UUID Generator (v4)
Generate cryptographically random UUID v4 identifiers — single or in bulk up to 1000. Configurable hyphens, uppercase, and brace formats.
About this tool
A UUID (Universally Unique Identifier) is a 128-bit value used as a primary key, request ID, or any other identifier where you need uniqueness without coordinating with a central authority. v4 is the random variant — almost all of the bits are unpredictable random data, with 6 reserved to indicate the version and variant. The collision probability is negligible for any practical workload.
WRRK's generator uses crypto.randomUUID() (with a crypto.getRandomValues() fallback for older browsers), which calls into the operating system's cryptographically secure random source. Bulk mode generates up to 1000 IDs in a single click, perfect for seeding test data, migrations, fixture files, or load tests. Format toggles cover the four common presentations: hyphenated lowercase (canonical), no-hyphens (compact MySQL CHAR(32)), uppercase, or wrapped in braces (.NET style).
How to generate UUIDs (5 steps)
- Pick a count. Choose how many UUIDs to generate (1 – 1000). Default is 10.
- Pick formatting. Toggle hyphens, uppercase letters, or curly braces depending on what your downstream system expects.
- Click Generate. A fresh batch is generated using crypto.randomUUID() — the same secure source used by TLS.
- Copy individual or all. Click Copy next to a single UUID, or 'Copy all' for a newline-separated list ready to paste into seed scripts.
- Download as .txt. Click 'Download .txt' to save the batch to a file — handy for migrations or fixtures.
Use cases
- Generating primary keys for new database rows
- Producing trace / request IDs for distributed logging
- Seeding test data and fixture files in bulk
- Idempotency keys for HTTP POST and Stripe-style APIs
- Naming files, S3 objects, or event IDs uniquely
- Generating session, invite, or magic-link tokens
- Webhook delivery IDs for retry de-duplication
Frequently asked questions
+−What is a UUID v4?
A UUID v4 is a 128-bit identifier whose value is generated entirely from cryptographically random bytes (with 6 bits reserved to mark version 4 and the variant). It looks like xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where the 4 marks the version. Collision probability is astronomically small — 1 in 2^122 for any two random UUIDs.
+−Are these UUIDs cryptographically secure?
Yes. The tool uses crypto.randomUUID() (or crypto.getRandomValues() as a fallback), which calls into the operating system's secure random source. Same source used by TLS, password generation, and session tokens.
+−Should I use UUID v4 or v7 for database keys?
v4 is fully random — great for distribution and security but bad for B-tree index locality. v7 (time-ordered) is better for high-write databases because new IDs cluster together. This tool generates v4 because it's still the most widely supported and the right choice for most APIs.
+−Can I generate UUIDs in bulk?
Yes. Set the count up to 1000 and click Generate. Use 'Copy all' for a newline-separated list, or 'Download .txt' to save them as a file. Useful for seeding test data, migrations, or load test fixtures.
+−Are UUIDs truly unique?
Effectively yes. UUID v4 has 122 random bits — you'd need to generate 1 billion UUIDs per second for 86 years to hit a 50% chance of one collision. For any practical workload, treat them as unique without coordination.
+−Do hyphens, braces, and case matter?
No — UUIDs are case-insensitive and the hyphens are visual sugar. Most languages, databases, and APIs accept any of these forms. Pick whichever your downstream system prefers (Postgres uuid is fine with both, .NET often uses braces, MySQL CHAR(32) wants no hyphens).
+−Are UUIDs sent to a server?
No. Generation runs entirely in your browser via the WebCrypto API. UUIDs you generate here are never logged, transmitted, or stored.