Create random UUID v4 values for databases, APIs, test data and app development.
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A UUID (Universally Unique Identifier) is a 128-bit identifier used to label records, users, sessions, transactions, files, and API objects without relying on a central numbering authority. UUID v4 values are randomly generated, making collisions statistically impossible — even across distributed systems with billions of records.
This tool generates UUID v4 strings instantly in your browser using the crypto.randomUUID() API where available. Generate one at a time or up to 100 in bulk for seeding databases, writing test fixtures, populating mock API responses, or any development workflow that needs unique identifiers fast.
Enter how many UUIDs you need — from 1 to 100. For most one-off tasks, 1 is enough. For database seeding or test fixtures, generate the full batch at once.
UUIDs are created instantly in your browser using cryptographically secure randomness. No server request is made.
Click "Copy All" to copy every generated UUID to your clipboard. Paste into your code, SQL seed file, API request body, or test fixture directly.
UUID v4 is the most common UUID format. It is randomly generated — 122 of its 128 bits are random. The format is: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is random hex and y is one of 8, 9, a, or b. There are over 5 undecillion (5.3 × 10³⁶) possible v4 UUIDs.
UUID v1 uses the current timestamp and MAC address — sortable but potentially privacy-sensitive. UUID v4 is fully random — most widely used for general IDs. UUID v7 (newer) uses a timestamp prefix for database-index-friendly sorting while remaining largely random.
Yes, for all practical purposes. The probability of generating two identical UUID v4 values is approximately 1 in 5.3 × 10³⁶ — so low that collisions are not a real concern in any application, even at massive scale.
Yes. UUIDs are excellent primary keys for distributed systems where multiple nodes insert records simultaneously without coordination. The trade-off is that random UUIDs cause index fragmentation in B-tree indexes. UUID v7 or ULID are better choices if insert-order performance matters.
No. UUIDs are generated entirely in your browser using JavaScript's crypto API. Nothing is sent to any server and nothing is logged.
GUID (Globally Unique Identifier) is Microsoft's term for UUID. They are the same standard — UUIDs are used in web, Linux, and macOS contexts; GUIDs in Windows, .NET, and SQL Server contexts. The format and specification are identical.