🆔 UUID Generator

Generate cryptographically secure UUID v4 identifiers instantly. Bulk generation, multiple formats, UUID validator, and random string generator.

🎲 Generated UUID
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⚙️ Format Options
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
📦 Bulk Generation
🔍 UUID Validator
📖 UUID Structure
550e8400-e29b-41d4-a716-446655440000
Time Low (8 hex)

550e8400 — first 32 bits, random in v4

Time Mid (4 hex)

e29b — next 16 bits, random in v4

Version (4 hex)

41d4 — first digit is 4 (version 4)

Variant (4 hex)

a716 — first nibble is 8, 9, a, or b

Node (12 hex)

446655440000 — last 48 bits, random in v4

🔡 Random String Generator
4128
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What is a UUID?

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit label used for identifying resources in computer systems. Defined by RFC 4122, a UUID is typically represented as 32 hexadecimal digits, displayed in five groups separated by hyphens: 8-4-4-4-12 characters. For example: 550e8400-e29b-41d4-a716-446655440000.

UUID version 4 (the most commonly used version) generates all 122 data bits randomly using a cryptographically secure random number generator. The remaining 6 bits encode the version (4) and variant (RFC 4122). The probability of generating two identical UUID v4 values is so small (1 in 5.3 × 10^36) that it can be treated as impossible in practice — making UUIDs suitable as unique keys in databases, distributed systems, file names, and API identifiers without coordination between systems.

How to Use

  1. The page generates a UUID v4 automatically on load — click Copy UUID to copy the single UUID shown at the top.
  2. Use the Format Options to switch between Standard, No Hyphens, Uppercase, or Braces format.
  3. To generate multiple UUIDs, select a quantity (1, 5, 10, 25, 50, or 100) and click Generate. All UUIDs appear in the output area, one per line.
  4. Toggle Auto-refresh to continuously generate a new single UUID every 3 seconds — useful for picking a random one.
  5. Use the UUID Validator to check whether any UUID string is valid and what version it is.
  6. Use the Random String Generator to create custom-length random strings with your chosen character sets.

Key Features

🔐
Cryptographically Secure

Uses crypto.randomUUID() or crypto.getRandomValues() fallback for true cryptographic entropy.

📦
Bulk Up to 100

Generate 1 to 100 UUIDs at once. Download all as a .txt file or copy to clipboard in one click.

🔀
4 Format Options

Standard, no-hyphen, uppercase, and braces-wrapped formats for compatibility with any system.

✅
UUID Validator

Paste any UUID to instantly check if it's valid and identify its version number.

🔡
Random String Generator

Generate random strings of 4–128 characters with custom character sets (upper, lower, numbers, symbols).

🔒
100% Private

All generation happens in your browser. No UUIDs or strings are ever sent to any server.

Frequently Asked Questions

❓ What is the difference between UUID and GUID?
UUID and GUID refer to the same concept. UUID (Universally Unique Identifier) is the name from the open RFC 4122 standard. GUID (Globally Unique Identifier) is Microsoft's term for the same standard. They are structurally identical — 128-bit values formatted as 32 hex digits in 8-4-4-4-12 groups. Microsoft's implementation originally had additional flavours, but in modern usage GUID and UUID v4 are interchangeable.
❓ Is UUID v4 really unique? Can two be the same?
UUID v4 uses 122 bits of random entropy. The total number of possible values is 2^122 ≈ 5.3 × 10^36. To have a 50% probability of generating one duplicate, you would need to generate approximately 2.7 × 10^18 UUIDs. At a rate of one billion UUIDs per second, that would take about 85 years. In any real-world application, UUID v4 collisions are considered impossible.
❓ When should I use UUIDs as database primary keys?
UUIDs are excellent primary keys when you need to generate IDs on the client side before inserting into the database, when you're merging data from multiple sources, or when you don't want to expose sequential integer IDs to end users (which can leak business information). The main trade-off is that UUID v4 keys are not sequential, so they can cause index fragmentation in traditional B-tree indexes. UUID v7 (time-ordered) mitigates this, but v4 is still widely preferred for security-sensitive applications.
❓ What are the different UUID versions?
There are eight UUID versions: v1 uses time and MAC address (not privacy-safe), v2 is DCE Security (rarely used), v3 uses MD5 hashing of a name, v4 is fully random (most common), v5 uses SHA-1 hashing of a name, v6 is a reordered time-based version for better database performance, v7 uses Unix timestamps for sortable UUIDs, and v8 is a custom format for application-specific use. UUID v4 remains the most widely supported and used version.
❓ How is a random string different from a UUID?
A UUID is a specific standard format (128-bit, RFC 4122) with a fixed structure including version and variant bits. A random string is simply a sequence of random characters with no specified format or length constraints. UUIDs are universally recognised and validated by libraries and databases. Random strings are more flexible — useful for tokens, passwords, API keys, or any scenario where you need custom length or character sets without conforming to the UUID standard.