UUID Generator: Generate UUIDs online
The UUID Generator creates version 1, 4, 5, and 7 UUIDs online: random, time-based, or derived from a namespace and name (v5 always produces cfbff0d1-9375-5685-968c-48ce8b15ae17 for “example.com”). Generate one or up to 100 at once, optionally in GUID format. Everything runs in your browser.
Built by Jakub Martyniak
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Runs entirely in your browser (Web Crypto API)—nothing is sent to a server, stored, or logged.
Result
Example result
What a UUID from the UUID Generator looks like
You choose a version, quantity, and format, and the tool instantly generates UUIDs to copy. The example shows version 5 because it always calculates the same UUID from a namespace and name. Versions 1, 4, and 7 are time- or random-based and produce new values with every click.
Example · Version 5, DNS namespace
Input
- Version
- Version 5 (Namespace + Name)
- Namespace
- 6ba7b810-9dad-11d1-80b4-00c04fd430c8
- The fixed DNS namespace from RFC 4122.
- Name
- example.com
Output
- UUID v5
- cfbff0d1-9375-5685-968c-48ce8b15ae17
- The digit 5 at the start of the third block indicates the version. The same name produces the same UUID everywhere.
- Formatted
- {CFBFF0D193755685968C48CE8B15AE17}
- Uppercase letters, no hyphens, with curly braces, e.g. for the Windows Registry.
Why this tool
More than just a random number
Key features of the generator.
Versions 1, 4, 5 & 7
Generate random (v4), time-based (v1/v7), and deterministic (v5) UUIDs at the click of a button.
Bulk generation
Generate up to 100 UUIDs at once—copy them together or download them as a .txt file.
Customizable format
Toggle uppercase, hyphens, and curly braces with checkboxes, for example to use GUID formatting.
Cryptographically secure
Generated using your browser's Web Crypto API, not a weak random number generator.
No account required
Just choose a version and format, then generate—no sign-up required.
Runs only in the browser
Each UUID is generated in your browser—nothing is sent to or logged by a server.
Guide
How to generate UUIDs online
From choosing a version to downloading: how to use the UUID Generator.
Step 1
Choose version
In the “Version” field, choose a UUID version: version 4 (random, default), version 1 (timestamp), version 7 (time-sortable), or version 5 (namespace + name).
Step 2
For version 5: namespace and name
Choose a namespace (DNS, URL, OID, X.500, or a custom namespace UUID) and enter a name, such as example.com.
Step 3
Set quantity
Set 1 to 100 UUIDs using the slider or plus/minus buttons. For version 5, the count is always 1.
Step 4
Customize format
Toggle uppercase letters, hyphens, and curly braces using checkboxes. Existing UUIDs are only reformatted, not regenerated.
Step 5
Regenerate
Use the refresh button next to the version to generate a new set of UUIDs. With version 5, the result remains the same for the same input.
Step 6
Copy or download
Copy a single UUID, use “Copy all,” or download the list as uuids.txt using “Download as .txt.”
UUID versions
Which UUID version should you use?
The UUID Generator creates UUID v4, v7, v1, and v5. Here’s how the versions differ and when to use them.
| Version | Basis | Typical use |
|---|---|---|
| Version 4 | 122 random bits from the Web Crypto API’s random number generator | The default choice: IDs for records, sessions, requests, or files |
| Version 7 | 48-bit timestamp in milliseconds, followed by random bits | Database primary keys that need to be sorted by creation time |
| Version 1 | Timestamp, clock sequence, and a random node ID instead of a MAC address | Systems that explicitly require time-based v1 UUIDs |
| Version 5 | SHA-1 hash of namespace and name, with no randomness | Repeatable IDs: the same input always produces the same UUID |
Version 3 is intentionally omitted: it works like version 5 but uses MD5. Browsers’ Web Crypto API does not support MD5, and RFC 4122 recommends version 5 for new applications.
Format and length
UUID or GUID: formats and length
A UUID is a 128-bit identifier made up of 32 hexadecimal digits in an 8-4-4-4-12 pattern. GUID is Microsoft’s name for the same identifier, typically written in uppercase with curly braces. You can select each format using the checkboxes in the UUID Generator.
Standard format
36 characterscfbff0d1-9375-5685-968c-48ce8b15ae17Without hyphens
32 characterscfbff0d193755685968c48ce8b15ae17With curly braces
38 characters{cfbff0d1-9375-5685-968c-48ce8b15ae17}GUID format: uppercase with braces
38 characters{CFBFF0D1-9375-5685-968C-48CE8B15AE17}Discover more
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FAQ
Frequently asked questions about the UUID Generator
Quick answers about UUIDs, GUIDs, and this tool.
One or up to 100 UUIDs in the format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Version 5 with the DNS namespace and the name example.com always produces cfbff0d1-9375-5685-968c-48ce8b15ae17, for example; with uppercase letters, no hyphens, and brackets, it becomes {CFBFF0D193755685968C48CE8B15AE17}. Versions 4 and 7 are random-based and time-based, respectively, and produce a new UUID with every click.
Yes. The UUID Generator is free and requires no account. You can generate 1 to 100 UUIDs at a time, or exactly one with version 5. Use the refresh button whenever you want a new set.
No. Every UUID is created in your browser using the Web Crypto API: crypto.getRandomValues for versions 1, 4, and 7, and SHA-1 via crypto.subtle for version 5. Nothing is uploaded, stored, or logged.
A UUID (Universally Unique Identifier) is a 128-bit identifier generated without a central authority, for example for database primary keys, session IDs, or file names. Its standard format has 36 characters: 32 hexadecimal digits and 4 hyphens in an 8-4-4-4-12 pattern. Without hyphens, it has 32 characters; with curly braces, 38.
GUID (Globally Unique Identifier) is Microsoft’s name for the same 128-bit identifier in the same text format. To get the typical GUID format {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}, enable “Uppercase” and “Curly braces” in the tool.
Version 4 is entirely random and works for most cases. Version 7 starts with a 48-bit timestamp in milliseconds, so UUIDs can be sorted by creation time, making it suitable for database primary keys. Version 1 is based on a timestamp and node ID. Version 5 uses SHA-1 to calculate the same UUID from a namespace and name every time, so the tool generates exactly one for version 5.
For practical purposes, yes. A v4 UUID contains 122 random bits from your browser’s cryptographically secure random number generator, making a collision extremely unlikely, though not mathematically impossible. Version 5 is deliberately deterministic: the same namespace and name always produce the same UUID.
No. Your browser cannot access your MAC address. For version 1, the UUID Generator therefore uses a random node ID with the multicast bit set, as specified for this case in section 4.5 of RFC 4122.
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