IConverter

interface IUtcOnlyConverter<TDate> {
  convertToUtc(time: string | number | TDate): TDate;
}

interface ILocalOnlyConverter<TDate> {
  convertToLocal(time: string | number | TDate): TDate;
}

interface IConverter<TDate> extends IUtcOnlyConverter<TDate>, ILocalOnlyConverter<TDate> {}

IConverter and IUtcOnlyConverter are both exported from @time-provider/core — which one your timeProvider.converter is follows the plugin, exactly as for IClock. ILocalOnlyConverter is not exported; it appears here because it is part of the public API surface — the local half of what timeProvider.converter offers on a timezone-aware plugin, and a name tooltips will show you — not because you can import it.

Both methods accept an ISO 8601 time string, an epoch-milliseconds number, or an already-converted TDate — other string formats (e.g. RFC 2822, or a date library's own non-ISO toString() output) aren't supported and may throw or produce an unspecified result depending on the underlying date library.

convertToUtc(time) — converts time into a TDate expressed in UTC. Always available.
convertToLocal(time) — converts time into a TDate expressed in the clock's configured local timezone. Only on timezone-aware plugins (IConverter, not IUtcOnlyConverter) — see Timezones & Local Time.

timeProvider.converter.convertToUtc("2026-06-01T12:00:00Z");
timeProvider.converter.convertToUtc(1780488000000);
timeProvider.converter.convertToLocal("2026-06-01T12:00:00Z"); // rendered in clock.timezone

IConverter ​

IConverter