UUIDs explained: generating unique IDs without a database
A practical guide to UUIDs, when version 4 is a good fit, and where randomly generated identifiers belong in an application.
What a UUID is
A UUID (Universally Unique Identifier) is a 128-bit value normally written as five hexadecimal groups, such as 550e8400-e29b-41d4-a716-446655440000. Its huge value space lets applications create identifiers independently with an extremely low chance of a collision.
Why developers use them
UUIDs work well for records created on multiple servers, offline clients and distributed systems because no central counter is required. They also avoid exposing a simple sequence such as order 1042 in a public URL, although that is not a substitute for access control.
Know which version you need
Version 4 UUIDs are random and are a solid default for general-purpose IDs. They do not sort by creation time, so a database with a heavily indexed write path may benefit from a time-ordered identifier strategy. Pick an identifier format based on the database and workflow, not fashion.
Generate IDs when you need them
The UUID Generator creates a fresh batch of version 4 IDs for test fixtures, sample payloads and manual records. Keep production ID generation inside your application so each new record is created consistently.
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