UUID Generator
Generate UUID v4 or timestamp-based v7 identifiers, format batches, and export them locally.
What this UUID v4 and v7 generator does
This generator creates RFC 9562 UUID version 4 or version 7 values entirely in the browser. Version 4 uses 122 cryptographically random bits. Version 7 stores the current Unix millisecond in its first 48 bits and fills its remaining 74 payload bits from crypto.getRandomValues(). Both set the RFC version and variant fields and use the canonical 8-4-4-4-12 hexadecimal layout.
Choose v4 or v7
Use UUID v4 for an opaque random identifier with no timestamp. Use UUID v7 when records should group chronologically by creation millisecond, which can improve index locality compared with random v4 values. Ordering follows the encoded clock value: same-millisecond random tails are not strictly ordered, and a backward system-clock adjustment can reverse generation order.
Bulk formatting and export
Generate from 1 through 1,000 values, switch hexadecimal letters to uppercase, remove hyphens, or wrap each value in braces for GUID-oriented workflows. Copy the newline-separated result or download the same batch as a UTF-8 text file.
- Create database or application identifiers without coordinating a central counter.
- Populate test fixtures, mock API responses, and sample records.
- Attach correlation IDs to requests, jobs, logs, or messages.
- Prepare small batches for imports, prototypes, and local development.
Format examples
A v4 result can look like 3f2504e0-4f89-41d3-9a0c-0305e82c3301, while a v7 result has 7 as its version nibble, such as 0190b0cc-4f71-7a8e-9c9a-6a74fbb21a92. Uppercase, hyphenless, and brace options change only presentation; downstream parsers may require the canonical lowercase hyphenated form.
Limitations and privacy
UUID uniqueness is probabilistic, and this generator does not check a registry or guarantee uniqueness. UUID v7 exposes its creation millisecond, assumes a non-regressing system clock for generation-order sorting, and random values created within one millisecond are not strictly monotonic. A UUID is an identifier, not automatically a password, API key, or session token. Generation happens locally in the browser; anything you copy, paste, download, transmit, or store is handled by the destination you choose.
Related developer tools
Continue with Password Generator, QR Code Generator, Slug Generator.
How to Use UUID Generator
- Choose UUID v4 for random identifiers or UUID v7 for timestamp-based identifiers.
- Set a quantity from 1 through 1,000 and choose uppercase, braces, or hyphen formatting.
- Select Generate to create the batch locally in your browser.
- Copy the newline-separated values or download them as a UTF-8 text file.
Frequently Asked Questions
What is a UUID?
- UUID (Universally Unique Identifier) is a 128-bit identifier designed to be globally unique without a central issuing authority.
What is UUID v4?
- UUID version 4 is randomly generated. It has 122 random bits and 6 bits for version and variant information.
What is UUID v7?
- UUID version 7 starts with a 48-bit Unix timestamp in milliseconds and uses 74 additional bits for random data. Values with increasing encoded timestamps sort chronologically, but same-millisecond values are randomized and a backward system-clock adjustment can reverse generation order.
Should I choose UUID v4 or v7?
- Choose v4 when you want an opaque random identifier. Choose v7 when timestamp locality and chronological database indexing are useful. Neither version should be treated as a secret.
Are the generated UUIDs cryptographically random?
- The browser cryptography API supplies the 122 random bits in UUID v4 and the 74 random payload bits in UUID v7. UUID v7 also exposes its creation millisecond, so UUIDs are identifiers rather than passwords or tokens.
Sources & references
Primary references: RFC 9562: Universally Unique IDentifiers (UUIDs); W3C Web Cryptography API: getRandomValues().
Last reviewed: