What is the difference between Datetime.now() and System.now() in Apex?

Nothing you can measure: both return the current instant, and in our run they were less than one second apart. Pick one and use it consistently.

Why does Datetime.now() show GMT in the debug log?

Datetime stores an instant and its string form is GMT. Call format() to show it in the user's time zone and locale, or format(pattern, timeZoneId) for a named zone.

What is the Time class in Apex used for?

Time holds only hour, minute, second and millisecond, for things like business hours. Build one with Time.newInstance(17, 30, 0, 0) or take it from a Datetime with time(). Methods are in the Apex Reference: Time Class .

How do I format a Datetime as ISO 8601 in Apex?

Use formatGmt('yyyy-MM-dd\'T\'HH:mm:ss\'Z\''), which returned 2026-10-26T07:32:59Z. Patterns follow Java SimpleDateFormat, as the Apex Reference: Datetime Class explains.

How do I get the current time in the logged-in user's time zone?

Datetime.now().format() already converts to the context user's time zone; hour() and date() do too. Use the Gmt versions only when you need GMT.

Datetime Class in Apex: now(), Methods and DST Gotchas

Schedule a reminder for 12:00 PM on Saturday, October 31, 2026, move it one day with addDays(1), and a New York user gets it at 11:00 AM on Sunday. US clocks fell back that night, and addDays adds 24 elapsed hours, not “the same time tomorrow”. We reproduced exactly that in a Winter ’27 Developer Edition org.

Below you get the current datetime with Datetime.now(), a small helper class that keeps time zones explicit, a methods table with real output, and the test class that proves the DST fix. By the end you will know which parts of the Datetime class in Apex read local time, which read GMT, and when to switch to Date or Time.

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