UUID Generator

UUID Generator Overview

A UUID (Universally Unique Identifier) is a 128-bit identifier used for database primary keys, distributed IDs, client-side temporary keys, and more. RFC 4122 defines common versions, including random UUID v4 and time-ordered UUID v7 (RFC 9562).

This tool generates UUIDs entirely in your browser. It supports single generation, batch generation (up to 1,000), and format validation. Nothing is uploaded to a server.

Features

1. Single generation: Choose v4 or v7, uppercase/lowercase, with or without hyphens
2. Batch generation: Create many UUIDs at once with configurable separators; download as a text file
3. Validation: Paste an existing UUID to check format and parse version, variant, and timestamp (v7)

Use Cases

• Database primary keys: Avoid collisions in distributed systems
• Frontend temporary IDs: List keys, draft form identifiers
• Logging and tracing: Assign a unique ID per request or event
• Time-ordered IDs (v7): Indexes or audit logs that benefit from roughly chronological ordering

Single UUID

1. On the Generate UUID tab, pick v4 (random) or v7 (time-ordered)
2. Choose output format: lowercase/uppercase, with or without hyphens
3. Click Generate new UUID and copy the result

Batch Generation

1. Open the Batch generate tab
2. Set count (1–1,000), separator (newline, comma, semicolon), and format options
3. Click Batch generate, then copy all or download as a text file

Validate a UUID

1. Open the Validate UUID tab
2. Paste the string (with or without hyphens)
3. Click Validate to see validity, version, variant; for v7, the embedded timestamp is shown

Invalid strings that do not match RFC 4122 are reported as invalid.

FAQ

How do I generate UUID online?

Open the Generate UUID tab, choose v4 or v7 and format options, then click generate. IDs are created locally in your browser; batch mode creates many at once. Versions follow RFC 4122 and RFC 9562.

Q: Should I use UUID v4 or v7?

Use v4 when you only need uniqueness with no ordering requirement. Use v7 when IDs should sort roughly by creation time (logs, time-series indexes). See RFC 9562 for v6–v8.

Q: Are UUIDs globally unique?

They are designed so collisions are negligible when using a proper CSPRNG. v4 relies on secure randomness. For zero-tolerance policies, still enforce a unique constraint in your database.

Q: With hyphens vs without?

The standard form is 36 characters including hyphens (8-4-4-4-12). The 32-character hex form is equivalent and common in URLs or compact storage. This tool supports both for generation and validation.

Q: How do I check if a UUID is valid?

Use the Validate UUID tab here, or verify length, hex digits, version nibble, and variant bits per RFC 4122.

Q: Can batch generation produce duplicates?

Each UUID in a batch is generated independently (random v4 or time-based v4 with random suffix). Duplicates within one batch are extremely unlikely. Deduplicate across sessions in your application if needed.

Q: Is data sent to a server?

No. Generation and validation run locally in the browser using Web Crypto where applicable.

UUID Structure

A standard UUID is 128 bits, written as xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx:

• M is the version (e.g. 4 for v4, 7 for v7)
• N encodes the variant; RFC 4122 variant uses 10 in the high bits of that nibble

v4: Random UUID

v4 uses 122 random bits (remaining bits fix version and variant). Implementations should use a cryptographically secure PRNG; this tool uses crypto.getRandomValues() as recommended on MDN.

v7: Time-Ordered UUID

v7 embeds a Unix timestamp in milliseconds in the high bits and randomness in the low bits, so new IDs tend to increase lexicographically—helpful for B-tree locality. Defined in RFC 9562.

Comparison with ULID

ULID also provides time ordering but uses Crockford Base32 (26 characters). UUID v7 stays in hex and fits existing database UUID types without conversion.

References

• RFC 4122 — UUID
• RFC 9562 — UUIDs v6–v8