What is Unix Epoch Time?
Unix epoch time is a compact way to identify a moment by counting elapsed time from 00:00:00 UTC on January 1, 1970. Because it is numeric, language-neutral, and easy to compare, it is widely used in APIs, databases, logs, analytics events, job queues, and distributed systems. A timestamp can be stored without any display formatting, then rendered later as UTC or as a user's local time zone.
Seconds vs Milliseconds Timestamps
The most common Unix timestamp format is seconds, often shown as a 10-digit number for present-day dates. JavaScript and many browser APIs use milliseconds, which are usually 13 digits. Confusing the two produces dates that look wildly wrong: a seconds timestamp interpreted as milliseconds lands near 1970, while a milliseconds value treated as seconds may point thousands of years into the future. EpochLab automatically detects the usual seconds and milliseconds lengths so you can verify values quickly.
Year 2038 Problem
The Year 2038 problem affects systems that store Unix time in a signed 32-bit integer. That integer reaches its maximum seconds value on January 19, 2038, after which it can overflow and wrap into an invalid or past date. Modern 64-bit systems avoid this limit for practical timelines, but older operating systems, embedded devices, legacy databases, and binary protocols may still need review. When designing new software, prefer storage types that explicitly support long-range timestamps and document whether each value is seconds or milliseconds.