Developer tools
UUID generator for v1, v4 and v7 identifiers
This UUID generator creates version 1, 4 or 7 UUIDs, one at a time or in bulk, entirely in your browser. Choose a version, a quantity, a letter case and an output format, then generate to fill the result box with ready-to-copy or downloadable identifiers.
How to generate UUIDs
To generate UUIDs, choose a Version, set Quantity, pick a Letter case and an Output format, then select Generate UUIDs. The result appears in the output box, ready for Copy all or Download .txt.
- Choose Version: v4 (Random) is selected by default; switch to v1 (Time-based) or v7 (Unix time) for a different structure and use.
- Set Quantity to any positive whole number; 5 is the default, and 1 produces a single UUID for a one-off need.
- Pick Letter case, Lowercase or Uppercase, and Output format, either plain text with one UUID per line, or a JSON array of strings.
- Select Generate UUIDs. It reports progress for a large batch. Copy all copies the list, and Download .txt (or Download .json for JSON output) saves it as
uuids-v4.txtor the matching name. Cancel stops a batch in progress; Reset restores the default settings once you have generated a batch or changed an option.
Choosing a UUID version
All three versions share the same RFC 9562 layout: 32 hexadecimal digits in five hyphenated groups, such as 3b1d653e-4a89-450b-a427-5d4810500356. The version digit (4 in that example) and the two-bit variant field are fixed by the format; only the version changes how the remaining bits are chosen.
Version 4 fills every other bit with cryptographically secure randomness, 122 random bits in total, and is a reasonable default when an identifier should not encode when or where it was created. Version 1 combines a timestamp, a clock sequence and a node identifier; this generator's node value is random, not your device's network address, and UUIDs generated in the same run may share a node. Version 7 puts a Unix millisecond timestamp first, followed by sequence and random data, so v7 values sort in creation order, though this also means a v7 UUID exposes its approximate generation time, which v4 does not.
Uniqueness and using these IDs
No generator can guarantee global uniqueness; it can only make a collision astronomically unlikely. Version 4's 122 random bits give roughly 5.3 x 10^36 possible values, so an accidental match between independently generated v4 UUIDs is not a practical concern, but two systems that must never collide should still enforce uniqueness when they store an identifier, not merely trust the generator.
Version 1 and version 7 UUIDs reveal approximate creation time and use structured, low-entropy fields alongside their random bits, so treat all three versions as identifiers rather than secrets: none should be used as a password, an authentication token or anything else that depends on being unguessable to an attacker. Time in this tool is your device's own clock, not a verified server time, and ordering across separate runs or devices is not guaranteed.
Limits
There is no batch cap set by this tool; Quantity accepts any positive whole number JavaScript can represent exactly, and generation is chunked internally every 1,024 UUIDs so the page can report progress without limiting the total. The complete output must still fit in your browser's available memory and string-length limits, so a very large batch can exhaust memory or fail before it finishes; Cancel stops generation, and a smaller quantity is the fix if generation does not complete. The largest Quantity it accepts is 9,007,199,254,740,991, JavaScript's largest safe integer; a device runs out of memory long before that.
Plain text output lists one hyphenated UUID per line; JSON output is an array of UUID strings. Both formats end with a trailing newline and download as UTF-8 text.
Questions
What does UUID mean?
UUID stands for universally unique identifier. It is a 128-bit value written as 32 hexadecimal digits in five hyphen-separated groups of 8, 4, 4, 4 and 12. The first digit of the third group is the version, so 3b1d653e-4a89-450b-… is a version 4 UUID.
What is a UUID generator?
A UUID generator makes new identifiers on request, so you do not have to build one by hand or write code. This one makes version 1, 4 or 7 UUIDs and lists them as plain text or as a JSON array.
How can I get UUID?
Select a Version, set Quantity to 1 for a single UUID, or higher for a batch, then select Generate UUIDs. Any batch that fits in your browser's memory and string-length limits generates in one pass, chunked internally every 1,024 UUIDs so the page can report progress.
Is a generated UUID actually unique?
No generator can guarantee global uniqueness, only make a collision extremely unlikely. Version 4 draws its 122 random bits from the browser's cryptographically secure random-number source, and generation fails with a clear error rather than falling back to weaker randomness if that source is unavailable.
Can I generate uppercase UUIDs?
Yes. The Letter case option formats every generated UUID as lowercase or uppercase before it reaches the output box. The choice changes only the hexadecimal letters; the digits, hyphens and the version and variant bits stay the same either way.
Can I export the generated UUIDs as JSON?
Yes. The Output format option produces plain text, one hyphenated UUID per line, or a JSON array of UUID strings. Either result can be copied in full or downloaded as a file named for the version and format you chose.
Is a GUID the same as a UUID?
GUID and UUID name the same RFC 9562 text format: 32 hexadecimal digits in five hyphenated groups. This tool's output already matches that layout, so a UUID from this tool has the text form that most systems accept as a GUID. Some tools want it inside braces.