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Cron Parser Next Runs

In short

Calculate next cron job runs. POSIX dom/dow semantics, @yearly/@monthly/@weekly macros, timezones, human-readable description. JSON/CSV/ICS export. Free.

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Parse cron expressions and calculate next execution times. POSIX-correct dom/dow semantics, matching how real cron daemons fire. Macros (@hourly), timezones, human-readable description, JSON/CSV/ICS export.

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100% PrivateNo server uploads, ever
InstantRuns in your browser
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How to Use Cron Parser Next Runs

  1. Enter a 5-field cron expression (minute hour dom month dow) or use a macro (@hourly, @daily, @weekly, @monthly, @yearly, @midnight).
  2. Live validation shows ✓ valid (with macro expansion) or specific error (which field, what value).
  3. Pick number of runs (5-100), start time (datetime-local), display timezone (Local / UTC / ISO 8601 / 7 IANA zones), and export format (text / JSON / CSV / iCalendar).
  4. Calculate. Results show numbered list with main-format date + ISO timestamp + interval gap from previous run.
  5. Copy or download. iCalendar (.ics) imports straight into Google Calendar, Apple Calendar, Outlook.

Frequently Asked Questions

Why doesn’t my cron job run at the time I expected?

The top causes, in order: the server’s timezone is not yours (cron uses the system clock, check with date on the server), DST shifted the wall-clock time, the schedule uses day-of-month AND day-of-week (most crons run when either matches, not both), and a missing minute field turning your 5-field expression into nonsense. Paste your expression into this parser and compare the next-run times it shows, in both UTC and your local zone, against what you expected.

What’s the format of a cron expression?

5 space-separated fields: minute (0-59) hour (0-23) day-of-month (1-31) month (1-12 or JAN-DEC) day-of-week (0-6, where 0=Sun, or SUN-SAT). Each field accepts: literal value (5), range (1-5), list (1,3,5), step (*/10), wildcard (*).

Which macros are supported?

@yearly / @annually = 0 0 1 1 *. @monthly = 0 0 1 * *. @weekly = 0 0 * * 0. @daily / @midnight = 0 0 * * *. @hourly = 0 * * * *. Match Vixie cron and most cron flavours.

What about @reboot, L, W, # extensions?

Not supported. @reboot only fires at system boot – meaningless for time-based “next runs”. L (last day), W (nearest weekday), # (nth weekday) are Quartz/cron-utils extensions not in standard Vixie cron. For schedules using these, use a Quartz-aware tool.

How does timezone display work?

Calculation runs in your browser’s local timezone (matching where cron jobs typically run). Display lets you preview the same instants in a different zone. The ISO 8601 column always shows UTC – the unambiguous “what moment” representation.

Why does the schedule sometimes skip Feb 29?

It only happens in leap years. For a cron like 0 0 29 2 * (midnight Feb 29), runs only appear in leap years 2024, 2028, etc. The calculator correctly skips non-leap-year Feb 29 attempts.

What does the iCalendar export look like?

RFC 5545 .ics file with one VEVENT per run. Imports into Google Calendar, Apple Calendar, Outlook, etc. Each event is 0-duration (point in time). UID format cron-{expr}-{index}@alltoolsverse.com.

What does the interval display mean?

The gap from the previous run to the current run, shown next to runs #2+. Useful for verifying your cron’s actual cadence – e.g., 0 9 * * 1-5 gives 24h intervals Mon-Thu but 72h interval Fri→Mon.

Is the calculation accurate over DST transitions?

The calculation uses JavaScript’s Date arithmetic, which respects browser local DST. On the night when clocks spring forward, jobs at the skipped hour (typically 2am-3am) won’t fire – the calculator correctly omits them. On the night clocks fall back, jobs at the repeated hour may appear twice depending on how Date handles it (browser-dependent). For high-precision DST behavior, run your own cron infrastructure with explicit TZ config.

Is anything uploaded?

No. Pure browser-side parsing and date calculation.

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