Developer Time Zone APIs
JavaScript Intl, IANA tzdata, backend handling, and common pitfalls.
Developers should use the **IANA Time Zone Database** (e.g. `America/New_York`), not fixed UTC offsets or "EST" abbreviations. Browsers: **Intl.DateTimeFormat** and **Temporal** (emerging); servers: zoneinfo/tzdata libraries updated regularly (Keeping Time Zone Data Updated).
Common pitfalls
- UTC offset instead of IANA—breaks on DST transition days
- Server OS zone ≠ user zone—store UTC, convert on display
- Same instant globally: Unix Timestamps and UTC
- Ambiguous EST/CST: Time Zone Abbreviation Pitfalls (EST/CST/PST)
Best practices
- APIs return ISO 8601 + IANA id
- Store organizer and attendee zones for meetings
- Unit-test DST boundary dates (March, November)
- IANA overview: What Is the IANA Time Zone Database
Tool: Convert; standard: UTC Basics.