UUID Generator: What Is UUID v4 and When to Use It

What Is a UUID?

A UUID (Universally Unique Identifier), also known as GUID (Globally Unique Identifier), is a 128-bit value used to uniquely identify information in computer systems. A UUID looks like:

550e8400-e29b-41d4-a716-446655440000

It consists of 32 hexadecimal digits displayed in 5 groups separated by hyphens: 8-4-4-4-12.

UUID Versions Explained

Version	Method	Use Case
v1	Timestamp + MAC address	When you need time-sortable IDs (but exposes MAC)
v3	MD5 hash of namespace + name	Deterministic IDs from names (not recommended)
v4	Random	General purpose — most widely used
v5	SHA-1 hash of namespace + name	Deterministic IDs when the same input should always produce the same UUID
v7	Unix timestamp + random	Time-sortable random UUIDs — the new standard

Why Use UUIDs Instead of Auto-Increment IDs?

• ✅ Globally unique — No coordination between database nodes required.
• ✅ Unpredictable — Users can't guess other records' IDs (v4).
• ✅ Distributed systems — Generate IDs client-side without a database round-trip.
• ✅ Merging databases — No ID conflicts when merging datasets.
• ⚠️ Larger size — 128-bit vs 32-bit integers means more storage and slower index scans.

How to Generate UUIDs Online

1. Visit FavorTool UUID Generator.
2. Select the UUID version (v4 for most use cases).
3. Set the quantity — generate up to 1,000 UUIDs at once.
4. Copy or download the generated UUIDs.

UUID Probability of Collision

UUID v4 is randomly generated with 122 bits of randomness. The probability of generating a duplicate UUID is astronomically small — you'd need to generate 2.71 quintillion UUIDs to have just a 50% chance of a collision. In practice, UUID v4 collisions are impossible to encounter.