Batch UUID/GUID Generator

About UUID

01 What is UUID?

UUID (Universally Unique Identifier) is a 128-bit number used to identify information in computer systems with extremely high probability of uniqueness. It is often referred to as GUID (Globally Unique Identifier) in Microsoft systems.

Standard Format:
xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx
  • 32 hexadecimal digits
  • Separated by hyphens into 5 groups
  • Format: 8-4-4-4-12

02 Common Versions

Version Basis Use Case
Version 1 Timestamp + MAC Address Guaranteed unique but exposes creation time and network card info.
Version 4 Random Numbers Most common. Based on strong random numbers. Probability of collision is infinitesimal. This tool uses v4.
Version 3/5 Namespace + String Hash Deterministic. Same input yields same UUID. v3 uses MD5, v5 uses SHA-1.

FAQ

Can UUIDs collide?
Theoretically yes, but practically impossible. The probability is so low that even generating billions per second for years would likely yield no duplicates.
Difference between GUID and UUID?
There is effectively no difference. GUID is just Microsoft's term for the standard UUID.
UUID vs Auto-Increment ID?
Auto-increment IDs are faster and smaller. UUIDs are globally unique and ideal for distributed systems, multiple databases, or when you need to generate IDs before saving to the DB.
How much space does a UUID take in a database?
If stored as a 36-char string (char(36)), it takes 36 bytes. If stored as 16-byte binary (binary(16)), it takes only 16 bytes. Binary storage is highly recommended for performance.
What is ULID? How does it relate to UUID?
ULID (Universally Unique Lexicographically Sortable Identifier) is an improvement over UUID. It is sortable by timestamp, which solves the database indexing performance issues common with random UUIDs.
Is the generated UUID secure?
Yes. This tool uses the browser's native `crypto.randomUUID()` API, leveraging the system's cryptographically strong random number generator. All generation happens locally; no data is sent to servers.
Why are UUIDs sometimes uppercase?
Hexadecimal representation is case-insensitive ('A' equals 'a'), so it doesn't matter technically. However, some legacy systems may require a specific case. Lowercase is the generally accepted standard.
Does the UUID contain my personal info?
Version 4 (Random) does not. Version 1 (Timestamp+MAC) does contain your network card's address. Version 3/5 contains a hash of the input name. For privacy, Version 4 is recommended and widely used.

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