UUID & Timestamp
Generate UUIDs and convert between unix timestamps and dates
Generate UUIDs and convert between unix timestamps and dates
UUIDs (Universally Unique Identifiers) are 128-bit values used anywhere you need an identifier without coordinating with a central database. There are several versions; the two you'll meet most often are v4 (random) and v7 (time-ordered random).
This tool generates UUID v4 using crypto.randomUUID(), which produces 122 bits of randomness — roughly 5.3×10³⁶ possible values. Collisions are effectively impossible for practical use, even across millions of rows per second across many machines. The tradeoff is that v4s are random-ordered, which hurts database insert performance when used as primary keys because B-tree indexes prefer roughly sorted keys. UUID v7 solves this by prefixing a millisecond timestamp, so IDs are time-sortable while still globally unique. If your database supports it, v7 is usually the better choice for new systems.
A Unix timestamp counts the number of seconds since 1970-01-01 00:00:00 UTC, ignoring leap seconds. It's the lingua franca for dates in APIs, databases, and log files because it's timezone-free and trivially comparable. Watch the unit though: different systems expose the same value in seconds, milliseconds, microseconds, or nanoseconds. This tool detects 13-digit values as milliseconds and 10-digit values as seconds automatically.
Systems that store Unix time in a signed 32-bit integer overflow on 2038-01-19 03:14:07 UTC. Modern 64-bit systems and 64-bit timestamp types (BIGINT, PostgreSQL timestamptz) are not affected — but legacy embedded devices and some older C APIs still are.