Unix Timestamp Converter

A Unix timestamp — also called Epoch time, POSIX time, or simply "seconds since 1970" — is a single integer that pinpoints an exact moment in time. It counts the number of seconds elapsed since midnight UTC on January 1, 1970 (the Unix Epoch), ignoring leap seconds. Right now, the current Unix timestamp is a 10-digit number above 1.7 billion; the same moment in milliseconds is 13 digits.

Developers encounter Unix timestamps everywhere: in database rows, API response payloads, JSON Web Tokens (JWT exp and iat claims), log files, file system metadata, and HTTP headers. The format is universal because it is timezone-free — a single number means the same instant whether your server is in Tokyo or New York.

This converter handles both directions: paste a numeric timestamp (seconds or milliseconds are auto-detected) to see the human-readable date in UTC, ISO 8601, and your local timezone — or enter a date string to get the corresponding Unix timestamp. It also shows relative time ("3 hours ago") for quick sanity checks.

Common pitfalls include mixing up seconds and milliseconds (a 10-digit vs. 13-digit number), the Year 2038 overflow for 32-bit systems, and forgetting that JavaScript's Date.now() returns milliseconds while Python's time.time() returns seconds with a decimal fraction.