UUID Generator
Generate random, unique UUID v4 identifiers instantly. Bulk generation supported. Uses cryptographic randomness — runs entirely in your browser.
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A UUID (Universally Unique Identifier) is a 128-bit value represented as 32 hexadecimal digits grouped in the familiar 8-4-4-4-12 format — for example, 550e8400-e29b-41d4-a716-446655440000. UUID v4, the most widely used variant, is generated entirely from random bits, making collision practically impossible even when millions of identifiers are created per second across distributed systems. Yanapex's UUID Generator produces v4 identifiers using the Web Crypto API's crypto.getRandomValues method, which draws from your operating system's cryptographically secure entropy source. This ensures that every UUID you generate meets the randomness standards required for security-sensitive applications such as session tokens, database primary keys, and distributed transaction IDs.
UUID v1 is time-based and encodes the current timestamp together with a node identifier, making it monotonically increasing and useful for time-ordered records. UUID v5 is name-based, producing deterministic output from a namespace and an input string using SHA-1 hashing — ideal for generating the same UUID from the same logical resource URI every time.
Choose a UUID version — v4 (random), v1 (time-based), or v5 (name-based with namespace input).
Set the quantity if you need bulk output, then click Generate.
Copy one or all UUIDs with a single click and paste them directly into your code, database, or API call.
What Is a UUID?
A UUID is a standardized identifier defined in RFC 4122 that is guaranteed to be unique across all devices and all time without requiring a central authority to coordinate assignment. The 128-bit space gives approximately 5.3 × 10³⁸ possible values for version 4, making the probability of a collision between two randomly generated UUIDs astronomically low — lower than one in a trillion even after generating a billion UUIDs per second for a hundred years. This property makes UUIDs the go-to choice for primary keys in distributed databases, microservice correlation IDs, and client-generated identifiers in offline-first applications.
How to Use the UUID Generator
Select the UUID version you need from the version selector — v4 for random identifiers, v1 for time-ordered identifiers, or v5 for a deterministic name-based UUID (enter a namespace and name). Enter the number of UUIDs to generate in the quantity field; you can generate several hundred at once for bulk operations. Click Generate and the results appear instantly in the output panel. Use the Copy button to copy a single UUID, or copy all results at once with Copy All. No data is sent to any server — everything runs locally in your browser.
Why UUIDs Are Essential in Modern Development
UUIDs eliminate the coordination overhead that integer sequences require. In a monolithic application backed by a single database, auto-incrementing IDs work fine. But in a microservices architecture, a mobile app that must create records while offline, or a distributed system with multiple write nodes, you need a way to mint unique identifiers without asking a central service first. UUID v4 lets any client — a mobile device, a browser, a serverless function — generate a globally unique key on its own, then safely merge that record into any database or message queue without risk of conflict.
Common Use Cases
Common use cases include: primary keys in PostgreSQL, MySQL, or SQLite tables in distributed setups; document IDs in MongoDB, Firestore, or DynamoDB; idempotency keys in payment APIs such as Stripe to prevent duplicate charges; correlation IDs attached to HTTP request headers for distributed tracing; file names for user-uploaded assets stored in S3 or cloud storage to prevent overwrites; session identifiers in authentication tokens; and resource URIs in REST APIs where the client specifies the resource ID before creation.
Frequently asked questions
Is UUID v4 truly unique?
In practice, yes. UUID v4 has a 128-bit random space of roughly 5.3 × 10³⁸ possible values. The probability of generating a duplicate even after creating one billion UUIDs per second for a century is vanishingly small — far below the risk of hardware failure or software bugs. For all practical purposes, each UUID v4 you generate is globally unique.
Does this tool send my UUIDs to a server?
No. All UUID generation happens locally in your browser using the Web Crypto API. Nothing is transmitted over the network, so your identifiers remain completely private.
What is the difference between UUID v1, v4, and v5?
v1 encodes the current timestamp and a node identifier, making it time-sortable but potentially privacy-sensitive. v4 is purely random with no embedded metadata. v5 is deterministic — it hashes a namespace plus a name with SHA-1 to always produce the same UUID for the same input.
Can I use UUIDs as database primary keys?
Yes, and it is a common pattern. UUID primary keys let client applications create records offline and merge them later without ID conflicts. The trade-off is index fragmentation on some databases; for write-heavy tables consider UUID v7 (ordered by time) or storing UUIDs as binary(16) rather than varchar(36).
What format is a UUID in?
A UUID is 32 hexadecimal characters split into five groups by hyphens in the 8-4-4-4-12 pattern, for example 550e8400-e29b-41d4-a716-446655440000. The total is 128 bits. The version and variant bits are encoded in specific character positions within the identifier.