UUID & CUID Generator

ID Generator

Generate batch unique identifiers: RFC 4122 v4 UUIDs, time-ordered v7 UUIDs, and collision-resistant CUIDs.

Processed 100% locally in your browser

Quantity (5):

Generated V4 List5 identifiers

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Technical Documentation & Reference

Complete Guide to UUID Standards, Time-Ordering & Collision Prevention

Compare RFC 4122 UUID v4, time-ordered UUID v7, and collision-resistant CUIDs for database primary keys and distributed architectures.

A Universally Unique Identifier (UUID) is a 128-bit label used for information in computer systems, standardized in RFC 4122. In modern distributed systems, generating unique keys on the client or application layer rather than waiting for sequential database auto-increment IDs eliminates database lock contention and coordinates distributed writes seamlessly.

UUID v4 vs. Time-Ordered UUID v7

While UUID v4 is purely random (providing 122 bits of cryptographic entropy), its random distribution causes severe database performance degradation in clustered indexes (B-trees in PostgreSQL, MySQL, SQLite) due to frequent index page splits. UUID v7 addresses this by prefixing 48 bits of Unix epoch timestamp with 74 bits of randomness, combining time-sorted locality for blazing index lookups with guaranteed global uniqueness.

How to Use This Tool

Select Identifier Type

Choose between RFC 4122 UUID v4 (random), UUID v7 (time-ordered), or CUID (collision-resistant web ID).

Specify Quantity

Generate a single unique identifier or batch generate up to hundreds of IDs simultaneously.

Choose Formatting Options

Toggle hyphens, uppercase or lowercase letters, and array or newline delimiters.

Copy or Download Batch

Copy IDs directly to your clipboard or download them as a CSV/JSON text file.

Key Features & Capabilities

Web Crypto API Security

Generates randomness exclusively using window.crypto.getRandomValues for cryptographically secure entropy.

Time-Ordered UUID v7

Includes modern timestamp-ordered UUID v7 for optimal database index insertion speeds.

Batch Generation Support

Generate hundreds of unique IDs in a split second without UI lag.

100% In-Browser Privacy

Generated IDs are never stored, transmitted, or logged on remote servers.

Frequently Asked Questions

What is the chance of a UUID v4 collision?

The probability of a collision is astronomically low. To have a 50% chance of a single collision, you would need to generate over 2.7 quintillion (2.7 x 10^18) UUIDs.

Why should I use UUID v7 instead of UUID v4 in databases?

UUID v7 includes a 48-bit millisecond timestamp at the beginning of the identifier. Because new records naturally sort sequentially, database B-tree indexes append them sequentially, avoiding random disk I/O and page fragmentation.

What is a CUID?

A CUID (Collision-resistant Unique Identifier) is an ID optimized for horizontal scaling in distributed web applications, combining timestamps, host fingerprints, process IDs, and random counters.

Are generated UUIDs cryptographically random?

Yes. JSON Studio uses the browser Web Crypto API (crypto.getRandomValues), providing cryptographically strong pseudo-random numbers.

Privacy & Security Guarantee

All data processing, AST syntax repairs, and cryptographic operations happen 100% locally inside your browser using native JavaScript and WebAssembly. No inputs, keys, or file payloads are ever transmitted to or stored on remote servers.