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UUID Generator

Generate random UUID v4 values instantly online. Generate 1 to 25 UUIDs at once with per-UUID copy buttons. Uses the browser's built-in crypto.randomUUID() — no server required.

018b3b6db0-457a-4b04-b1b3-f6518ea8b567
02815db9a5-152d-40fb-9774-6faf3c2c31f1
03cac28daf-7d60-44f4-9228-d1c24d673a95
0458e14fb4-afe4-4cd9-97fc-84bcd53972c4
052190878d-d60b-42dc-908a-c4b32569e78d

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UUID (Universally Unique Identifier) is a 128-bit identifier standardized in RFC 9562 (previously RFC 4122). UUID v4 uses cryptographically random bits — 122 random bits plus 6 version/variant bits — producing identifiers with a collision probability so low (roughly 1 in 5.3×10^36 for each pair) that they can be generated independently across distributed systems without coordination.

UUIDs are the standard primary key format in distributed systems where auto-incrementing integers are impractical: each service or client generates IDs independently without database round-trips. PostgreSQL, MySQL, MongoDB, DynamoDB, and SQLite all support UUID primary keys. They are also used for idempotency keys in payment APIs (Stripe, Braintree) and correlation IDs in distributed tracing.

This tool generates UUID v4 identifiers using the browser's crypto.randomUUID() method, which is a CSPRNG-backed implementation guaranteed to produce cryptographically strong random values. A count selector (1, 5, 10, or 25) generates multiple UUIDs at once for bulk use cases, with per-row copy buttons and a copy-all option for the full list.

Common Use Cases

Seeding database test fixtures

Integration tests and database seed scripts need deterministic but realistic primary keys. Generating UUIDs for use as test record IDs in PostgreSQL fixtures or MongoDB seed documents avoids key collisions when multiple developers run seeds independently. Tools like Prisma, TypeORM, and Sequelize accept UUIDs as primary key values in seed scripts.

Creating idempotency keys for payment APIs

Stripe and Braintree require a unique Idempotency-Key header on payment creation requests to prevent duplicate charges from network retries. Generating a UUID v4 for each payment session and storing it alongside the pending transaction ensures that retried POST requests to the /charges or /transactions endpoint return the original response rather than creating a second charge.

Assigning correlation IDs for distributed tracing

Distributed tracing systems (Jaeger, Zipkin, OpenTelemetry) track requests across microservices using a trace ID propagated in HTTP headers (X-Request-ID, traceparent). Generating a UUID at the API gateway entry point and logging it with every downstream service call creates a correlation key for grouping log entries from a single user request across multiple services.

Generating unique filenames for uploads

Object storage systems (AWS S3, Google Cloud Storage, Cloudflare R2) require each object to have a unique key. Using the original filename as the key causes collisions when multiple users upload files with the same name. Prepending a UUID to each uploaded filename — or using a UUID as the entire key — guarantees uniqueness without scanning existing objects.

How to Use the UUID Generator

  1. Select how many UUIDs to generate using the 1 / 5 / 10 / 25 toggle.
  2. UUIDs are generated instantly and displayed in the list below.
  3. Click Copy next to any UUID to copy it individually.
  4. Click Copy All to copy all generated UUIDs as a newline-separated list.
  5. Click Regenerate to get a fresh set of UUIDs.

About UUID v4