Timezone Handling Guide: Store UTC, Display Local
Best practices for timezone-aware applications. Store timestamps in UTC, convert at display time, and avoid common timezone bugs in web apps.
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Tags: developer-tools, timestamps, timezones
Timezone Handling Guide: Store UTC, Display Local in Every Stack Bad timezone handling causes bugs that only surface at specific hours, in specific locations, or during daylight saving transitions — making them genuinely hard to reproduce and diagnose. The fix is a simple rule that eliminates most timezone bugs before they happen: store UTC, display local. This guide implements that rule across JavaScript, Python, SQL, and common backend patterns. --- The Golden Rule Store all timestamps in UTC. Convert to local time only when displaying to users. Every function that stores, queries, or transmits timestamps should work in UTC. Every function that renders a timestamp for a human should convert to their local time. If you follow this rule consistently, timezone bugs become rare. If you…
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