Time, Cron, and Date Math
Cron expressions you can read, epoch conversions across timezones, ISO 8601 strings, and date math you can run anywhere.
Time, on the surface, looks simple. Then you trip over daylight saving, two timezones you forgot existed, a cron expression written by someone who left the company three years ago, and the realization that 2024 was a leap year.
This hub collects our tools for working with time deterministically — across timezones, across formats, across the ambiguities the calendar and Unix epoch bring.
Tasks covered
- Cron Generator — pick your schedule visually, see the next 5 firing times, copy a working cron string
- Epoch to DateTime — paste an epoch (s or ms), see it across 6 timezones
- Date to Epoch — the reverse direction, with timezone awareness
- Timestamp Diff — compute duration between two ISO 8601 timestamps
- Regex Tester — for parsing time formats out of arbitrary input
Glossary
- Cron Expression — the five-field time string, unpacked
- ISO 8601 — the international standard for date and time strings
Article coverage
- Cron Expression Cheat Sheet — common schedule patterns
- UTC vs GMT vs EST — practical offset conversion
Why these tools run client-side
Time-zone math libraries exist in every language, but they’re often subtly wrong around DST transitions, before-1970, and after-2038 (for 32-bit systems). The tools in this hub use the JavaScript Date object’s behavior — well-tested in millions of browsers — and report results consistently across machines. For most one-off calculations, that’s enough.
Cron Generator — Build Cron Expressions Visually
Build a cron expression with live preview of the next 5 firing times. Each field validates independently. Runs in your browser, no upload.
Epoch to DateTime — Unix Timestamp Converter Across Timezones
Convert Unix epoch timestamps to date and time across 6 timezones (UTC, Los Angeles, New York, London, Tokyo, Shanghai). Auto-detects seconds vs milliseconds. 100% local, no upload.
Epoch to Date — Convert Unix Timestamps to Readable Dates
Convert Unix timestamps to human-readable dates in your local timezone or UTC. Seconds, milliseconds, and nanoseconds, all in your browser.
Date to Epoch — Convert Dates to Unix Timestamps
Convert dates and times to Unix timestamps (epoch seconds). Millisecond and nanosecond variants, all in your browser. No uploads, no limits.
Timestamp Diff — Calculate Duration Between Two Dates or Timestamps
Calculate the exact duration between two dates or Unix timestamps. Output in seconds, minutes, hours, days, weeks, months, and years — all in browser.
Cron to Human — Translate Cron Expressions to Plain English
Translate cron expressions to plain English. Shows the next 5 run times in your local timezone. Standard cron and Quartz syntax supported.
Your files never leave your device. Every conversion happens in your browser. No uploads, no servers, no file size limits.