The small calculations I do often enough to get tired of doing by hand. Subnet maths, a hardened Cisco baseline, and the MAC and wildcard conversions that never quite stick in memory.
Note
All of these run entirely in your browser. There is no form submission, no API call and no analytics on any of it — the page has no way to see what you type, because nothing ever leaves it. That is also why the config generator emits placeholders instead of asking for passwords.
Found one of these wrong? Tell me on the contact page — I would rather fix it than have someone paste a bad mask into production.