Why do timestamps sometimes have 10 digits and sometimes 13?
Ten digits usually means seconds. Thirteen digits usually means milliseconds.
Time & Date Tools
Time bugs are easy to create and hard to diagnose. A timestamp may be seconds or milliseconds, an ISO date may be UTC or local, and a cron expression may run in a timezone you did not expect. Small misunderstandings can lead to expired tokens, missed jobs, duplicated events, or confusing logs.
The Time and Date category groups tools for the most common checks: convert Unix timestamps into readable dates, parse ISO date strings into UTC/local/timestamp values, and explain basic five-field cron expressions. The goal is to make hidden assumptions visible before they become production issues.
These tools are especially useful when debugging API payloads, JWT claims, scheduled jobs, analytics events, background tasks, and logs. They do not replace platform-specific scheduler documentation, but they give you a fast way to inspect values and catch obvious mistakes.
Tools
Existing URLs remain active, and new tools are organized under clean category paths.
Convert Unix timestamps to readable dates and convert dates back to Unix time.
Open toolParse ISO 8601 dates and convert them to local time, UTC, Unix seconds, and Unix milliseconds.
Open toolValidate and explain basic five-field cron expressions in plain language.
Open toolRead exp and iat values from JWT payloads.
Convert API timestamps between UTC and local time.
Check basic cron expressions before saving jobs.
Prepare date and timestamp examples for tests.
8 min read
Unix timestamps count time from the Unix epoch, but seconds, milliseconds, and timezones often cause confusion.
8 min read
Cron expressions compactly describe recurring schedules, but fields, timezones, and platform differences matter.
8 min read
JWTs are common in authentication. Learn what the three sections mean and why decoding is not verification.
9 min read
ISO 8601 is a standardized date and time format that helps APIs represent timestamps across systems and timezones.
9 min read
UTC is a shared reference time; local time is what a user sees in a specific timezone and calendar context.
9 min read
Timezone handling is about preserving the difference between an instant, a local date, and a recurring wall-clock time.
9 min read
API timestamps may appear as ISO strings, Unix seconds, Unix milliseconds, or service-specific numeric values.
Ten digits usually means seconds. Thirteen digits usually means milliseconds.
Local output uses the timezone of your browser environment.
No. It explains basic five-field cron expressions. Platforms may add special syntax.
No backend is required for these conversions.