Random UUID v4 Generator
Generate random UUID version 4 identifiers using cryptographic randomness - the most widely used UUID format for general-purpose unique identifiers
Our UUID v4 generator creates purely random universally unique identifiers using cryptographically secure random number generation per RFC 4122 standards. Generate UUID version 4 with 122 random bits for maximum unpredictability and uniqueness. Perfect for database primary keys, API tokens, session identifiers, transaction IDs, and any application requiring random unique identifiers without timestamp or MAC address exposure. Most widely adopted UUID version across modern systems and programming languages.
Related Random Generators
Generate UUID version 7 with Unix timestamp prefix for time-based sortability. Modern alternative combining randomness with chronological ordering.
Generate time-based UUID version 1 with embedded timestamps and node IDs. Sortable by creation time but exposes MAC address.
What is UUID v4?
UUID v4 (Universally Unique Identifier version 4) is a randomly generated identifier defined in RFC 4122 that uses cryptographically secure random number generation to produce 128-bit unique identifiers. Unlike other UUID versions, v4 contains no meaningful information - no timestamps, no MAC addresses, no namespace hashing - just 122 bits of pure randomness (6 bits are reserved for version and variant indicators). This makes v4 the most privacy-friendly UUID version and the de facto standard for general-purpose unique identifier generation in modern software development.
The format follows the standard 32 hexadecimal digits in 5 groups: 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). The version field (4) indicates random generation, while variant bits ensure RFC 4122 compliance. With 2^122 possible values (5.3×10^36), collision probability is astronomically low - you could generate a billion UUIDs per second for 100 years and have less than 50% chance of a single collision. UUID v4 is universally supported across databases (PostgreSQL, MySQL, MongoDB), programming languages (Java, Python, JavaScript, Go), and cloud platforms, making it the safest choice for new projects requiring unique identifiers without special ordering or determinism requirements.
UUID v4 Generator Configuration
Quantity (1-100 UUIDs)
Cryptographic Randomness
RFC 4122 Compliance
Export Formats
How to Generate UUID v4
[STEP 1] Set Quantity
Choose how many UUID v4 identifiers to generate (1-100). Each UUID is independently generated using cryptographically secure randomness, ensuring uniqueness across all identifiers.
[STEP 2] Generate Instantly
Click EXECUTE GENERATION to create random UUIDs. Generation is instant and uses CSPRNG for maximum unpredictability and security. No configuration needed - v4 is purely random with no parameters.
[STEP 3] Copy & Use
Click individual UUIDs to copy them instantly, or use export buttons to download all UUIDs as TXT, CSV, or JSON for database insertion, API integration, or application development.
[STEP 4] Implement
Use UUID v4 for database primary keys, session IDs, API tokens, transaction identifiers, file names, cache keys, or any scenario requiring unique, unpredictable identifiers without timestamp or ordering requirements.
UUID v4 Best Practices
- _ General Purpose Default - UUID v4 is the safest choice for most applications. Use it as your default unless you specifically need time-based sortability (v7) or deterministic generation (v3/v5).
- _ Privacy Friendly - Unlike v1, UUID v4 exposes no MAC addresses or timestamps. Perfect for user-facing identifiers, public APIs, and privacy-sensitive applications.
- _ Database Indexing - While v4 lacks sortability, its randomness prevents index hotspots in distributed databases. For time-series data requiring ordered IDs, consider v7 instead.
- _ Collision Probability - With proper CSPRNG, collision risk is negligible (2^122 possible values). However, always use database unique constraints as defense-in-depth.
- _ API and Tokens - Ideal for session tokens, API keys, OAuth states, and CSRF tokens where unpredictability is crucial. Random nature prevents prediction attacks.
- _ Testing and Development - UUID v4 is perfect for test data and development environments. For deterministic test fixtures requiring reproducible IDs, use v3 or v5 instead.
Technical Implementation
UUID v4 follows RFC 4122 specification, using cryptographically secure random number generation to produce 128-bit identifiers:
// UUID v4 Structure (128 bits total)
Algorithm: Random UUID Generation (CSPRNG)
// Step 1: Generate 128 random bits
random_bytes = CSPRNG(16 bytes / 128 bits)
// Step 2: Set version bits (bits 48-51 = 0100)
random_bytes[6] = (random_bytes[6] & 0x0F) | 0x40
// Step 3: Set variant bits (bits 64-65 = 10)
random_bytes[8] = (random_bytes[8] & 0x3F) | 0x80
// Bit Allocation:
Random bits: 122 bits (maximum entropy)
Version bits: 4 bits (value = 4 = 0100)
Variant bits: 2 bits (value = 10 for RFC 4122)
// Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
// where y ∈ {8, 9, a, b} (variant bits)
Example: 550e8400-e29b-41d4-a716-446655440000
Collision Probability: 1 in 2^122 ≈ 5.3×10^36