What makes UUID v4 a safe choice for primary keys?

UUID v4 uses 122 bits of cryptographic randomness, giving approximately 5.3×10^36 possible values. The probability of a collision when generating even billions of UUIDs is negligibly small.

What is the difference between a UUID and a random string?

A UUID is a 128-bit identifier in a standardized 8-4-4-4-12 hex format. A random string can be any length and character set — useful when you need shorter or URL-safe tokens rather than the full UUID format.

Can I use these UUIDs as database primary keys?

Yes. UUID v4 is widely used as a primary key type in PostgreSQL, MySQL, and MongoDB. Note that random UUIDs can cause index fragmentation in B-tree indexes; ordered UUIDs (like ULIDs or UUID v7) mitigate this.

Generate UUIDs & Random IDs Online

Unique identifiers are needed constantly in software development: database primary keys, idempotency tokens, correlation IDs for distributed tracing, test data fixtures, and API resource identifiers all require values that are statistically guaranteed to never collide. devtoolkit.sh's UUID Generator produces RFC 4122 version 4 UUIDs using cryptographically secure randomness from the browser's Web Crypto API. You can generate one UUID at a time or bulk-generate dozens of them at once and copy the entire list to your clipboard. When you need identifiers that are not in UUID format — shorter strings, alphanumeric codes, or tokens with a custom character set and length — the Random String Generator covers those cases, letting you specify the exact character pool and output length. Both tools run offline in your browser, which means you can generate IDs for sensitive internal systems without the identifiers ever touching an external server.

#UUID GeneratorHOT

Generate random UUIDs (v4) for use as unique identifiers.

RngRandom String Generator

Generate random strings with configurable length and character set.

FAQ

What makes UUID v4 a safe choice for primary keys?: UUID v4 uses 122 bits of cryptographic randomness, giving approximately 5.3×10^36 possible values. The probability of a collision when generating even billions of UUIDs is negligibly small.
What is the difference between a UUID and a random string?: A UUID is a 128-bit identifier in a standardized 8-4-4-4-12 hex format. A random string can be any length and character set — useful when you need shorter or URL-safe tokens rather than the full UUID format.
Can I use these UUIDs as database primary keys?: Yes. UUID v4 is widely used as a primary key type in PostgreSQL, MySQL, and MongoDB. Note that random UUIDs can cause index fragmentation in B-tree indexes; ordered UUIDs (like ULIDs or UUID v7) mitigate this.