UUID Generator
Generate cryptographically secure UUID v4 identifiers. Single or bulk generation up to 100 at a time. Copy or download instantly.
UUID Generator
Generate cryptographically secure UUID v4 identifiers instantly. Generate one or up to 100 at a time, copy or download the list. Everything runs in your browser — no data leaves your device.
Generator Settings
No UUIDs yet
Set the count above and click Generate to create UUID v4 identifiers.
What is a UUID?
A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit label standardised by RFC 4122. It is represented as 32 hexadecimal digits grouped into five sections separated by hyphens:
550e8400-e29b-41d4-a716-446655440000The design goal of UUIDs is that they can be generated independently — across different machines, at any point in time — with a collision probability so astronomically low that it is considered practically zero. This makes them ideal as database primary keys, session identifiers, and distributed system correlation IDs without requiring central coordination.
Why version 4?
There are eight UUID versions defined in RFC 9562. Version 4 is by far the most widely used because it is fully random: 122 of the 128 bits are generated by a cryptographically secure random number generator (the remaining 6 bits encode the version and variant). This tool uses the browser's built-in crypto.randomUUID() API, which is seeded by the operating system's entropy source — the same source used for TLS keys.
| Version | Basis | Typical use |
|---|---|---|
| v1 | Timestamp + MAC address | Legacy systems, time-ordered |
| v3 | MD5 hash of namespace + name | Deterministic IDs (deprecated) |
| v4 | Random (CSPRNG) | General-purpose unique IDs ✅ |
| v5 | SHA-1 hash of namespace + name | Deterministic IDs |
| v7 | Unix timestamp + random | Time-sortable DB primary keys |
How to Generate UUIDs Online
- 1
Set the count
Enter how many UUIDs you need in the "How many?" field. You can generate between 1 and 100 UUIDs per click.
- 2
Choose a case style
Select "lowercase" (default, e.g. 550e8400-…) or "UPPERCASE" (e.g. 550E8400-…). Both representations are valid RFC 4122 UUIDs — the choice is purely cosmetic.
- 3
Click "Generate"
Your UUIDs appear instantly in the output panel. Hover any row to reveal its individual copy button, or use the toolbar buttons to copy or download the entire list.
- 4
Append, copy, or download
Use "Append" to add more UUIDs to the list without clearing it. "Copy all" puts every UUID on the clipboard separated by newlines. "Download .txt" saves one UUID per line to a file.
Frequently Asked Questions
Are the UUIDs truly unique?▼
UUID v4 uses 122 bits of cryptographically secure randomness. The probability of generating two identical UUIDs is approximately 1 in 5.3 × 10³⁶ — effectively zero for all practical purposes, even at massive scale.
Is it safe to use UUIDs as database primary keys?▼
Yes, and it is a common pattern. UUIDs guarantee uniqueness across distributed systems without a central sequence generator. The main trade-off is index size (16 bytes vs 4–8 bytes for integers). UUID v7 (time-sortable) is often preferred for new projects due to better index locality.
What is the difference between UUID and GUID?▼
They are the same thing. UUID is the IETF term (RFC 4122); GUID (Globally Unique Identifier) is Microsoft's term for the same concept as used in COM/OLE and Windows APIs. The format and structure are identical.
Is my generated UUID sent to your servers?▼
No. All UUIDs are generated in your browser using the Web Crypto API (crypto.randomUUID()). Nothing is sent to our servers.
Why use crypto.randomUUID() instead of Math.random()?▼
Math.random() is not cryptographically secure — its output can potentially be predicted given enough samples. crypto.randomUUID() uses the operating system's entropy source (the same source used for TLS certificates), making the output unpredictable and safe for security-sensitive use cases.
Can I use these UUIDs in production?▼
Yes. They are standard RFC 4122 compliant UUID v4 identifiers generated with a cryptographically secure source, identical to what server-side libraries like uuid (Node.js), java.util.UUID (Java), or uuid.uuid4() (Python) produce.
Frequently Asked Questions
Are the UUIDs truly unique?
UUID v4 uses 122 bits of cryptographically secure randomness. The probability of generating two identical UUIDs is approximately 1 in 5.3 × 10³⁶ — effectively zero for all practical purposes.
Is it safe to use UUIDs as database primary keys?
Yes. UUIDs guarantee uniqueness across distributed systems without a central sequence generator. UUID v7 is preferred for new projects due to better time-sortable index locality.
What is the difference between UUID and GUID?
They are the same thing. UUID is the IETF term (RFC 4122); GUID is Microsoft's term used in COM/OLE and Windows APIs. Format and structure are identical.
Is my generated UUID sent to your servers?
No. All UUIDs are generated locally in your browser using the Web Crypto API (crypto.randomUUID()). Nothing is sent to our servers.
Why use crypto.randomUUID() instead of Math.random()?
Math.random() is not cryptographically secure and its output can be predicted. crypto.randomUUID() uses the OS entropy source — the same source used for TLS certificates.
Can I use these UUIDs in production?
Yes. They are standard RFC 4122 compliant UUID v4 identifiers, identical in quality to those from server-side libraries like uuid (Node.js) or uuid.uuid4() (Python).