UUID Generator
Generate random UUID v4 values instantly — single or bulk.
Format
Bulk Generate
Validate UUID
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How to Use the UUID Generator
- Click Generate UUID to create a single random UUID v4.
- Choose a format: with hyphens, without hyphens, or uppercase.
- Use the Bulk Generate slider to generate up to 100 UUIDs at once.
- Paste any UUID in the Validate section to check if it is a valid UUID format.
UUIDs (Universally Unique Identifiers) are 128-bit values used to uniquely identify resources in databases, APIs, and distributed systems.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. It is represented as 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUID v4 uses random numbers, making the probability of generating the same UUID twice astronomically low — approximately 1 in 5.3 × 10³⁶.
All UUIDs are generated in your browser using the crypto.randomUUID() API — no data is sent to any server.
Common Use Cases
- Database primary keys: Use UUIDs instead of sequential integers to avoid exposing record counts and enable merging of distributed databases
- API request IDs: Attach a UUID to each API request for tracing and deduplication across microservices
- Session tokens: Generate secure session identifiers that are not guessable
- Distributed systems: Multiple services can generate IDs independently without coordination or conflicts
- File naming: Use UUIDs as unique filenames when uploading user content to avoid collisions
FAQ
What is UUID v4?
UUID v4 is randomly generated. It uses 122 random bits (6 bits are fixed for the version and variant). There are other UUID versions: v1 is based on timestamp and MAC address, v3 and v5 are name-based using MD5 and SHA-1 respectively. v4 is the most commonly used because it requires no coordination and leaks no identifying information.
What is the difference between UUID and GUID?
There is no technical difference. GUID (Globally Unique Identifier) is Microsoft's term for UUID, used in COM, .NET, and Windows APIs. Both refer to the same 128-bit identifier format defined by RFC 4122. The terms are used interchangeably in practice.
How unique is a UUID v4?
Extremely unique. UUID v4 has 122 random bits, giving 2¹²² (approximately 5.3 × 10³⁶) possible values. To have a 50% chance of a collision, you would need to generate about 2.7 × 10¹⁸ UUIDs. At a rate of 1 billion UUIDs per second, that would take over 85 years.
What is the format of a UUID?
A UUID is formatted as 8-4-4-4-12 hexadecimal characters separated by hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The 4 in the third group indicates UUID version 4. The y in the fourth group is one of 8, 9, a, or b, indicating the variant. Total length: 36 characters including hyphens, 32 without.
When should I use UUID vs auto-increment?
Use UUID when: you need to generate IDs on the client or across multiple services, you don't want to expose record counts, or you need to merge data from multiple sources. Use auto-increment (sequential integers) when: you want the smallest possible storage (4–8 bytes vs 16 bytes), query performance on indexed columns is critical, or ID readability matters for debugging.