Starting 2 January 2026 I am moving the site to new system.
The content part (free online tutorials and research) is available normally.
The user account section is paused for a few days until I complete migrating all user data and test everything.
This means you cannot login or order calculators now.
If you need to re-download a calculator you bought in the past, contact me.
Get a Calculator for Free
If you want a calculator and don't want to wait until orders are restarted, you can get it for free if you give me honest and constructive feedback on anything you like or dislike about the site.
Just give me feedback using the online contact form and let me know which calculator you want. I will send it to you by email.
Note: "Looks good" does not qualify (fails the "constructive" condition). Please be specific.
If you find and report a bug, you get two calculators of your choice.
See overview of all available calculators.