Version 4 · Cryptographically random · Bulk generation
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GUID Generator
Free online UUID and GUID generator. Generate single or bulk UUIDs (version 4, random) using the browser's built-in crypto API. Copy in standard, uppercase, or no-hyphen format. Fully client-side.
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A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hex digits in 8-4-4-4-12 groups (e.g. 550e8400-e29b-41d4-a716-446655440000). UUID v4 is randomly generated, making collisions statistically impossible — the chance of generating two identical v4 UUIDs is 1 in 2¹²². They are used as primary keys in databases, request IDs in distributed systems, file names, and correlation IDs in logs.
This tool generates v4 UUIDs using the browser's crypto.randomUUID() API where available, falling back to crypto.getRandomValues(). Generate one or a batch, and copy them individually or all at once.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify objects in computer systems. UUIDs are written as 32 hexadecimal digits in the format 8-4-4-4-12, e.g. 550e8400-e29b-41d4-a716-446655440000. They're used as database primary keys, session IDs, and file names.
What's the difference between UUID v4 and other versions?
UUID v4 is random — all 122 bits are generated randomly, making collisions virtually impossible (1 in 2^122 chance). UUID v1 uses your MAC address and timestamp (a privacy risk). UUID v3/v5 are deterministic, derived from a name using MD5 or SHA-1. For most use cases, v4 is the right choice.
What's the difference between UUID and GUID?
GUID (Globally Unique Identifier) is Microsoft's implementation of UUID — they're the same format and interchangeable in most contexts. GUIDs are often written in uppercase with curly braces: {550E8400-E29B-41D4-A716-446655440000}.
Can two generated UUIDs ever be the same?
Theoretically possible but statistically near-impossible. UUID v4 uses 122 random bits giving 5.3×10³⁶ possible values. The probability of collision after generating 1 billion UUIDs per second for 100 years is approximately 50% — so in practice, treat UUIDs as globally unique.
How do I generate a UUID in code?
JavaScript/Node.js: crypto.randomUUID(). Python: import uuid; str(uuid.uuid4()). PHP: wp_generate_uuid4() or com_create_guid(). Java: UUID.randomUUID().toString(). C#: Guid.NewGuid().ToString(). Ruby: SecureRandom.uuid. All modern languages have built-in UUID support.
What is UUID v7 and when should I use it?
UUID v7 (RFC 9562, 2024) embeds a millisecond-precision Unix timestamp in the first 48 bits, making UUIDs sortable by creation time. This is ideal for database primary keys because sorted UUIDs prevent index fragmentation. Use v4 for random IDs with no order requirement, v7 when you need time-ordered IDs.
Is UUID the same as a GUID?
GUID (Globally Unique Identifier) is Microsoft's name for UUID. They are technically identical — both are 128-bit values in 8-4-4-4-12 hex format. The terms are interchangeable. Windows and .NET SDKs use GUID, while web standards, databases, and most other platforms use UUID.