UUID Generator

Developers need identifiers that are unique, copy-safe, and fast to produce in volume. A UUID generator (also called a GUID generator on Windows and .NET) outputs 128-bit values in standard string forms — hyphenated, compact, or wrapped in braces. HitRandom covers the cases single-ID bookmarklets skip: bulk UUID generation up to 1000 per click, UUID v7 for time-ordered database keys, and format toggles for lowercase, uppercase, hyphens, and Microsoft GUID braces.

UUID v4 — random (default): The common choice for primary keys, correlation IDs, and file names. v4 sets version nibble 4 and RFC 4122 variant bits on cryptographically random bytes. HitRandom calls crypto.randomUUID() when the browser supports it, otherwise builds v4 from crypto.getRandomValues() with correct version and variant masking — never Math.random().

UUID v7 — time-ordered: RFC 9562 v7 embeds a 48-bit Unix millisecond timestamp in the leading bytes and fills the remainder with random data. The result sorts chronologically in B-tree indexes — useful in PostgreSQL, event stores, and anywhere insert locality beats pure randomness. Few online generators expose v7; it is a practical differentiator when you need ordered IDs without a central allocator.

UUID v1 and Nil: v1 combines a timestamp with a random node ID (multicast bit set per spec) for legacy systems that still expect time-based UUIDs. Nil UUID (00000000-0000-0000-0000-000000000000) is the all-zeros sentinel used in APIs and schemas to mean “no identifier.” Namespace-hashed v3/v5 are intentionally omitted — they require namespace UUID plus name inputs and are rarely needed in quick dev workflows.

Bulk generation for seeding: Set quantity above 1 to generate multiple UUIDs at once — seed a test database, fill a CSV column, or provision batch resources without looping a one-at-a-time tool. Small batches display as copy-able rows; larger batches open in text view with the same copy formats as our other tools (comma-separated, one per line, JSON, tab-separated). Nothing is written to disk or stored in history.

Format options: Lowercase hex is the default. Switch to uppercase for systems that expect it. Disable hyphens for a 32-character compact string. Enable braces for GUID syntax. All formatting is applied to the same underlying bytes — toggling case or hyphens after generation reformats the current batch without regenerating new random values.

Who uses this: Backend developers assigning primary keys, QA engineers building test fixtures, data engineers preparing seed files, and anyone who needs a trustworthy generate uuid workflow without installing CLI tools or signing into a service. Pair with HitRandom’s Password Generator and Random Number Generator in Generators & Security.