UUID Generator
Generate UUIDs (v4) instantly — batch mode, custom formats, one-click copy
100% freeRuns in browserNo data sent to servers
0 UUIDs generated Format: standard
Click Generate to create UUIDs
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How It Works
1
Pick quantity and format
Choose how many UUIDs you need (1 to 100) and select a format — standard lowercase, uppercase, no hyphens, or with braces.
2
Click Generate
Hit the Generate button to create cryptographically random v4 UUIDs instantly in your browser. No server calls, no waiting.
3
Copy one or all
Click the copy icon next to any UUID, or use Copy All to grab the entire batch. Paste wherever you need them.
FAQ
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. It looks like 550e8400-e29b-41d4-a716-446655440000 — 32 hexadecimal digits displayed in five groups separated by hyphens. UUIDs are used to uniquely identify resources without a central authority.
What UUID version does this generate?
This tool generates version 4 (v4) UUIDs, which are based on random or pseudo-random numbers. V4 is the most commonly used version and is generated using the browser's crypto.randomUUID() API, which provides cryptographically secure random values.
Are UUIDs truly unique?
In practice, yes. A v4 UUID has 122 random bits, yielding 5.3 x 10^36 possible values. The probability of generating a duplicate is astronomically low — you would need to generate about 2.71 x 10^18 UUIDs to have a 50% chance of one collision.
What is the probability of a UUID collision?
For v4 UUIDs, the collision probability follows the birthday problem formula. Generating 1 billion UUIDs per second for 85 years gives roughly a 50% collision chance. For any realistic workload, collisions are effectively impossible.
What is the difference between UUID and GUID?
They are the same thing. UUID is the term used in the RFC 4122 standard and most programming contexts. GUID (Globally Unique Identifier) is Microsoft's terminology, used in .NET, SQL Server, and Windows COM. The format and generation methods are identical.
When should I use UUIDs vs auto-increment IDs?
Use UUIDs when you need IDs generated without a central database (distributed systems, offline-first apps, API resources). Use auto-increment IDs when you need compact, sortable, human-readable identifiers and have a single database. UUIDs are 36 characters; auto-increment IDs are much shorter.
Can I generate UUIDs in bulk?
Yes. Use the quantity selector to generate 1, 5, 10, 25, 50, or 100 UUIDs at once. Each UUID gets its own copy button, and you can use Copy All to grab the entire batch as a newline-separated list.
What formats are supported?
Four formats: Standard (lowercase with hyphens), Uppercase, No Hyphens (32 hex characters without dashes), and Braces (wrapped in curly braces, common in .NET and COM).
Is this processed locally?
Yes. See all <a href="/ai/dev">Dev Tools</a> and <a href="/ai/dev/hash">Hash Generator</a>. All UUID generation happens entirely in your browser using the Web Crypto API. No data is sent to any server. The tool works offline once the page is loaded.
What is a v4 UUID?
A v4 UUID is a UUID where 122 of the 128 bits are randomly generated. The remaining 6 bits encode the version (4) and variant (RFC 4122). The version digit appears as the 13th hex character (always "4"), and the variant appears as the 17th character (always "8", "9", "a", or "b").
Are hyphens required in UUIDs?
No. Hyphens are a display convention, not part of the underlying 128-bit value. Many databases and APIs accept UUIDs without hyphens. This tool offers a "No Hyphens" format for those use cases. When storing UUIDs, some databases like PostgreSQL have a native UUID type that handles formatting automatically.
Can I use UUIDs as database primary keys?
Yes, and it is common practice. PostgreSQL has a native uuid type. MySQL can store them as CHAR(36) or BINARY(16). The tradeoff: UUIDs are larger than integers and random v4 UUIDs cause index fragmentation. Consider UUID v7 (time-ordered) for write-heavy tables.
How long is a UUID?
A UUID is 128 bits (16 bytes) of data. In its standard string representation with hyphens, it is 36 characters long (32 hex digits + 4 hyphens). Without hyphens, it is 32 characters.
Is there a UUID v7?
Yes. UUID v7 (defined in RFC 9562, finalized 2024) encodes a Unix timestamp in the first 48 bits, making UUIDs naturally sortable by creation time. This solves the index fragmentation problem of random v4 UUIDs. V7 is gaining adoption but v4 remains the most widely used version.
What other Coda One developer tools are there?
Coda One provides 15+ free developer tools including JSON Formatter, Base64 Encoder, Hash Generator, Regex Tester, Timestamp Converter, JWT Decoder, Case Converter, and more. All tools run in your browser with no signup required.
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Coda One's UUID Generator creates cryptographically random v4 UUIDs using the Web Crypto API. Generate single or batch UUIDs (up to 100 at once) in four formats: standard lowercase, uppercase, no hyphens, or with braces. Every UUID is generated locally in your browser — no data is sent to any server. One-click copy for individual UUIDs or copy all at once. Free, no signup, no limits.