What is UUID Generator?
Free UUID generator. Generate version 1, 4, and 7 UUIDs in bulk — individually or as a JSON / newline list. Runs 100% in your browser. No signup, no server.
UUID Gen runs entirely in your browser using Web Crypto API. Your data never leaves your device.
Free UUID Generator
Generate unique identifiers instantly — no server, no account, no tracking. Choose UUID v4 (random), v1 (timestamp-based), or v7 (sortable timestamp + random). Generate up to 100 at once and copy them individually, as a newline-separated list, or as a JSON array.
Choose a version and click Generate.
Generated in your browser using crypto.getRandomValues — nothing is sent to any server.
Frequently Asked Questions
What is a UUID?+
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. They are formatted as 32 hexadecimal digits separated by hyphens, e.g. 550e8400-e29b-41d4-a716-446655440000. Also called a GUID (Globally Unique Identifier) in Microsoft contexts.
What is the difference between UUID v1, v4, and v7?+
UUID v1 encodes the current timestamp and a node identifier (MAC address or random bytes), making it time-sortable but potentially leaking timing information. UUID v4 is entirely random — the most widely used version for general-purpose unique IDs. UUID v7 (a newer draft standard) combines a millisecond-precision Unix timestamp with random bits, making it both random and naturally time-sortable — ideal for database primary keys.
Are the generated UUIDs truly unique?+
UUID v4 uses crypto.getRandomValues() — the same cryptographically secure source used by TLS and password managers. The probability of generating two identical v4 UUIDs is astronomically small: roughly 1 in 5.3 × 10³⁶. For all practical purposes, every UUID you generate here is globally unique.
Is it safe to use browser-generated UUIDs in production?+
Yes. Browsers expose the Web Crypto API (crypto.getRandomValues) which is a CSPRNG — a cryptographically secure pseudo-random number generator. This is exactly what server-side UUID libraries like uuid or crypto.randomUUID() use under the hood. The output is indistinguishable in quality.
What is a GUID? Is it the same as a UUID?+
GUID (Globally Unique Identifier) is Microsoft's term for a UUID. They use the same format and the same generation algorithms. A GUID generated here is fully compatible with .NET, SQL Server, Azure, and any other system that expects a GUID.
Can I use these UUIDs as database primary keys?+
Yes — but if you're inserting at high volume, prefer UUID v7. Its timestamp prefix keeps rows in insertion order, which significantly reduces B-tree fragmentation in databases like PostgreSQL and MySQL compared to v4's fully random layout.
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UUID and GUID Generation — Everything You Need to Know
A UUID (Universally Unique Identifier) is a 128-bit label used to identify information in computer systems without requiring a central registration authority. The format is always 32 hexadecimal characters split into five groups: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Because the space of possible UUIDs is so large (2¹²⁸, or about 3.4 × 10³⁸), the probability of two randomly generated UUIDs colliding is effectively zero.
UUID v4 — Random (the Default)
UUID v4 uses 122 bits of cryptographically random data. This tool generates v4 UUIDs using crypto.getRandomValues() — the Web Crypto API — which is a CSPRNG (cryptographically secure pseudo-random number generator). This is the same source used by TLS, web authentication, and server-side UUID libraries. The output is indistinguishable in quality from a UUID generated by a backend service.
Use v4 for: user IDs, session tokens, content IDs, order numbers, or any identifier where uniqueness is required but ordering is not.
UUID v1 — Timestamp-Based
UUID v1 encodes the current timestamp (as 100-nanosecond intervals since 15 October 1582) plus a clock sequence and node identifier. The result is time-sortable but the timestamp can be extracted from it — a privacy consideration in some contexts. This tool generates v1 UUIDs with a random node component rather than a real MAC address, so no hardware information is embedded.
Use v1 when: you need to reconstruct the approximate creation time from the ID itself, or for legacy systems that require v1.
UUID v7 — Sortable Timestamp + Random (Recommended for Databases)
UUID v7 is a newer draft RFC standard that combines a 48-bit millisecond-precision Unix timestamp with random bits. The timestamp prefix means UUIDs generated sequentially are also lexicographically ordered — critical for database performance. When you use v4 UUIDs as primary keys in PostgreSQL or MySQL, random insertions fragment the B-tree index. v7 inserts in time order, dramatically reducing fragmentation and improving write throughput at scale.
Use v7 for: database primary keys, event log IDs, or any scenario where both uniqueness and natural ordering matter.
UUID vs. GUID — What's the Difference?
Nothing meaningful. GUID is Microsoft's name for the same concept — used throughout the .NET ecosystem, SQL Server, Azure, and the Windows registry. GUIDs and UUIDs use the same format and the same generation algorithms. A UUID generated here can be used anywhere a GUID is expected, and vice versa. Some Windows tooling displays GUIDs in braces ({550e8400-...}) — that's a formatting convention, not a different standard.
How to Use Generated UUIDs in Your Code
Copy a single UUID with the inline Copy button, or use "Copy All" to get a newline-separated list suitable for pasting into a text file or spreadsheet. "Copy as JSON" outputs a proper JSON array — paste it directly into a test fixture, seed file, or configuration object. The UPPERCASE toggle is a cosmetic option; both cases represent the same UUID value.