-lock-keychesstoteles-open-… | sessionStorage | Lock: while it is unlocked in a tab, the key and a readable copy of the list of your PGN files – for this tab only, deleted when you close it or lock it again. |
chesstoteles-variation-state | sessionStorage | expanded branches, position shown and scroll position of the page “Book” when returning. |
chesstoteles-return-treechesstoteles-return-netchesstoteles-return-diagrams | sessionStorage | search term, scroll position and opened details of opening tree, opening net and diagrams when returning. |
chesstoteles-backup-last | localStorage | the day of your last backup of the progress – so the site reminds you of a new one after 30 days. |
chesstoteles-engine-version | localStorage | the version of Stockfish you chose in the settings (small or full) – without the entry the small one computes. |
chesstoteles-pages-1chesstoteles-files-1 | CacheStorage | copies of the pages and files of chesstoteles you have opened (service worker) – so they work without the internet and as an app. They are files of this website only, nothing about you; 150 pages at most, the oldest go. The game collections are not kept. |
chesstoteles-engine-files | CacheStorage | the full version of Stockfish (service worker), if you chose and loaded it – so it is sent only once; to be removed at any time in the settings under “Stockfish”. |
Entries in localStorage and in IndexedDB remain stored until you delete them; entries in sessionStorage are deleted when the tab is closed.
The storage serves solely to provide the function you use (§ 25 (2) no. 2 TDDDG). You can delete these data at any time via the settings of your browser (“delete website data”); the pages then keep working, only without remembered settings.
On some pages you can switch on a chess engine (Stockfish, GPL-3.0) – on phones (screens up to 640 pixels wide) only on the analysis board and only in its small version; on all other pages it is neither offered nor loaded there. It is loaded from our own server and computes only in your browser; no data is transmitted to us or third parties. In the settings (part “Stockfish”) you choose the version: small (the default, 1.8 MB) or full (99 MB, all processor cores but one). The full version is transmitted only when you have chosen it and switch on the engine or load it explicitly in the settings; it is then kept in the storage of your browser (Cache Storage “chesstoteles-engine-files”, see the table), so it is transmitted only once, and can be removed there at any time. Your choice is kept in localStorage (“chesstoteles-engine-version”). So that the full version can use several processor cores, our server sends every page with the security headers “Cross-Origin-Opener-Policy” and “Cross-Origin-Embedder-Policy”; they prevent content of other websites from being embedded in our pages and transmit no data.
4. Contact by email
If you write me an email, I process your information (address, content of the message) only to answer your request (Art. 6 (1) (f) GDPR) and delete it as soon as it is no longer needed for that and no statutory retention obligations exist.
5. External links
Some links lead to other websites, for example to Wikipedia, Figshare, The Week in Chess, PGN Mentor or Buy me a coffee. Only when you click such a link do you leave these pages; the processing there is governed by the privacy notice of the respective provider.
6. Your rights
You have the right of access (Art. 15 GDPR), rectification (Art. 16), erasure (Art. 17), restriction of processing (Art. 18), data portability (Art. 20) and objection to processing based on legitimate interests (Art. 21 GDPR). To do so, contact the address given above.
You can also lodge a complaint with a data protection supervisory authority (Art. 77 GDPR), for example the authority of your place of residence or the State Commissioner for Data Protection and Freedom of Information of North Rhine-Westphalia (LDI NRW), Kavalleriestraße 2–4, 40213 Düsseldorf, poststelle@ldi.nrw.de, www.ldi.nrw.de.
As of: October 2026