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GUID Generator Online
Use this free GUID generator online to create random version 4 GUIDs in bulk — up to 50 at a time. Choose your format (lowercase or uppercase, with or without hyphens, in braces if you need them), press Generate, and copy the whole list or single values. Every GUID is created locally in your browser from cryptographic random numbers; nothing is sent to a server.
How to use this generator
- Type how many GUIDs you need — anywhere from 1 to 50.
- Tick the format options your system expects: uppercase, braces, hyphens or not.
- Press Generate GUIDs.
- Copy the whole list with Copy all, or copy a single GUID with its own Copy button.
- Press Generate again for a fresh set — every set is newly random.
How a version 4 GUID is built
A GUID is 16 bytes shown as hexadecimal. In the hyphenated layout the bytes form five groups — 8-4-4-4-12 digits — and two details are fixed by the standard so that any tool can recognise the format:
| Part | Digits | Meaning |
|---|---|---|
| Group 1 | 8 | Random |
| Group 2 | 4 | Random |
| Group 3 | 4, starting with 4 | Version — the 4 marks a random GUID |
| Group 4 | 4, starting with 8, 9, a or b | Variant — marks the standard layout |
| Group 5 | 12 | Random |
That leaves 122 of the 128 bits truly random — an enormous space of about 5.3 × 10³⁶ values, which is why independently generated GUIDs effectively never collide.
Worked example
Set the count to 5, leave the options at their defaults (lowercase, hyphens on, no braces), and press Generate. You will get five lines in the standard shape, for example:
3f6d1c2a-9e4b-4a7f-8c1d-2e5f6a7b8c9d
Your five will differ — that is the point. But check the pattern against the table: the third group starts with 4 (version 4), and the fourth group starts with 8, 9, a or b (the variant). Tick Uppercase and the same values are simply shown in capital letters; untick Hyphens and each GUID becomes one 32-digit string. The identifier itself never changes meaning, only its dress.
FAQ
What is a GUID?
A GUID — globally unique identifier — is a 128-bit value written as 32 hexadecimal digits in five groups, like 550e8400-e29b-41d4-a716-446655440000. Software uses GUIDs as ready-made unique labels for database rows, files, orders and sessions, because they can be generated anywhere, on any machine, without asking a central server for the next number. Microsoft popularised the name GUID; the same format standardised elsewhere is called a UUID.
What is the difference between a GUID and a UUID?
In practice, almost nothing. UUID is the name in the open standard (RFC 4122, now RFC 9562); GUID is Microsoft's name for its implementation of the same format. A version 4 UUID generated on Linux and a GUID generated on Windows follow the same layout and can be used in each other's systems. This generator produces version 4 values in that shared format, so you can use them wherever either name is asked for.
How are the GUIDs on this page generated?
Each GUID is built from 16 bytes drawn from your browser's cryptographic random source — the same getRandomValues function used by security software. Two spots are then fixed by the standard: one nibble is set to 4 to mark version 4, and the top bits of one byte are set to mark the variant, which is why every generated value has a 4 in the third group and 8, 9, a or b starting the fourth group. Everything happens on your device; no GUID is sent anywhere.
Can two generated GUIDs ever be the same?
In theory yes, in practice no. A version 4 GUID has 122 random bits, giving about 5.3 × 10 to the power 36 possible values. You would need to generate billions of GUIDs per second for thousands of years before a collision became likely — the standard comparison is that the risk is smaller than being struck by a meteorite. Databases and systems worldwide rely on this, which is why GUIDs are trusted as primary keys without any central register.
Should I use uppercase, braces or no hyphens?
Follow the system you are pasting into. Most databases and code prefer the standard lowercase hyphenated form. Uppercase is common in Windows registry entries and some Microsoft tooling. Braces are used in Windows GUID literals and some configuration files. The no-hyphens 32-digit form appears in compact storage and URLs. The value is the same identifier in every dress — the options here simply format it, and case makes no difference to uniqueness.
Are these GUIDs stored or sent to a server?
No. Generation happens entirely in your browser with JavaScript, and the page neither stores nor transmits the values it creates. Once you close or refresh the page, the list is gone — copy what you need first. Because nothing leaves your device, the tool is safe to use for identifiers that will end up in private systems, test data and internal documents.