UUID v4 Generator

Generate RFC 4122 UUID v4 identifiers — single or in bulk, uppercase, no-hyphen or URN format. Validate any UUID version and variant. 100% client-side.

Count Format

Generated

Validate UUID

How it works

Single-click generates a cryptographically random UUID v4 using the browser's crypto.randomUUID() (modern browsers) or a crypto.getRandomValues() fallback.
Batch mode produces up to 1000 UUIDs at once for test data, migration scripts, or seed files.
The validator accepts any UUID string and reports the version (v1 timestamp-based, v4 random, v7 sortable) and variant (RFC 4122 vs Microsoft vs NCS backward compatibility).

About UUID v4

A UUID v4 is 122 bits of randomness formatted as 36 characters with hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The leading 4 identifies the version; the y nibble encodes the variant. Since every browser, every runtime, and every operating system can generate these independently without a central registry, UUIDs are the standard way to assign globally unique identifiers to database rows, API keys, correlation IDs, event streams, and ephemeral tokens.

v4 and v7 solve different problems

A v4 UUID is 122 random bits with no structure. It is the right default for anything that must be unpredictable or globally unique without coordination — object identifiers, token values, anything where two systems might generate the same id.

A v7 UUID leads with a millisecond timestamp followed by random bits. That makes ids sortable by creation time, which turns an expensive "find by created_at and filter by id" query into an index range scan on the primary key. Use v7 for database primary keys where insert order matters.

If you are using v4 and find index fragmentation on large tables, switching to v7 is usually the fix.

Version and variant bits

The version nibble and the two variant bits are fixed by RFC 9562; that is why not every 128-bit value is a valid UUID. The validator on this page reports the version and variant, and will flag a UUID that is well-formed but not RFC-compliant.

Next steps

UUID v7 Generator— time-ordered alternative

Frequently Asked Questions

How do I generate a UUID v7?

Click Generate to create a new UUID v7. You can generate a batch of up to 100 at once. Each UUID contains a timestamp component encoding the creation time, allowing you to sort records by creation order.

Can I decode a UUID v7 to find when it was created?

Yes. Paste any UUID v7 into the decoder and it extracts and displays the embedded timestamp, showing the exact creation date and time in UTC.

Is my data sent to a server?

No. Every tool on jsonversal runs entirely in your browser using the Web Crypto API, File API, and Clipboard API. Nothing is ever uploaded — not even the JSON you paste in.

Do I need an account or API key?

No signup, no email, no API key. All tools are free to use with no signup required.

Can I use these tools offline?

Yes. Once the page loads, all tools work offline. There are no external API calls or CDN dependencies at runtime.

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Your data never leaves your device

All processing happens in your browser. No uploads, no tracking, no servers. Your API keys, configs, and private payloads stay private — 100% client-side.