Who this helps
- Developers preparing sample records
- People studying UUID version differences
Developer Utility
UUID v1/v4 Compare Generator
Generate UUID v1 and UUID v4 at the same time and compare the differences between time-based and random-based UUIDs.
Generate UUID v1
Create example UUID v1 values and examine the characteristics of time-based UUID structures.
Generate UUID v4
Generate multiple random-based UUIDs commonly used in modern software development.
Version Comparison
Compare generation methods, recommended use cases, and considerations for UUID v1 and UUID v4.
Generation Count
5
Generation Mode
v1 + v4
v1 Results
0
v4 Results
0
UUID Generation Settings
Choose the number of UUIDs to generate and the UUID version. UUID v4 is the most common choice for general development.
Selection Guide
Use v1 to study time-based UUID fields, or v4 for random test IDs. Sorting v1 strings does not always put them in creation-time order.
Generate 1 to 100 UUIDs per version. Both mode applies the count to each version.
Generation Mode
UUID v1 Results
UUID format generated using timestamp information.
UUID v1 results will appear here.
UUID v4 Results
UUID format generated from random values.
UUID v4 results will appear here.
UUID v1 / v4 Comparison
Quickly review the differences between both UUID versions.
| Category | UUID v1 | UUID v4 |
|---|---|---|
| Generation Method | Time-based | Random-based |
| Characteristics | Generation order and timing can be partially inferred | Highly random and widely used as a general identifier |
| Recommended Usage | Studying time-based UUID structures and preparing test data | User IDs, filenames, API test IDs, and general identifiers |
| Considerations | Time-related information may be exposed depending on implementation | Does not include chronological ordering information |
Generate test IDs and compare UUID v1 with v4
Create time-based UUID v1 values and random UUID v4 values side by side. Choose one version or both, then copy or download the result. These are identifiers for data and testing, not a complete authentication-token system.
When to use this tool
- Create keys for API examples or fixtures.
- Inspect version and variant bits in sample UUIDs.
From input to a checked result
- 1
Choose v1, v4 or both versions.
- 2
Enter a whole count from 1 to 100.
- 3
Generate and review the output count for each selected version.
- 4
Copy one version, copy all results or download TXT.
Five random identifiers
- Input
- Mode: v4 Count: 5
- Result
- 5 values matching xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx
The third group's first character is 4. The fourth group starts with 8, 9, a or b.
Compare two versions
- Input
- Mode: v1 + v4 Count: 2
- Result
- 2 UUID v1 values and 2 UUID v4 values: 4 total
The count applies to each version. Actual identifiers change on each generation.
How it works
v4 uses crypto.randomUUID(), or Web Crypto random bytes with version and variant bits set. v1 combines a timestamp, a page-session clock sequence and a random node value whose multicast bit is set. The browser does not read a hardware MAC address. A monotonic timestamp adjustment avoids repeats within a page session.
Limitations
- A UUID format does not replace database uniqueness constraints or collision handling.
- v1 exposes time information and is not generally ordered chronologically by its displayed text.
- The page does not maintain v1 generator state across reloads.
- v3, v5, v6 and v7 are not generated here. Decimal counts are rounded down and clamped to 1–100.
Your data
Generation uses this browser's clock and Web Crypto. The tool does not send or persist the generated values; copies and downloaded TXT files remain under your control.
References
Related tools
- Password Generator
Create random text with selectable character classes.
- Unix Timestamp Converter
Explore how timestamps represent instants.
Frequently asked questions
Does Count 5 in both mode mean five total?
It means five v1 and five v4 values, for ten total.
Does v1 contain my computer's MAC address?
No. This tool generates a random node value for the page session.
Are UUIDs guaranteed never to collide?
No absolute guarantee is provided. Keep uniqueness checks where identifiers are stored.