UUID Generator
CryptoFree online UUID v4 & GUID generator — cryptographically secure, runs locally in your browser. Create random unique IDs for database keys, API tokens, and sessions in one click. No signup, no upload.
V4 Random (RFC 4122) · 0 generated
About UUID Generator
A UUID (Universally Unique Identifier) is a 128-bit standardized identifier, commonly written as 32 hexadecimal characters like `f47ac10b-58cc-4372-a567-0e02b2c3d479`. This tool generates RFC 4122 compliant UUID v4 values using the browser's `crypto.randomUUID()` API, which relies on cryptographically strong random number generation. UUID v4 uses 122 random bits and 6 fixed version/variant bits, yielding approximately 5.3 × 10³⁶ possible values — effectively collision-proof for practical use. All generation happens locally in your browser with no server upload, so your data stays private. Tip: Bookmark this tool for quick access whenever you need to generate keys or hashes. All processing happens locally in your browser — no data upload, so it is safe to use with sensitive material.
How to Use
- Open the UUID Generator page
- Select the number of UUIDs to generate (1-1000)
- Click the Generate button or customize options (uppercase, hyphens, braces)
- Click the copy button next to any UUID or 'Copy All' to copy all results
Use Cases
- Database primary keys — Replace auto-increment IDs in distributed systems to avoid key collisions across shards or merge writes.
- API request IDs — Tag each HTTP request with a unique marker for logging, tracing, and distributed correlation.
- Frontend list keys — Assign keys to Vue/React list items that lack a stable ID, preventing unnecessary re-renders.
- File naming — Avoid name collisions during batch uploads or caching — UUID-named files virtually never clash.
- Session tokens — Combined with a signature, build unguessable session IDs or one-time tokens.
- Correlation identifiers — Assign unique IDs to log entries, trace spans, or events across microservices to correlate distributed activity.
- Database replication — Use UUIDs as primary keys in multi-master or offline-first databases to avoid conflicts when merging writes from different nodes.
FAQ
Can UUID v4 collide?
In theory yes, but the probability is negligible. UUID v4 has 122 random bits — generating 10 billion UUIDs gives roughly 50% chance of one collision. Treat it as never colliding in practice.
Are UUID and GUID the same?
Yes. GUID is Microsoft's name for UUID; the formats are identical and interchangeable.
Why does my UUID always start the 13th character with 4?
That digit encodes the UUID version, fixed to 4 for v4. If you need time-sortable IDs, try our ULID generator.
Is UUID safe to use as a secret key?
v4 was not designed for cryptography, but 122 bits of entropy exceeds typical session tokens. For higher security, use our Token Generator instead.
How can it generate UUIDs without a server?
The browser provides crypto.getRandomValues(), a cryptographically reviewed secure random source — equivalent in quality to a server's /dev/urandom.
Any browser compatibility requirements?
This tool works in all modern browsers (Chrome, Firefox, Edge, Safari). No plugins or extensions required.
Can I use it offline?
After initial load, most features work offline. The core logic runs entirely in your browser with no network dependency.
Comments
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