Daylight saving transitions of an IANA time zone in a year: exact UTC instants, offsets before and after, and the clock change.

Convert between integers (1-3999) and Roman numerals, and check whether a Roman numeral is written in canonical form.

Convert a date and time from one IANA time zone to another, flagging times that do not exist or occur twice at DST changes.

Current date and time in an IANA time zone, with UTC offset, abbreviation and whether daylight saving time is in effect.

Hours of difference between two IANA time zones on a given date, with each offset, accounting for daylight saving.

ISO 8601 week number and week year, day of the year, quarter, weekday and leap-year status for a date.

Convert a number between bases 2 to 36 exactly (binary, octal, decimal, hex), with big-integer precision.

List the vehicle makes NHTSA records for a vehicle type (car, truck, motorcycle, bus, trailer), with an optional name filter.

List the VIN manufacturer prefixes (WMIs) registered for a manufacturer name such as Honda, with country and vehicle type.

Write a whole number in English words (cardinal and ordinal) and as a check-writing amount in dollars and cents.

Find the meeting hours where everyone is within working hours across up to 6 time zones on a date, with local times.

Convert fuel economy between US mpg, UK mpg, km per litre and litres per 100 km, with optional trip fuel and cost.

Apparent temperature: heat index from temperature and humidity, wind chill from temperature and wind, with a danger category.

Convert a value between units of length, mass, volume, area, speed, pressure, energy, power, time or temperature, exactly.

Convert cooking measures: cups, tablespoons, teaspoons, ml, ounces and grams, with weight for flour, sugar, butter and more.

Convert data sizes between bytes, KB/MB/GB/TB (decimal) and KiB/MiB/GiB/TiB (binary), and the time to transfer at a speed.

Turn seconds into a readable duration (2 h 5 min) or parse one like '1d 3h 20m' back into seconds, minutes and hours.

List the vehicle models NHTSA records for a make in a given model year, optionally filtered by vehicle type.

List the vehicle types (car, truck, motorcycle, MPV) NHTSA records for a make, separating exact make matches from look-alikes.

Validate a VIN: 17 characters, no I/O/Q, and the position-9 check digit per 49 CFR 565, with the expected digit.