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Generate random v4 UUIDs for databases, sessions, and APIs.
🆔 Generates RFC 4122 v4 UUIDs using the Web Crypto API. Used for unique IDs in databases, sessions, and distributed systems.
A UUID(Universally Unique Identifier) is a 128-bit number used as a unique ID in databases, APIs, sessions, and distributed systems. This generator creates RFC 4122 version 4 UUIDs (random) using your browser's cryptographic random source.
A UUID looks like 550e8400-e29b-41d4-a716-446655440000— 32 hex digits in 5 groups separated by hyphens. Version 4 (the most common) uses random bits except for a version indicator and a variant indicator.
The UUID Generator creates uuid generator on demand, right in your browser. Set the options you need, click generate, and the result is ready to copy. Because everything runs locally, nothing you enter or produce leaves your device.
Generators like this are useful when you need a specific output (a password, a UUID, a QR code, placeholder text) and don't want to install an app or trust an unknown website with your data. This tool is free, has no usage limits, and works the same on phone and desktop.
Common uses: people reach for this tool when they need to use a uuid v4 generator online, generate multiple uuids at once, random guid generator, or uuid for database primary key.
Browser-based tools like this one have a few real advantages over installed software or manual methods:
The UUID Generator is based on the following formula:
random bits = 128 − 6 = 122 (RFC 4122 v4) collision probability p ≈ n² / 2^123 for n generated UUIDs (birthday bound)
Variables: 128: total bits in a UUID 6: fixed bits (4 version bits plus 2 variant bits) 122: cryptographically random bits in a v4 UUID n: number of UUIDs generated p: approximate probability that at least one pair of UUIDs collides
A v4 UUID has 128 bits, but 6 are fixed by the version and variant fields, leaving 122 random bits. The birthday bound says collisions become plausible only when n approaches 2^61.5, so p stays near zero for any realistic n.
Worked example: Step 1: A v4 UUID stores 122 random bits (128 minus 6 fixed version/variant bits). Step 2: Generate n = 1 billion = 10^9 UUIDs. Step 3: p ≈ n² / 2^123 = 10^18 ÷ (1.06 × 10^37) ≈ 9.4 × 10^−20. Result: even a billion UUIDs collide with probability about 1 in 10 billion billion.
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