UUID Generator
Generate UUIDs (v1, v4, v7) in various formats instantly
Generator Settings
Generated UUIDs
Related Tools
YAML Formatter
Validate, format, and converting YAML to JSON
Markdown to HTML
Convert Markdown text to clean HTML with options for sanitization and preview
Regex Tester
Build, test, and debug regular expressions with live highlighting, replacement previews, and match analysis
HTML Minifier & Beautifier
Compress and optimize HTML code by removing whitespace, comments, and redundant attributes. Includes beautify mode.
CSS Minifier & Beautifier
Compress and optimize your CSS code by removing whitespace, comments, and redundant attributes. Includes beautify mode.
Javascript Minifier & Beautifier
Compress and optimize your JavaScript code by removing whitespace, comments, and redundant attributes. Includes beautify mode.
What is a UUID (Universally Unique Identifier)?
A UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify information in computer systems. Also known as GUIDs (Globally Unique Identifiers) in Microsoft systems, UUIDs are designed to be unique across space and time without requiring a central registration authority.
This free online UUID generator creates random UUIDs instantly in your browser. Generate single or bulk UUIDs in various versions (v1, v4, v7) with customizable formatting options for use in databases, APIs, distributed systems, and more.
UUID Format and Structure
UUIDs are represented as 32 hexadecimal digits, typically displayed in five groups separated by hyphens:
xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx 8-4-4-4-12 character groups = 36 characters total (32 hex + 4 hyphens)
The M position indicates the UUID version (1, 4, or 7), while the N position indicates the variant.
UUID Versions Explained
UUID v1 (Time-based)
Generated using timestamp and MAC address. Guarantees uniqueness but may expose system information. Good for ordered identifiers where creation time matters.
Use case: Database records where chronological ordering is beneficial
UUID v4 (Random)
Generated using random or pseudo-random numbers. Most commonly used version due to simplicity and privacy. Extremely low collision probability (1 in 2^122).
Use case: General purpose unique identifiers, API keys, session tokens
UUID v7 (Unix Epoch Time)
New standard combining timestamp with randomness. Provides natural sorting by creation time while maintaining privacy. Recommended for new projects.
Use case: Primary keys in databases, time-ordered distributed identifiers
Common Use Cases for UUIDs
Database Primary Keys
Use UUIDs instead of auto-increment IDs for distributed databases, data sharding, and when merging data from multiple sources.
API Resource Identifiers
UUIDs in URLs are harder to guess than sequential IDs, adding a layer of security to public-facing APIs.
File and Session Identifiers
Generate unique filenames, upload identifiers, and session tokens without collision concerns.
Distributed Systems
Create IDs across multiple servers without coordination, perfect for microservices and event sourcing.
UUID vs Alternative ID Formats
| Format | Length | Pros | Cons |
|---|---|---|---|
| UUID | 36 chars | Universal standard, no coordination | Long, not URL-friendly |
| ULID | 26 chars | Sortable, shorter | Less widely supported |
| NanoID | 21 chars | Compact, URL-safe | Not a standard |
| Snowflake | 18 digits | 64-bit, sortable | Requires worker ID setup |
Frequently Asked Questions
Can two UUIDs ever be the same?
Theoretically yes, but the probability is astronomically low. For UUID v4, you'd need to generate 2.71×10^18 UUIDs for a 50% chance of one collision.
Which UUID version should I use?
Use UUID v4 for general purposes. Use UUID v7 for new projects where time-ordering is valuable. Use UUID v1 only if you need MAC address-based uniqueness.
Are UUIDs safe to expose in URLs?
Yes, UUIDs are designed to be unguessable (especially v4). However, they don't replace authorization—always verify access permissions server-side.