UUID Generator — Generate UUID v4 Online

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit number represented as a 32-character hexadecimal string in the format `xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`. UUID v4 is generated using random or pseudo-random numbers. There are 5.3 × 10³⁶ possible UUIDs — making collisions astronomically unlikely.

Why Use UUIDs?

Sequential integer IDs expose information (how many records exist, the order they were created). They also create challenges in distributed systems where multiple nodes insert records simultaneously. UUIDs solve both: they're opaque and can be generated independently on any client without coordination.

Two Tabs: Generator and Inspect

The Generator tab creates UUID v4 values in bulk using the browser's native crypto.randomUUID() — cryptographically secure and RFC 4122 compliant. The Inspect tab accepts an existing UUID and tells you its version (v1–v5), variant, and whether the format is valid — useful for debugging IDs that came from an external system or an unfamiliar library.

Key Benefits

• Generate single or bulk UUIDs (up to 100 at once)
• RFC 4122 compliant UUID v4
• Uses browser's native crypto.randomUUID()
• Inspect tab validates any UUID and shows version and variant
• Copy individually or all at once
• Works with tool chaining — paste a UUID from another tool directly

How to Use UUID Generator

1. Generator tab: click Generate for one UUID, or set a count for bulk
2. Copy individual UUIDs or click Copy All
3. Paste into your code, database, or config
4. Inspect tab: paste any UUID string
5. The tool shows version, variant, and whether the format is valid

Example Use Case

Seeding a database with test records. Each record needs a unique ID before insert (so foreign keys can be set up ahead of time). Generate 50 UUIDs at once, copy all, paste into the seed script. Later, use the Inspect tab to verify that IDs returned by an external API are valid v4 UUIDs.

Tips

• UUID v4 is the most common — use it unless you have a specific reason for v1 or v5
• UUIDs are case-insensitive — both uppercase and lowercase are valid
• Storing UUIDs in databases: use a UUID type column or CHAR(36)
• UUID v1 includes timestamp and MAC address — UUID v4 is preferable for privacy
• Use the Inspect tab to debug IDs that fail validation in your backend — it shows exactly why