What is the difference between UUID v4 and v7?

UUID v4 is fully random, while UUID v7 embeds a timestamp in the first 48 bits, making it sortable by creation time. v7 is becoming the preferred choice for database primary keys.

Are these UUIDs truly random?

Yes. We use the browser crypto.randomUUID() API, which provides cryptographically strong random values.

ULID (Universally Unique Lexicographically Sortable Identifier) is a 26-character, base32-encoded ID that combines a timestamp with randomness. It is sortable and URL-safe.

UUID Generator

ID Tools

Generate UUID v4, v7, ULID, and nanoid identifiers

By DevToolHQ teamUpdated 2026-04-15100% client-sideMethodology

100% client-side processing

Quantity (1-100)

About UUID Generator

UUIDs (Universally Unique Identifiers) are 128-bit values formatted as 32 hex digits separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. The v4 variant is the most commonly used — all 128 bits are randomly generated using a CSPRNG, giving a collision probability so low it is effectively impossible in practice. This tool generates UUID v4 using the browser's native crypto.randomUUID() API, which is cryptographically secure and available in all modern browsers and Node.js 14.17+. It also supports UUID v7 (which embeds a millisecond-precision timestamp in the first 48 bits, making it database-friendly and sortable by creation time), ULID (26-character base32, lexicographically sortable and URL-safe), and nanoid (21-character URL-safe format, roughly equivalent collision resistance to UUID v4 but shorter). Use UUID v4 when you need a random, globally unique identifier and sortability is not required — typical for most application entities. Use UUID v7 or ULID for database primary keys where you want index-friendly insertion order without a sequential integer. Use nanoid for short IDs in URLs or public-facing identifiers where readability matters. Bulk generation up to 100 IDs at once is supported for seeding test data.