Engineering calculators: CIDR/subnet math, cron schedules with next-run preview, and epoch/timezone conversion. No servers, all in your browser.
Enter an IPv4 address in CIDR notation, e.g. 10.0.0.0/24. IPv6 gets a basic expand + address count.
5 fields: min hour day-of-month month day-of-week. Supports *, */step, a-b ranges and a,b,c lists.
Pick a common schedule to generate an expression.
Convert between Unix epoch (seconds or milliseconds) and ISO / local time. Auto-detects seconds vs ms.