Almost nothing, by design. The tools on this site run entirely in your browser. The numbers you type or the files you drop are processed on your machine and never sent to a server. There are no accounts, no signup walls, and we set no cookies.
This site is run by Sebastian Zijlstra, Sofia, Bulgaria, as a personal project rather than a company. That makes me the data controller for the little that is processed here. Reach me at [email protected] or on LinkedIn ↗.
Some tools remember your work between visits. Lockbox, the Ledger, and Test Receipt save what you enter in your browser's local storage, which is a private box on your own device. It is not a cookie, it is never transmitted, and I cannot see it. Clearing your browser data erases it, and there is no backup on my side, so export anything you want to keep.
For traffic counts we use Cloudflare Web Analytics, which is cookieless and doesn't profile visitors. It tells us aggregate things like how many people visited a page and from which country, and nothing about who you are.
In the interest of honesty: the site is hosted on Cloudflare Pages, which like every host keeps routine server logs containing IP addresses for security and reliability, and fonts load from Google Fonts, so your browser makes a request to Google's servers when a page loads and Google sees your IP address in the process. Neither involves anything you type into the tools. Both rest on a legitimate interest in keeping the site running and looking right.
Under the GDPR you can ask for access to your personal data, correction, erasure, or restriction, and you can complain to a supervisory authority. In practice there is almost nothing for me to hand over, because I hold no accounts, no email list, and nothing you enter into the tools. If you write to me, I will hold that message for as long as the conversation is useful and no longer.
If any of this changes, the date at the top of this page changes with it. The terms of use cover the other half of the picture.