UUID Generator

UUIDs (Universally Unique Identifiers) are 128-bit values designed to be unique across space and time without requiring a central coordination authority. This generator creates Version 4 UUIDs, which are randomly generated using cryptographically secure random number generators (crypto.getRandomValues()).



A UUID is represented as 32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12 (for example: 550e8400-e29b-41d4-a716-446655440000). Version 4 UUIDs have 122 random bits, providing approximately 5.3×10^36 possible unique values. The probability of generating a duplicate is so astronomically small (effectively zero) that UUIDs can be generated independently without coordination.



The generator uses your browser's Web Crypto API to produce truly random values rather than pseudo-random sequences. This ensures UUIDs are unpredictable and suitable for security-sensitive applications like session tokens, database primary keys, or unique identifiers in distributed systems where multiple servers generate IDs independently.

1. Database Primary Keys
UUIDs make excellent primary keys in distributed databases where multiple servers insert records simultaneously. Unlike auto-incrementing integers, UUIDs are generated client-side without database coordination, preventing conflicts. They're ideal for microservices architectures, distributed systems, and offline-first applications that sync later.



2. API Request & Session Identifiers
Generate unique request IDs for API calls to enable tracing, logging, and debugging across distributed services. Each HTTP request gets a UUID that follows it through multiple microservices, making it easy to correlate logs. Session tokens also use UUIDs to uniquely identify user sessions without predictability.



3. File & Resource Naming
Avoid filename collisions when users upload files by generating UUID-based filenames. Instead of "photo.jpg" (which conflicts if multiple users upload), use "550e8400-e29b-41d4-a716-446655440000.jpg". This prevents overwrites and creates unguessable URLs, adding security through obscurity for private resources.



4. Message Queue & Event IDs
Event-driven architectures and message queues (Kafka, RabbitMQ, AWS SQS) use UUIDs to uniquely identify messages and events. This enables deduplication, exactly-once processing, and tracking message flows through complex distributed systems with multiple producers and consumers.



5. URL Shortener & Temporary Links
Generate short, random URLs for password reset links, email verification, or file sharing. UUIDs (especially their short hash versions) create unguessable URLs that expire after use. The randomness prevents attackers from predicting or enumerating valid links, unlike sequential IDs.

• UUID v4 vs other versions: Version 4 (random) is most common for general use. Version 1 includes timestamps and MAC addresses (potential privacy issue). Version 5 creates UUIDs from namespaces and names (deterministic). For most applications, v4 is the right choice.



• Store UUIDs efficiently: Store UUIDs as BINARY(16) or UUID native types in databases, not as VARCHAR(36) strings. This saves 20 bytes per record and improves index performance. Convert to string format only when displaying to users.



• Use UUIDs for public-facing IDs: Sequential integer IDs expose business metrics (competitor can infer order volume by ID gaps) and enable enumeration attacks. UUIDs prevent ID guessing and hide growth metrics from competitors or malicious actors.



• Generate on client-side when possible: UUIDs can be safely generated client-side (browser, mobile app) before sending to servers. This reduces server load, enables offline functionality, and allows optimistic UI updates without waiting for server responses.



• Index considerations: Random UUIDs cause poor database index performance compared to sequential IDs due to random insertions. Consider ordered UUIDs (ULID, time-ordered UUIDs) for high-throughput write scenarios or use UUIDs only where randomness is required.



• Don't rely on UUIDs for security alone: While UUIDs are unguessable, they're not cryptographically strong secrets. Don't use raw UUIDs as authentication tokens without additional security measures (signatures, encryption, expiration).



• Bulk generation for testing: Need test data? Generate hundreds of UUIDs at once for database seeding, API testing, or development fixtures. Much faster than generating one at a time.