Date & Time Tools

Convert Unix timestamps, parse ISO 8601 strings, convert between IANA time zones, calculate date differences and relative offsets, and parse or build cron schedules with next run times — essential for log debugging and scheduling.

Date & Time Tools

  • Unix Timestamp Converter

    Convert between Unix timestamps (seconds or milliseconds) and readable dates. Paste a timestamp or date string, or leave empty for the current time.

  • ISO 8601 Parser

    Paste an ISO 8601 date-time string to validate it and see a full breakdown across UTC, local time, and common time zones.

  • Time Zone Converter

    Convert a date-time from one IANA time zone to another. Paste a timestamp or date string, select source and target zones, and click Run.

  • Date Difference Calculator

    Find the duration between two dates. Enter start and end dates on separate lines or separated by |, then click Run.

  • Relative Time Calculator

    Add or subtract a duration from a base date. Line 1: base date (or leave empty / type now for current time). Line 2: offset like +3 days, -2 weeks, or +1 months.

  • Cron Expression Tool

    Parse an existing cron expression or build one field by field. Validate schedules, see human-readable descriptions, and preview the next run times in UTC.

Date, Time & Scheduling for Developers

Time is harder than it looks

Unix timestamps, ISO 8601 strings, time zones, daylight saving transitions, and cron expressions are a constant source of bugs. Log entries use epoch seconds, APIs return ISO strings with Z offsets, cron schedulers use five-field expressions, and "what time is it in Tokyo?" requires IANA zone data — not simple UTC offsets.

Tools for common time tasks

  • Timestamp converter — translate Unix epoch (seconds or milliseconds) to human-readable dates
  • ISO 8601 parser — decode standard date strings from API responses
  • Time zone converter — convert between IANA zones like America/New_York and Europe/London
  • Date difference — calculate duration between two dates
  • Cron parser — explain cron expressions and show next run times

Debugging log timestamps

When log lines show 1704067200 or 1704067200000, check whether your system uses seconds or milliseconds — a common off-by-1000 mistake. Paste the value into the timestamp converter to see both interpretations and confirm which matches your log source.

Cron gotchas

Cron dialects differ: standard cron uses 5 fields (minute hour day month weekday), while some systems add seconds or use different day-of-week numbering. Always verify which cron flavor your scheduler (Kubernetes, AWS EventBridge, systemd) expects before copying expressions from documentation.

Frequently asked questions

Is a Unix timestamp in seconds or milliseconds?

Unix timestamps are traditionally in seconds since 1970-01-01 UTC. JavaScript Date.now() returns milliseconds. Logs and APIs vary — if the number has 13 digits it is likely milliseconds; 10 digits is likely seconds.

Why does my cron job run at the wrong time?

Check the server time zone, whether the scheduler uses UTC or local time, and whether your expression uses the correct number of fields. Use the cron parser to preview the next five run times.

How do I handle daylight saving time?

Use IANA time zone names (e.g. America/New_York) rather than fixed UTC offsets. Fixed offsets do not account for DST transitions and will be wrong twice a year.