UUID v1 Generator

While UUID v4 is random and provides no information about creation time, UUID v1 encodes a timestamp directly into the identifier. This makes it possible to extract when a UUID was generated just by looking at the UUID itself. In systems where chronological ordering or timestamp extraction is valuable, UUID v1 is the right choice.

Time-based structure

UUID v1 uses 60 bits to store a timestamp (measured in 100-nanosecond intervals since October 15, 1582). The remaining bits include a version identifier and a node value (traditionally the MAC address of the machine that generated it, but here a random value for privacy). This design means each UUID v1 contains a hidden creation timestamp that you can decode.

Automatic ordering

UUIDs generated in sequence have monotonically increasing timestamp portions, so they naturally sort chronologically. This can be more efficient for database indexing than random UUIDs—sequential access patterns are faster than random ones. Some databases optimize for this behavior, making UUID v1 preferable for certain use cases.

Privacy considerations

Classic UUID v1 implementations use the MAC address of the generating machine, which reveals information about your hardware to anyone who sees the UUID. This tool uses a random node identifier instead, preserving the timestamp benefit while avoiding privacy leaks. If you need MAC-address-based UUIDs for specific interoperability reasons, you'll need a different tool.

Decoding the timestamp

One unique feature of this tool is timestamp decoding. Generate a UUID v1, and the tool also shows when it was created. This is useful for auditing and debugging—you can determine from the UUID alone when something was generated. For UUID v4 (random), no such extraction is possible.

When to use v1 vs. v4

Prefer UUID v1 when ordering by creation time matters and you want that information encoded in the ID. Prefer UUID v4 when privacy and true randomness are more important.