Date, Time & ID
Calculate and convert dates and times, and generate identifiers such as UUID and ULID. Includes Unix time conversion and Japanese era conversion.
16 tools・Ordered by measured page views over the last 90 days.
ULID Generator
Bulk-generate 128-bit, time-sortable unique IDs (26-char Base32) as a UUID alternative. Cryptographic RNG, count and copy support.
UUID Generator (v1 / v4 / v7)
Bulk-generate v4 (random), v7 (time-ordered) and v1 UUIDs, up to 1000 at once. Also decodes a pasted UUID.
Japanese Era (Wareki) Converter
Convert between Reiwa, Heisei, Showa, Taisho, Meiji and the Gregorian calendar. Era-change boundary dates are judged by exact date.
Unix Time Converter
Convert between Unix timestamps and dates: seconds/ms, time zone and ISO 8601.
Date Difference Calculator
Show the difference between two dates and times as a Y/M/D H:M:S breakdown plus totals in each unit.
Cron Expression Parser
Explain a cron expression and compute the next run times. Supports weekdays, steps, ranges, and @daily macros.
Time Zone Converter
Enter a date and time and see it as local time in major cities worldwide, with daylight saving time detected automatically.
ISO 8601 Duration Converter
Convert ISO 8601 duration strings such as PT1H30M or P1DT2H to seconds and H:MM:SS, and build one from days, hours, minutes and seconds.
Cron Expression Builder
Build a crontab cron expression from the schedule you want. Shows a plain-English description and the next five run times. Runs in your browser.
NanoID Generator
Generate NanoIDs from a length and an alphabet, and see the size of the ID space along with how many years of generation it takes before a collision becomes likely.
Business Day Calculator
Add or subtract working days from a date and count business days in a range, with Japanese public holidays built in.
Excel Serial Number Converter
Convert five-digit values like 45000 to dates and back, handling the 1900 leap year bug, the 1904 system and fractional times.
Age Calculator
Get the exact age from a date of birth and reference date. Also shows kazoe age, days lived and days until the next birthday.
ICS File Generator
Build an ICS (iCalendar) file from a title, date, time and location. All-day events, recurrence, reminders and time zone conversion. Runs in your browser.
Snowflake ID Decoder
Recover creation time, worker ID and sequence from Discord and X (Twitter) 64-bit IDs. Reverse lookup by timestamp and custom epochs.
UUID Inspector
Detect UUID version (v1-v8) and variant, and recover creation time from v1, v6 and v7. Flags whether the node looks like a MAC address.