UUID / GUID Generator
Generate up to 100 unique random Version 4 UUIDs instantly.
Generate Secure, Random UUIDs (v4 & v7) in Bulk Instantly
In modern software engineering, assigning unique identifiers to records is a core requirement. In the early days of web development, databases relied on auto-incrementing sequential integers (`1, 2, 3, 4...`).
While sequential integers work for small hobby projects, they create critical flaws in distributed production systems. Sequential IDs allow competitors to scrape your database by guessing URLs (e.g. changing `/users/104` to `/users/105`), cause primary key collisions when merging multi-region databases, and fail completely in offline-first mobile apps.
A Universally Unique Identifier (UUID)—also known as a Globally Unique Identifier (GUID) in Microsoft ecosystems—solves this cleanly. A standard UUID is a 128-bit value formatted as 32 hexadecimal digits separated into five hyphenated groups:
Our free online UUID Generator produces cryptographically secure Version 4 (v4) and modern Time-Ordered Version 7 (v7) UUIDs in single or bulk batches, with options for uppercase, lowercase, hyphens, and brackets.
Will Two Random v4 UUIDs Ever Collide? (The Math)
Developers frequently ask: If UUID v4 is purely random, isn't there a risk that two users generate the exact same ID and corrupt our database?
The Unfathomable Probability of a Collision
A UUID v4 contains 122 bits of pure cryptographic entropy. That means there are:
To have a one-in-a-billion chance of a duplicate collision, you would need to generate 1 billion UUIDs per second for roughly 85 consecutive years. You are millions of times more likely to get struck by a meteorite while holding a winning lottery ticket than encountering an accidental v4 UUID collision.
UUID Versions Explained: Which Should You Use?
UUID v4 (Random - Most Popular)
Generated using cryptographically secure pseudorandom numbers (`crypto.getRandomValues`). The universal standard for session tokens, Stripe idempotency keys, and general API resources.
UUID v7 (Time-Ordered - Best for Database Indexes)
The modern RFC 9562 standard. It encodes the current Unix epoch millisecond timestamp at the beginning, followed by random bits. Because new records sort sequentially in time, it eliminates B-Tree database page fragmentation in PostgreSQL and MySQL!
UUID v1 (Timestamp + MAC Address - Legacy)
Uses system timestamp and the physical MAC address of the network card. Deprecated for modern web apps because it exposes server hardware identity and exact creation timestamps.
3 Common Industry Use Cases
- Payment Gateway Idempotency Keys: When charging a credit card via Stripe or Razorpay, attaching a UUID as an `Idempotency-Key` header ensures that if a network glitch causes the user to tap "Pay" twice, the customer is billed only once.
- Distributed Database Primary Keys: In distributed architectures (like CockroachDB, DynamoDB, or Cassandra), microservices can generate primary keys independently without coordinating with a central sequence generator.
- Temporary File Names & S3 Upload Keys: Storing user uploads in cloud buckets like AWS S3 using UUIDs avoids filename collisions and sanitizes malicious characters.
Frequently Asked Questions
Are the UUIDs generated here cryptographically secure?
Yes. Our tool uses the browser's native `window.crypto.getRandomValues()` API, which pulls entropy directly from the underlying operating system kernel CSPRNG.
Can I generate 50 or 100 UUIDs at once?
Yes, you can generate single IDs or bulk batches of up to 500 UUIDs in one click, copy them to your clipboard, or download them as a plain text file.
Is a GUID identical to a UUID?
Yes. GUID (Globally Unique Identifier) is simply Microsoft's historical terminology for the RFC 4122 / RFC 9562 standard UUID specification.