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ToolWrenGenerate one or many random UUID v4 or ULID identifiers, using the browser's cryptographically secure random source. Copy the whole batch with one click.
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UUID is a free, private online tool that lets you generate random UUID v4 and ULID identifiers in bulk with one-click copy. It runs entirely in your browser, so nothing you enter is uploaded to a server.
Privacy: this tool runs entirely in your browser. Your input is never sent to, received by, or stored on any server — there are no uploads and no tracking of what you enter.
A UUID (Universally Unique Identifier) is a 128-bit value written as 32 hex digits in five groups. Version 4 UUIDs are random, making collisions astronomically unlikely — ideal for primary keys and request IDs.
A ULID is a 26-character identifier that is lexicographically sortable by creation time (the first part is a timestamp) while remaining globally unique. It's a popular alternative to UUID v4 when you want time-ordered IDs.
Both use crypto.getRandomValues / crypto.randomUUID, so the values are cryptographically secure, not predictable like Math.random().
A UUID (Universally Unique Identifier) is a 128-bit value, usually shown as 32 hexadecimal digits in five hyphen-separated groups, e.g. 550e8400-e29b-41d4-a716-446655440000. Its purpose is to let many systems generate identifiers independently with effectively no risk of collision — no central coordinator needed. A ULID is a newer 128-bit identifier rendered as 26 Crockford-Base32 characters that is also globally unique but, crucially, sorts by creation time.
There are several UUID versions; version 4 is the one most applications want because it is almost entirely random (122 random bits). The randomness is what makes collisions astronomically unlikely: you could generate billions of v4 UUIDs and never expect a duplicate. This tool uses the browser's cryptographically secure random source (crypto.getRandomValues / crypto.randomUUID), so the values are unpredictable — never the weak, guessable output of Math.random().
Random UUIDs have one drawback: they scatter randomly, which can hurt database performance because new rows insert all over an index. A ULID begins with a millisecond timestamp, so identifiers created around the same time sort together. That gives you time-ordered, index-friendly keys while staying globally unique — a great fit for primary keys, event logs and anything you want to sort chronologically without a separate timestamp column.
Unique identifiers like these are the backbone of distributed systems: database primary keys, request/trace ids in logs, idempotency keys for safely retrying API calls, file and object names, message ids, and correlation ids across microservices. Because each service can mint its own without asking a central authority, UUIDs and ULIDs scale horizontally with no bottleneck.
Set the count to generate many at once — useful for seeding test data or pre-allocating keys. With 122 bits of randomness, v4 UUIDs are unique for all practical purposes; the probability of a collision remains negligible even at enormous volumes. Everything is generated locally, so you can use the output freely without anything being sent to a server.