The Dev Tools - Free Online Developer Utilities

Unix Timestamp (in seconds):

About Unix Timestamps

A Unix timestamp (also known as POSIX time or Epoch time) represents the number of seconds that have elapsed since January 1, 1970, 00:00:00 UTC, not counting leap seconds. This standardized time format is widely used in programming, databases, and system operations for its simplicity and timezone independence.

Common Use Cases

Database Timestamps: Storing event times and dates
API Responses: Standardized time format for data exchange
File Systems: Recording file modification times
Log Files: Tracking when events occurred
Cache Control: Managing expiration times
Session Management: Tracking user sessions
Scheduling: Planning future events and tasks

Tips

Always store timestamps in UTC
Consider timezone differences in display
Use appropriate precision (seconds vs milliseconds)
Validate input ranges
Handle DST transitions carefully

Understanding Unix Time

Epoch: January 1, 1970, 00:00:00 UTC (the Unix Epoch)
Unit: Seconds (some systems use milliseconds)
Range: Can represent dates from 1901 to 2038 (32-bit systems)
Timezone: Always in UTC, converted locally as needed
Format: Single integer number (e.g., 1632152400)

Key Concepts

Timezone Independence: Same timestamp represents same moment globally
Leap Seconds: Not counted in Unix time
Y2K38 Problem: 32-bit timestamp limit (use 64-bit for dates beyond 2038)
Millisecond Precision: Often used in JavaScript (multiply by 1000)
Negative Values: Represent dates before the Unix Epoch

Conversion Tips

To Timestamp: Convert local time to UTC, then to seconds
From Timestamp: Convert seconds to UTC, then to local time
JavaScript: Date.now() returns milliseconds (divide by 1000)
Database: Most databases have built-in timestamp functions
Formatting: Use locale-aware formatting for display

Common Pitfalls

Confusing seconds with milliseconds
Ignoring timezone conversions
Not handling invalid inputs
Assuming all days have 24 hours (DST changes)
Using 32-bit timestamps for future dates