Generate cryptographically secure UUID v4, v1 and v7 identifiers in bulk — choose format (lowercase, uppercase, no hyphens, braces) and copy or download the list.
Select UUID v4 (random), v1 (time-based) or v7 (sortable). Choose output format: lowercase, UPPERCASE, no hyphens, or braces.
Enter how many UUIDs to generate — from 1 to 1,000. Useful for seeding databases or generating test fixtures.
Click Copy All to copy every UUID to your clipboard (one per line), or Download to save as a .txt file.
UUID v1 is time-based encoding the current timestamp and MAC address — sortable by time but exposes hardware info. UUID v4 is randomly generated using a cryptographically secure RNG — 122 bits of randomness, the most widely used type. UUID v7 (RFC 9562, 2024) encodes a Unix millisecond timestamp in the first 48 bits making it time-sortable like v1 but without exposing the MAC address — recommended for database primary keys.
UUID v4 UUIDs are generated using the browser crypto.getRandomValues() function providing cryptographically secure random bytes. With 122 bits of randomness the probability of two identical UUID v4 values is approximately 1 in 5.3 times 10 to the power of 36 — effectively zero for any practical application. You would need to generate 1 billion UUIDs per second for 85 years before a 50% chance of collision.
Four output formats: Standard lowercase (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx — the canonical RFC 4122 format), UPPERCASE, No hyphens (32 hex characters without separators, used in some databases and API tokens), and Microsoft-style with curly braces ({xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} — used in Windows Registry, COM/DCOM and .NET).
GUID (Globally Unique Identifier) is Microsoft name for UUID. They are the same 128-bit identifier standard — a GUID is a UUID with a different name, typically formatted with curly braces. All GUIDs are UUIDs. The term GUID is used in Windows, .NET, SQL Server and COM documentation while UUID is used in Unix, RFC 4122 and most web standards.
Yes — UUID v4 is widely used as a primary key especially in distributed systems where multiple nodes generate records independently. The main trade-off vs auto-increment integers is index fragmentation: random UUIDs cause B-tree index pages to insert in random order reducing cache efficiency on large tables. UUID v7 solves this by being time-ordered.
Up to 1,000 UUIDs in a single batch. Enter the quantity and click Generate. All UUIDs appear in a scrollable list with individual copy buttons plus a Copy All button that copies every UUID to clipboard as a newline-separated list. A Download button saves the batch as a .txt file.
Yes — UUID v1 embeds the MAC address of the network interface, exposing identifying information about the server. Sequential values mean IDs generated close together in time are predictable. For security-sensitive applications (user IDs, session tokens, resource identifiers in URLs) always use UUID v4 which is unpredictable and contains no hardware or timing information.
Yes — MySQL uses VARCHAR(36) or BINARY(16) for UUIDs. PostgreSQL has a native UUID type. SQL Server uses UNIQUEIDENTIFIER and expects the curly-brace format. SQLite stores UUIDs as TEXT. Choose No Hyphens format for BINARY(16) storage in MySQL or Standard format for other databases.
The Nil UUID is a special UUID where all 128 bits are zero: 00000000-0000-0000-0000-000000000000. It is used as a null or unset value in UUID contexts, equivalent to null. The Max UUID (ffffffff-ffff-ffff-ffff-ffffffffffff) where all bits are one is used in some range operations. Both are valid per RFC 4122.
UUID v7 encodes the Unix timestamp in milliseconds in the most significant bits, making generated UUIDs naturally sortable by creation time. When used as a database primary key this means new rows insert at the end of B-tree index pages rather than at random positions, dramatically improving write performance and reducing index fragmentation on large high-volume tables.
