Unix Timestamp Converter

What is a Unix Timestamp?

A Unix timestamp (also called Epoch time or POSIX time) counts the number of seconds since January 1, 1970, 00:00:00 UTC. It provides a timezone-independent way to represent a specific moment in time as a single integer, making it ideal for databases and APIs.

Seconds vs Milliseconds

Traditional Unix timestamps use seconds (10 digits, e.g., 1712000000). JavaScript and many modern APIs use milliseconds (13 digits, e.g., 1712000000000). This tool auto-detects both formats and converts them correctly to human-readable dates in UTC, local time, and ISO 8601 format.

Common Use Cases

Timestamps appear in API responses, database records, log files, JWT tokens, and system event logs. Developers frequently need to convert between timestamps and human-readable dates when debugging, analyzing logs, or working with time-series data across different time zones.

Frequently Asked Questions

What is the difference between seconds and milliseconds timestamps?

Traditional Unix timestamps count seconds since January 1, 1970 and are 10 digits long (e.g., 1712000000). JavaScript and many modern APIs use milliseconds, which are 13 digits long (e.g., 1712000000000). This tool auto-detects the format based on the number of digits and converts both correctly.

Why do timestamps start from January 1, 1970?

January 1, 1970, 00:00:00 UTC is called the Unix Epoch. It was chosen by the creators of the Unix operating system as an arbitrary but practical starting point. All Unix-based systems (Linux, macOS, Android) and most programming languages use this reference point. Timestamps before this date are negative numbers.

How do timestamps handle time zones?

Unix timestamps are always in UTC (Coordinated Universal Time) and are timezone-independent. This is their primary advantage — the same timestamp represents the same moment in time regardless of where you are. When displaying timestamps, the local timezone offset is applied during conversion to human-readable dates.

Where do I find timestamps in my work?

Timestamps appear in API responses (especially REST APIs), database records (MySQL, PostgreSQL created_at columns), JWT tokens (iat and exp claims), log files, Git commit dates, file system metadata, and browser cookies. This tool helps you quickly decode these values during debugging.