Privacy notice
Last updated 12 October 2026.
Who we are
Chalkstream Development runs Predictable and is the data controller for the personal data this page describes. Write to hello@chalkstream.dev with any question about this notice or about your data.
Visitors: what we collect
Every page of this site counts page views with Umami, an analytics tool that runs on our own server. Each page view records:
- the page URL and title, and the page you came from;
- your browser, operating system, device type, screen size and language;
- your approximate location: the country, region and city worked out from your IP address;
- a visitor hash: a code derived from your IP address and browser that changes every month.
Umami uses your IP address to make the hash and to look up the location. It does not store the IP address. Umami stores nothing on your device and reads nothing from it.
The Auto, Light and Dark switch keeps your choice in your browser's local storage, under the key predictable-theme. Nothing from it is sent to us.
The web server keeps standard access logs. Each log line holds the IP address, the page requested, the time and the browser.
Why we collect it
We collect this data to see which pages are read and to keep the site secure. Our lawful basis is legitimate interests. The interest is knowing what visitors read, and spotting abuse in the server logs.
How long we keep it
- Access logs: 14 days.
- Analytics records: indefinitely. They identify nobody: the IP address is not stored, and the visitor hash changes every month.
What we do not do
- We set no cookies.
- We do no cross-site tracking.
- Visitors are not identified.
- No third party receives visitor data. The fonts, the scripts, the images and the analytics all come from our own server.
- Nothing is sold.
If your browser sends the Do Not Track signal, the analytics tool skips your visit to this site.
Where the data lives
Except where this page names another provider, we hold all data on this site on one server rented from Hetzner Online GmbH in Helsinki, Finland. Three backup copies exist:
- Hetzner's automatic daily server images, held in Hetzner's own backup storage in the same datacentre. Seven images are kept, and the oldest is deleted first.
- A nightly copy to a Synology storage device in the United Kingdom, with snapshots up to twelve months deep.
- A daily copy, encrypted before it leaves our systems, in Synology C2 cloud storage in Frankfurt, Germany, about one month deep.
Your rights
Under UK data protection law you have these rights:
- Access. You can ask us for copies of your personal information, and for details of where we got it and who we share it with.
- Rectification. You can ask us to correct or delete personal information you think is inaccurate or incomplete.
- Erasure. You can ask us to delete your personal information.
- Restriction of processing. You can ask us to limit how we use your personal information.
- Objection. You can object to our use of your personal information.
- Portability. You can ask us to transfer the personal information you gave us to another organisation, or to you.
Some rights depend on the lawful basis. The right to object applies where we rely on legitimate interests, and the right to portability applies where we rely on contract. We never rely on consent, so there is no consent to withdraw. Some exemptions apply, and the ICO's website explains them.
To make a request, email hello@chalkstream.dev. We respond without undue delay, and in any event within one month.
How to complain
If you have any concern about our use of your personal information, email hello@chalkstream.dev and we will put it right. If you remain unhappy after raising it with us, you can complain to the Information Commissioner's Office (ICO), the UK supervisory authority:
Information Commissioner's Office
Wycliffe House, Water Lane
Wilmslow, Cheshire, SK9 5AF
Helpline: 0303 123 1113
ico.org.uk/make-a-complaint