Are generated UUIDs cryptographically strong?

Version 4 UUIDs here draw entropy from crypto.getRandomValues. That is appropriate for unique identifiers. It is still not a reason to use a UUID as a bearer secret without additional access controls.

Which UUID versions are supported?

This generator focuses on random v4 UUIDs. Time-based v1, name-based v3/v5, and newer versions are not produced here. Pick the version your protocol documents.

What is the chance two UUIDs collide?

With 122 random bits, accidental collision probability is negligible for ordinary application volumes. Operational bugs (copy-paste reuse, seeding mistakes) cause “duplicates” far more often than math does.

Can I use UUIDs as API tokens or passwords?

Prefer purpose-built secret generators, hashed password storage, and short-lived tokens with revocation. A UUID identifies; it does not encode authorization policy by itself.

Why are there hyphens in the string?

RFC 4122 textual representation groups hex digits 8-4-4-4-12. Many databases accept both hyphenated and compact forms—follow your schema. The underlying 128-bit value is what matters.

Is a GUID the same as a UUID?

In practice, Microsoft GUID terminology refers to the same 128-bit identifier family. Formatting and brace styles may differ in Windows tooling, but v4 randomness concepts align.

Do UUIDs leak creation time?

Version 4 UUIDs are random and do not embed timestamps. Version 1 UUIDs do embed time and node information—another reason this page sticks to v4 for general-purpose IDs.

Are UUIDs sortable by creation order?

Random v4 values are not time-ordered. If you need roughly sortable IDs, look at ULID, KSUID, or UUID versions designed for that property in your stack—not raw v4.

Where are UUIDs generated?

Only in your browser. Nothing is sent to Vastorae servers during generation.

Can databases index UUID primary keys efficiently?

Yes, but random v4 keys can fragment some B-tree indexes compared with sequential integers. Many teams still prefer UUIDs for merge-friendly distributed writes; measure for your database.

UUID Generator

Universally unique identifiers let distributed systems name records without a central ID server. This UUID generator creates version 4 UUIDs—122 bits of randomness plus fixed version and variant bits—using crypto.getRandomValues in your browser. Paste them into API clients, seed files, and database fixtures when you need unique keys quickly. UUIDs are identifiers, not authentication secrets: treat access tokens and API keys as a separate class of credential. Generation stays local, so bulk test IDs never need to round-trip through a remote service just to populate a spreadsheet.

4e39bee9-4997-40d9-accd-d100704c9681

Informational only; verify critical results independently.

How to use

Choose how many UUIDs you need for the task—one for a request ID, or a batch for fixtures.
Click generate; each value is produced with cryptographically strong browser randomness.
Copy a single UUID or the full list into your app, database seed, or configuration file.
Generate again whenever you need a fresh set; previous values are not stored by the site.
Keep the standard 8-4-4-4-12 hyphenated form unless your system documents a compact hex requirement.
Use UUIDs for correlation IDs, primary keys, and idempotency keys—not as password substitutes.
When bulk-loading, paste into a text file first so you can review duplicates visually (they should not appear).
Strip hyphens only at the boundary your API documents; do not invent formats mid-pipeline.

Examples

One UUID as an X-Request-Id header value for tracing a single API call.
Ten UUIDs as synthetic user ids in a QA spreadsheet.
One hundred UUIDs exported into a SQL seed or JSON fixtures file.
Five UUIDs as session or correlation identifiers in a load-test script.
A single UUID as a new resource name when human-readable slugs are not required.
Twenty UUIDs as stable import keys for a CSV migration batch.
Format check: version nibble is 4 (xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx) with y in 8, 9, a, or b.
Compact form: remove hyphens from 550e8400-e29b-41d4-a716-446655440000 → 550e8400e29b41d4a716446655440000 when a legacy field forbids dashes.
Compare two freshly generated UUIDs to illustrate that collisions are not expected in normal volumes.

FAQ

Are generated UUIDs cryptographically strong?: Version 4 UUIDs here draw entropy from crypto.getRandomValues. That is appropriate for unique identifiers. It is still not a reason to use a UUID as a bearer secret without additional access controls.
Which UUID versions are supported?: This generator focuses on random v4 UUIDs. Time-based v1, name-based v3/v5, and newer versions are not produced here. Pick the version your protocol documents.
What is the chance two UUIDs collide?: With 122 random bits, accidental collision probability is negligible for ordinary application volumes. Operational bugs (copy-paste reuse, seeding mistakes) cause “duplicates” far more often than math does.
Can I use UUIDs as API tokens or passwords?: Prefer purpose-built secret generators, hashed password storage, and short-lived tokens with revocation. A UUID identifies; it does not encode authorization policy by itself.
Why are there hyphens in the string?: RFC 4122 textual representation groups hex digits 8-4-4-4-12. Many databases accept both hyphenated and compact forms—follow your schema. The underlying 128-bit value is what matters.
Is a GUID the same as a UUID?: In practice, Microsoft GUID terminology refers to the same 128-bit identifier family. Formatting and brace styles may differ in Windows tooling, but v4 randomness concepts align.
Do UUIDs leak creation time?: Version 4 UUIDs are random and do not embed timestamps. Version 1 UUIDs do embed time and node information—another reason this page sticks to v4 for general-purpose IDs.
Are UUIDs sortable by creation order?: Random v4 values are not time-ordered. If you need roughly sortable IDs, look at ULID, KSUID, or UUID versions designed for that property in your stack—not raw v4.
Where are UUIDs generated?: Only in your browser. Nothing is sent to Vastorae servers during generation.
Can databases index UUID primary keys efficiently?: Yes, but random v4 keys can fragment some B-tree indexes compared with sequential integers. Many teams still prefer UUIDs for merge-friendly distributed writes; measure for your database.

Formula / Method

Draw 16 random bytes from a CSPRNG (crypto.getRandomValues). Set the version nibble to 4 (byte 6 high nibble). Set the variant bits to RFC 4122 (byte 8 high bits 10xx). Format as eight hex digits, hyphen, four, hyphen, four, hyphen, four, hyphen, twelve. Example shape: 550e8400-e29b-41d4-a716-446655440000 (illustrative). Collision probability for k generated IDs scales roughly with k² / 2¹²² for birthday-bound intuition—still tiny at everyday counts.

Assumptions & Limitations

Produces v4 only. Does not allocate from a central registry, validate uniqueness against your database, or guarantee index performance characteristics. Browser entropy quality depends on a functioning Web Crypto environment. Not a substitute for secret management, OAuth tokens, or password hashing. Compact/URN formatting variants are left to the consumer after copy.

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Last updated: 2026-07-28

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