How to Generate UUIDs & ULIDs Online
Create unique identifiers in four simple steps:
Select Algorithm
Choose UUID v4 (random), UUID v7 (time-ordered), or ULID.
Choose Quantity
Generate 1 single ID or bulk batches up to 500 identifiers.
Format Output
Toggle hyphens, UPPERCASE hex letters, or JSON string quotes.
Copy or Export
1-click copy to clipboard or download a formatted `.txt` list.
Key Features & Collision Safety
Cryptographically Secure
Powered by browser Web Crypto API random number generators for zero duplicate collisions.
UUIDv7 & ULID Sortability
Time-ordered keys optimize database indexing and eliminate page fragmentation.
Bulk Generation up to 500
Generate hundreds of unique primary keys in milliseconds with zero lag.
100% In-Browser Privacy
Generated IDs stay local in client memory without logging to external servers.
Flexible Formatting
Remove hyphens for compact 32-char hex or wrap in double quotes for JSON arrays.
1-Click TXT Export
Download bulk ID lists for database seed scripts and unit testing.
Comparing UUID v4, UUID v7, and ULID for Distributed Systems
While standard UUID v4 provides $2^122$ possible random combinations, random keys cause heavy database index thrashing in PostgreSQL, MySQL, and MongoDB. Modern distributed applications increasingly adopt UUID v7 (RFC 9562) and ULID, which encode creation timestamps into the most significant bits for sequential indexing while preserving cryptographic uniqueness.
Nextgen Astra UUID Generator offers the fastest, most versatile in-browser generator for both legacy and time-ordered standards.
Comparison Matrix
| Algorithm | UUID v7 (Recommended) | UUID v4 | ULID |
|---|---|---|---|
| Sortability | Yes (Chronological Time) | No (Random) | Yes (Base32) |
| Standard | IETF RFC 9562 | IETF RFC 4122 | De-facto Spec |
| B-Tree Index Friendly | Optimal | High Fragmentation | Optimal |
| Privacy / Security | 100% In-Browser | 100% In-Browser | 100% In-Browser |
Frequently Asked Questions
?What is a UUID and how is it generated?
A Universally Unique Identifier (UUID) is a 128-bit label used for database keys and distributed systems. This tool uses native Web Crypto API (`crypto.randomUUID`) to generate cryptographically secure, collision-resistant random identifiers.
?What is the difference between UUID v4, UUID v7, and ULID?
UUID v4 is completely random. UUID v7 and ULID combine a 48-bit millisecond timestamp with random entropy, making them lexicographically sortable, which dramatically improves database B-tree index performance.
?Can I generate bulk UUIDs (up to 500 at once)?
Yes! Select your desired batch count (1 to 500), customize hyphens and quotes, and click 'Copy All' or 'Download .TXT'.
?Are the generated UUIDs safe for production databases?
Yes! All IDs follow official RFC 4122 (v4), RFC 9562 (v7), and Crockford Base32 (ULID) standards.
?Is any data sent to an external server?
No! All UUID generation occurs 100% locally inside your web browser CPU.