UUID v4 Generator
Generate up to 500 RFC 4122 compliant Version-4 UUIDs at once using the browser's native `crypto.getRandomValues()` API. Supports uppercase, lowercase, and hyphen toggles.
What is the UUID v4 Generator?
This tool generates cryptographically secure Universally Unique Identifiers (UUIDv4) and timestamp-ordered UUIDv7 identifiers in bulk directly inside your browser.
RFC 4122 Cryptographic Entropy and Bit-Level Masking
A UUID is a 128-bit number represented as 32 hexadecimal digits separated by hyphens (8-4-4-4-12 format). In UUIDv4, 122 bits are filled with pure cryptographic randomness provided by the operating system via Web Crypto API. Bits 48–51 are fixed to 0100 (version 4), and bits 64–65 are fixed to 10 (RFC 4122 variant). UUIDv7 replaces the first 48 bits with a Unix timestamp in milliseconds, ensuring that generated keys naturally sort in chronological order.
How to Use the UUID v4 Generator
Select Version & Quantity
Choose UUIDv4 (random) or UUIDv7 (time-ordered), and specify how many identifiers you need (up to 1,000 at once).
Configure Formatting
Toggle hyphens (standard 36-character vs compact 32-character) and choose uppercase or lowercase output.
Generate & Copy
Click "Generate UUIDs", then use the one-click copy button or download the batch as a .txt or .csv file.
Key Settings & Parameters
| Setting | What It Controls | Recommended Default |
|---|---|---|
| UUID Version (v4 vs v7) | UUIDv4 is purely random; UUIDv7 includes a 48-bit millisecond timestamp for database index clustering. | UUIDv7 for database primary keys, UUIDv4 for general secrets and tokens |
| Hyphens | Standard format includes 4 hyphens (36 chars); compact format removes hyphens (32 chars). | Standard (with hyphens) for RFC compliance |
Common Pitfalls to Avoid
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• Using Math.random() to generate UUIDsMath.random() is predictable and non-cryptographic, creating severe collision risks. Ripitoo uses window.crypto.getRandomValues() for hardware-level entropy.
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• Using UUIDv4 as clustered primary keys in massive databasesRandom UUIDv4 causes index fragmentation and cache thrashing. Use UUIDv7 or BIGSERIAL/BIGINT identity columns for high-throughput tables.
Pro Tips for Best Results
- Use UUIDv7 in modern PostgreSQL 16+ or SQLite applications: you get the distributed uniqueness of UUIDs with the index performance of auto-incrementing integers.
Local Processing Guarantee
Generated UUIDs exist only in your browser memory. Ripitoo does not log, transmit, or store generated identifiers.
When to Use
- Creating distributed primary keys in PostgreSQL, MySQL, CockroachDB, and MongoDB.
- Generating API idempotency keys for payment gateways like Stripe.
- Generating unique tracking correlation IDs (trace IDs) across microservices.
Short public URLs where brevity is paramount (use a 7-character NanoID or short hash for that).
- • Generates batches up to 1,000 UUIDs per click in the browser interface to prevent clipboard and DOM freezing.