UUID v4 is a 128-bit identifier generated using cryptographic randomness. The format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is a random hex digit, 4 indicates version 4, and y is one of 8, 9, a, or b. The probability of collision is astronomically low.

🆔 Utils

UUID / GUID Bulk Generator

Generate up to 1000 random UUIDs (v4) instantly using the browser's native crypto.randomUUID(). Choose your output format — plain list, JSON array, or SQL INSERT values.

📖 How to Use This Tool

▼

Set the quantity (1 to 1000 UUIDs at once)

Choose output format: list, JSON array or SQL VALUES

Click Generate — uses crypto.randomUUID() for true randomness

Click Copy to copy all generated UUIDs

📝 Examples

Single UUID

Input: Quantity: 1

Output: 550e8400-e29b-41d4-a716-446655440000

Bulk for SQL

Input: Quantity: 5, Format: SQL

Output: INSERT INTO table VALUES ('uuid1'),('uuid2')...

Count:

Format:

With braces {}

1 5 10 25 100 500

Output — 10 UUIDs

Randomness: UUIDs are generated using crypto.randomUUID() which uses a cryptographically strong random number generator. No data is sent to any server.

Quick Overview

A UUID (Universally Unique Identifier) generator creates 128-bit identifiers that are unique across space and time without requiring a central coordination authority. UUIDs are a foundational primitive in distributed systems — they allow independent services, databases, and clients to create identifiers for new records without needing to contact a central ID-issuing service, eliminating a common bottleneck and single point of failure in high-throughput architectures.

UUID v4 generates identifiers using cryptographic randomness, while UUID v5 generates deterministic identifiers by hashing a namespace and a name with SHA-1. Both versions produce identifiers in the canonical format xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx where M encodes the version and N encodes the variant. The 122 bits of randomness in a v4 UUID means the probability of generating a collision is astronomically small — with 1 trillion UUIDs generated per second, it would take 86 years before the probability of a single collision reached 50%.

Technical Details

UUID v4 generation uses the browser's native crypto.randomUUID() API, which is backed by the operating system's cryptographically secure pseudorandom number generator (CSPRNG) — the same entropy source used for TLS key generation. This ensures that each UUID is statistically unique and unpredictable. UUID v5 is generated by computing the SHA-1 hash of a namespace UUID concatenated with the name string, then formatting the first 128 bits of the hash output according to the UUID v5 layout defined in RFC 9562, setting the version bits to 5 and the variant bits to the RFC 4122 variant. Bulk generation runs in a tight loop calling crypto.randomUUID() repeatedly, with all results assembled client-side.

Common Use Cases

Generating database primary keys: Use UUID v4 to create primary keys for new database records without a database round-trip, enabling client-side record creation and offline-first architectures with PostgreSQL's uuid type or MongoDB ObjectIDs.
Creating idempotency keys for API requests: Attach a fresh UUID v4 to each payment, order, or mutation request so that servers can safely deduplicate retried requests without double-processing.
Assigning correlation IDs for distributed tracing: Generate a UUID at the entry point of a request and propagate it through all downstream service calls via headers like X-Correlation-ID or X-Request-ID to stitch together distributed traces in Jaeger, Zipkin, or Datadog APM.
Generating stable entity identifiers with UUID v5: Use UUID v5 to derive a consistent, reproducible UUID for a known entity — for example, generating the same UUID every time for a given product SKU or URL, enabling idempotent import pipelines without storing a lookup table.

UUID vs. Alternative Identifier Schemes

UUIDs aren't the only option for distributed ID generation. Snowflake-style IDs (popularized by Twitter, also used by Discord and Instagram) pack a timestamp, machine ID, and sequence counter into a 64-bit integer instead of 128 bits. The key advantage is that Snowflake IDs are roughly sortable by creation time and far smaller to index than a UUID, which matters at scale for database primary keys — sequential-ish IDs compress better in B-tree indexes than the effectively random distribution of UUID v4. The tradeoff is that Snowflake requires assigning and coordinating machine/worker IDs across your fleet, reintroducing a small amount of the coordination problem UUIDs were designed to avoid.

ULIDs (Universally Unique Lexicographically sortable Identifiers) split the difference: a 48-bit timestamp prefix followed by 80 bits of randomness, encoded in Base32 for shorter string representation than a UUID. ULIDs sort chronologically as strings, which UUID v4 cannot do, while still requiring zero coordination between generators. For new systems where index locality and rough time-ordering matter — event logs, time-series records — ULID is often a better fit than UUID v4; for maximum compatibility with existing tooling, database column types, and the broadest ecosystem support, UUID v4 remains the safer default.

Frequently Asked Questions

What is UUID v4?

UUID v4 is a 128-bit identifier generated using cryptographic randomness. The canonical format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx — the 4 in position 13 encodes the version, and y in position 17 is one of 8, 9, a, or b, encoding the RFC 4122 variant. Of the 128 bits, 122 are randomly generated, yielding approximately 5.3 × 10³⁶ possible values. This is the most widely used UUID version for generating primary keys, session identifiers, and request IDs in web services, databases, and distributed systems because it requires no coordination, no network call, and no shared state between generators.

Are UUIDs from this tool truly random?

Yes. This tool uses crypto.randomUUID(), which is the browser's native UUID v4 generator backed by the operating system's entropy source (on Linux, this is /dev/urandom; on Windows, it uses the BCryptGenRandom API; on macOS, it uses the arc4random family). This is a cryptographically secure pseudorandom number generator (CSPRNG), meaning the output is statistically indistinguishable from true randomness and computationally infeasible to predict. These UUIDs are suitable for security-sensitive use cases including session tokens, CSRF tokens, database primary keys, and API keys, in addition to ordinary unique identifier use cases.

What is the difference between UUID v4 and UUID v5?

UUID v4 is randomly generated — every call to crypto.randomUUID() produces a completely independent identifier with no relationship to any previous value. UUID v5 is deterministic — it derives a UUID by hashing a namespace UUID together with a name string using SHA-1, then formatting the first 128 bits as a UUID with version bits set to 5. The same namespace and name always produce the same UUID v5, making it reproducible and verifiable. Use v4 for new database records, session IDs, and correlation IDs where each value must be unique. Use v5 when you need a stable, canonical UUID for a specific named entity — for example, to consistently derive the same identifier for a given URL, product code, or username across multiple systems or pipeline runs without storing a mapping table.