UUID Generator
Generate cryptographically secure UUID v4 identifiers instantly — no server, no signup, no limits.
UUID Generator
Powered bycrypto.getRandomValues()
All UUIDs generated locally in your browser. Nothing is sent to any server.
Your UUIDs will appear here.
Set a quantity and click Generate.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify information in computer systems without centralized coordination. It is standardized by RFC 4122 and represented as a 32-character hexadecimal string split into 5 groups separated by hyphens.
Length
36 characters — 32 hex digits + 4 hyphens
Randomness
122-bit entropy — ~5.3 × 1036 possible values
Standard
RFC 4122 — also ITU-T X.667 and ISO/IEC 9834-8
What is a UUID?
A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit label standardized by the Internet Engineering Task Force under RFC 4122.
UUIDs are designed to be unique across all time and space without requiring a central registration authority. Two independently generated UUIDs can be assumed to be distinct, thanks to their extreme statistical uniqueness.
- 128 bits = 16 bytes of data
- Represented as 32 hex digits + 4 dashes (36 chars)
- Case-insensitive — upper or lowercase are equivalent
- Supported natively in PostgreSQL, MySQL, MongoDB, and more
UUID Format
32 bits
16 bits
16 bits
16 bits
48 bits
The 13th character encodes the version (e.g. 4 for v4).
The 17th character (after 3rd dash) encodes the variant.
UUID Versions Compared
There are several UUID versions, each suited to different use cases.
| Version | Generation Method | Best For | Requires |
|---|---|---|---|
| v1 | MAC address + timestamp | Time-ordered logging — UUID v1 Generator → | Network interface |
| v2 | DCE Security (POSIX UID/GID) | Legacy DCE systems | System identity |
| v3 | MD5 hash of namespace+name | Deterministic IDs from names — UUID v3 Generator → | Namespace UUID + input |
| v4 | Cryptographically random | General purpose — most common — UUID v4 Generator → | Nothing (this tool) |
| v5 | SHA-1 hash of namespace+name | Deterministic IDs (secure) | Namespace UUID + input |
| v6 | Reordered timestamp (RFC 9562) | Sortable time-based IDs | Clock + node |
| v7 | Unix timestamp + random (RFC 9562) | Database-friendly sortable IDs | Nothing (modern standard) |
Example UUIDs Generated Today
Fresh UUID v4 examples generated client-side on page load. Click any to copy.
How This UUID Generator Works
This tool generates UUID v4 values entirely inside your browser using the Web Crypto API (crypto.getRandomValues()), which produces cryptographically secure pseudo-random numbers — the same level of randomness used in encryption.
No data leaves your device. The generation algorithm follows RFC 4122 §4.4:
- Fill 16 bytes with cryptographically secure random data
- Set bits 12–15 of byte 6 to
0100(version 4) - Set bits 6–7 of byte 8 to
10(RFC 4122 variant) - Format as
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
Common Use Cases
UUIDs are the preferred unique identifier for:
Frequently Asked Questions
Concise answers about UUIDs and this generator tool.
xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Example: 550e8400-e29b-41d4-a716-446655440000.
550e8400-e29b-41d4-a716-446655440000. It consists of 32 hexadecimal digits (0–9 and a–f) arranged in the pattern 8-4-4-4-12 separated by hyphens. The format is case-insensitive; uppercase and lowercase are equivalent.
crypto.getRandomValues() API, which is cryptographically secure. All generation happens locally in your browser — no data is sent to any server, and the generated UUIDs are never logged, stored, or transmitted.
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