Free Date Tools — Age, Business Days & Timestamps

Date tools

Date Calculator — Age in years/months/days and days between two dates.
Time Zone Converter — Convert a date and time between IANA time zones — no API, runs locally.
Unix Timestamp Converter — Convert Unix seconds or milliseconds to ISO dates and back — live sync.
Countdown Calculator — Days, hours, and minutes until a target date — or time since a past date.
Add Days Calculator — Add or subtract days from a date — deadlines, expirations, and planning.
Business Days Calculator — Count weekdays between dates or add business days (Mon–Fri).