Free UUID / GUID Generator Online — Generate UUIDs Instantly

Free UUID / GUID Generator Online — Generate UUIDs Instantly in Your Browser

Generate UUIDs (Universally Unique Identifiers) — also called GUIDs (Globally Unique Identifiers) — instantly in your browser. No server call, no signup, no data sent anywhere. Every UUID is generated client-side using JavaScript's cryptographic random number APIs.

What is a UUID?

A UUID is a 128-bit identifier standardized in RFC 9562 (which superseded the original RFC 4122 in May 2024). Written in its canonical form it looks like 550e8400-e29b-41d4-a716-446655440000 — 32 hexadecimal digits arranged in five groups separated by hyphens. The probability of generating a duplicate UUID is astronomically small, making UUIDs ideal for primary keys, session IDs, file names, distributed system identifiers, and any context where global uniqueness is needed without central coordination.

UUID v4 vs UUID v1 — which should I use?

UUID v4 (random) is the right choice for almost every use case. The 122 random bits mean uniqueness is virtually guaranteed, and because the values are not predictable or time-ordered, they work safely as public-facing identifiers. v4 is the industry default for database primary keys, API tokens, and file identifiers.

UUID v1 (timestamp-based) encodes the current timestamp in its first fields, making UUIDs generated close together sort roughly in chronological order. This is useful in databases that benefit from time-ordered inserts (e.g., Cassandra), but be aware that v1 UUIDs encode timing information — a minor privacy consideration for public-facing use.

Aspect	UUID v4 (Random)	UUID v1 (Timestamp)
Basis	122 random bits	Current timestamp + node ID
Sortable by creation time	No	Yes (roughly)
Predictability	Not predictable	Encodes timing information
Best for	Primary keys, API tokens, public-facing IDs	Time-ordered database inserts (e.g., Cassandra)
Privacy consideration	None	Reveals approximate generation time

UUID vs GUID — is there a difference?

Not in practice. GUID is Microsoft's term for the same 128-bit identifier format. The underlying structure is identical; the names are used interchangeably. If you are generating identifiers for a .NET, COM, or Windows API context, "GUID" is the conventional term. Everywhere else, "UUID" is standard.

Bulk UUID generation

Set the Quantity field to any number up to 1,000 and click Generate. You can output the results as a plain line-by-line list, a comma-separated list for direct use in SQL IN clauses or spreadsheets, or as a JSON array ready to paste into configuration files or API requests.

Uppercase, lowercase, and hyphens

The canonical UUID format uses lowercase letters with hyphens (e.g. 550e8400-e29b-41d4-a716-446655440000), but many systems accept uppercase or omit hyphens entirely. Toggle Case and Hyphens as needed — these options reformat the existing batch instantly without regenerating new UUIDs.

Frequently Asked Questions About UUID Generator

Are the generated UUIDs truly unique?

For v4 UUIDs the entropy is 122 random bits. The odds of two randomly generated v4 UUIDs colliding are approximately 1 in 5.3 × 10³⁶ — effectively impossible. This generator uses crypto.randomUUID() when available in your browser, which is a cryptographically secure source of randomness.

Are my UUIDs saved or sent to a server?

No. Every UUID is generated entirely in your browser using JavaScript. Nothing is sent to any server. You can even use this tool offline.

What is the difference between UUID v4 and v1?

UUID v4 uses 122 random bits and has no predictable structure. UUID v1 encodes the current timestamp in the first fields so UUIDs generated around the same time will sort similarly. Use v4 for general purpose IDs and v1 when time-ordered generation is a requirement.

Can I use a UUID without hyphens?

Yes. Toggle "Without hyphens" to produce a compact 32-character hex string (e.g. 550e8400e29b41d4a716446655440000). This format is accepted by most databases and APIs and is simply the canonical UUID with the separator characters removed.

How do I generate a UUID in bulk for a SQL IN clause?

Set your desired count, click Generate, then switch the Output Format to "Comma separated". Copy the result and wrap it in parentheses for use as a SQL IN list. Alternatively, select "JSON array" to get a ready-to-use JSON structure.

What does UUID v1 use for the node identifier?

In a browser environment there is no access to your MAC address. This generator creates a random 48-bit node identifier once per page session and reuses it for all v1 UUIDs generated in that session, which is the RFC 4122-compliant approach when a hardware address is unavailable.

What is the difference between UUID and GUID?

There is no practical difference. GUID is Microsoft's term for the same 128-bit identifier format used in UUID. The underlying structure is identical.

UUID / GUID Generator

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