UUID Generator - Generate RFC 4122 v4 UUIDs Online
A Universally Unique Identifier (UUID, also known as GUID) is a 128-bit identifier standardized under RFC 4122. UUID Version 4 uses 122 bits of pseudo-random entropy. In distributed architectures and microservices, relying on sequential database auto-increment IDs causes coordination bottlenecks and reveals business metrics. UUID v4 solves this by enabling distributed systems to generate globally unique primary keys without central coordination.
When to Use This Tool
- Distributed Database Primary Keys: Assign conflict-free primary keys (PKs) in distributed databases like MongoDB, DynamoDB, or CockroachDB.
- Distributed Tracing & Request IDs: Tag API requests with an "X-Request-ID" header to trace transactions across microservice logs.
- Mock & Seed Data Generation: Populate test database seed scripts with realistic, non-colliding unique record identifiers.
- Preventing Enumeration Attacks: Replace sequential integer URLs (/users/1024) with unguessable UUIDs (/users/a8098c1a-...) to protect user privacy.
How to Use
- Select Quantity: Choose how many UUIDs you want to generate in a single batch (1 to 100).
- Configure Format: Toggle hyphens (8-4-4-4-12) or remove them for compact 32-character strings.
- Choose Casing: Select standard lowercase or uppercase hexadecimal output.
- Copy or Export: Copy all generated UUIDs with one click or export them as JSON/CSV arrays.
Input & Output Example
Input:
Quantity: 1, Format: Hyphenated, Case: Lowercase
Output:
f47ac10b-58cc-4372-a567-0e02b2c3d479
Frequently Asked Questions (FAQ)
Q. Can two UUID v4 values ever collide?
A. Mathematically, the probability of a UUID v4 collision is virtually zero. You would need to generate approximately 1 billion UUIDs per second for roughly 85 years before the probability of a single collision reaches 50%.
Q. What do the version and variant bits represent?
A. In standard UUID v4, the 13th character is always "4" (representing version 4 random), and the 17th character begins with 8, 9, a, or b (indicating the RFC 4122 variant bits).
Q. Is crypto.randomUUID() supported in all browsers?
A. Yes. Modern web browsers support the native crypto.randomUUID() API, delivering hardware-entropy backed random identifiers with sub-millisecond execution.
Engineering & Privacy Notes
- Strictly complies with IETF RFC 4122 UUID Version 4 specification.
- Runs completely offline on client-side memory with zero external logging.
Related Developer Tools
- Hash Generator: Generate cryptographic hash fingerprints from UUIDs.
- Password Generator: Generate high-entropy random credentials.
- JWT Decoder: Inspect UUID-formatted "sub" and "jti" claims inside tokens.
- Diff Checker: Compare UUID lists and detect missing or duplicate keys.