Free UUID Generator (v4)
Updated September 2026
Generate random v4 UUIDs instantly. Bulk generate up to 20 at once, copy individually or all at once — free, runs entirely in your browser.
Verified Capabilities
Generates cryptographically random v4 UUIDs using the browser's crypto.getRandomValues API.
Generate 1 to 20 UUIDs at once with a single click.
Each UUID has its own Copy button, plus a Copy All button for the full list.
Only v4 (random) UUIDs in lowercase are supported — there's no version selector or case toggle.
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are designed to be globally unique without a central coordinator — two independently generated UUIDs will almost never collide, even across billions of records.
Why v4?
This tool generates UUID v4 — the random variant, and the most widely used. Unlike v1 (which embeds a timestamp and MAC address) or v5 (a deterministic hash of a namespace and name), v4 needs no extra inputs and reveals no information about when or where it was created, making it the safe default for most applications.
When to use UUIDs
UUIDs are used as primary keys in distributed databases, session tokens, file identifiers, API resource IDs, and anywhere a unique identifier must be generated without coordination between servers.
How the UUID Generator works
Enter how many UUIDs you want (1 to 20).
Click Generate UUIDs to produce random v4 UUIDs instantly.
Copy an individual UUID with its Copy button, or click Copy All to copy the whole list.
Click Generate UUIDs again anytime to replace the list with a fresh set.
Tips & tricks
- Need more than 20 at once? Generate in batches and combine the lists — 20 is the per-click limit.
- v4 UUIDs are random, not sequential — don't rely on them for insertion order.
- Store UUIDs as your database's native UUID/binary type when available, not as plain text, for better index performance.
- Copy All pulls every UUID currently on screen, newline-separated — handy for pasting into a spreadsheet or seed script.
Frequently Asked Questions
What is a UUID and when should I use one?
UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 8-4-4-4-12 hexadecimal characters (e.g. 550e8400-e29b-41d4-a716-446655440000). Use UUIDs as database primary keys, API resource IDs, and session tokens where uniqueness without central coordination is needed.
Why does this tool only generate v4 (random) UUIDs?
v4 is the most widely used UUID version and needs no extra inputs like v1's timestamp/MAC address or v5's namespace — it's the safe general-purpose default, which is why this tool focuses on it. v4 also reveals no information about when or where it was created.
Are generated UUIDs truly unique?
UUID v4 has 2^122 possible values (≈5.3 × 10^36). The probability of two randomly generated UUID v4s colliding is astronomically small — generating 1 billion UUIDs per second for 100 years would have a ~50% chance of just one collision.
Can I generate UUIDs in uppercase?
This tool generates lowercase UUIDs, the standard and most common format. Uppercase and lowercase are equally valid — if you need uppercase, run the output through your editor's case-conversion function.
Is it safe to use UUIDs as database primary keys?
Yes — v4 UUIDs are commonly used as primary keys, especially in distributed systems where auto-incrementing IDs would need central coordination. The tradeoff: UUIDs take more storage than integers and are unordered, which can affect index performance on very large tables.
Is my data safe when using the UUID Generator?
Completely safe. The UUID Generator processes everything locally in your browser. No input data, results, or usage information is ever transmitted to or stored on any server.
Can I use the UUID Generator output in commercial projects?
Yes. The UUID Generator is a utility tool and its output carries no licensing restrictions. You are free to use results in any project, commercial or personal.
Does the UUID Generator follow official standards?
Yes. The UUID Generator is built to comply with the relevant industry standard or specification for this utility type. If you encounter an unexpected result, verify your input against the specification — edge cases outside the standard may produce undefined behaviour.
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