One per line
Use newline output for fixtures, shell input, spreadsheet pasting, or a text file. Each identifier remains easy to scan and diff.
Generate and inspect
Create UUID and GUID values in the exact output you need
Select v4 or v7, choose a batch size and text format, then copy or download the result. The validator reports structure, version, variant, special Nil or Max values, and the embedded UTC time of UUID v7.
Loading the UUID generator…
Enable JavaScript to generate secure UUIDs, create bulk output, and inspect UUID structure.
Three deliberate choices
How to generate a UUID online
A UUID is easy to copy, but the version and output convention still need to match the system that will store or exchange it.
- 1
Choose UUID v4 or v7
Use v4 when you want an opaque identifier made from random bits. Use v7 when chronological byte and text ordering is useful and exposing millisecond creation time is acceptable.
- 2
Choose count and format
Generate one value or a batch. Standard hyphenated lowercase is the most interoperable default; braces and uppercase are common presentation choices in Microsoft-oriented workflows.
- 3
Copy, download, and validate
Export lines, comma-separated text, a JSON array, or SQL
VALUESrows. Validate the receiving system’s type and constraints before using generated IDs in production data.
Two names, one identifier family
What is the difference between a UUID and a GUID?
UUID means Universally Unique Identifier. GUID means Globally Unique Identifier. RFC 9562 explicitly notes that UUIDs are also known as GUIDs, and both terms usually refer to the same 128-bit identifier family. “GUID” is especially common in Microsoft and .NET documentation, while “UUID” is the standard’s term and is common across databases, web APIs, operating systems, and other language ecosystems.
The familiar text form contains 32 hexadecimal digits divided as 8-4-4-4-12: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Uppercase and lowercase hexadecimal letters are allowed by the RFC. Braces, a compact string without hyphens, and a urn:uuid: prefix are useful in particular interfaces, but the plain hyphenated form is the safest general exchange default.
A label does not change the bits. A GUID written as {919108F7-52D1-4320-9BAC-F847DB4148A8} and the lowercase UUID 919108f7-52d1-4320-9bac-f847db4148a8 can represent the same 128-bit value. Be careful when converting a Microsoft COM GUID to raw bytes: RFC 9562 identifies a known COM little-endian storage caveat. Compare documented byte order rather than assuming that formatting a string and serializing a platform structure are identical operations.
- Size
- 16 octets, or 128 bits.
- Standard text
- 32 hexadecimal digits in five hyphen-separated groups.
- Version field
- The high four bits of octet 6; visible as the first hex digit of group three.
- RFC variant
- Bits
10at the start of octet 8; group four starts with 8, 9, A, or B.
Choose from the workload
UUID v4 vs UUID v7
Both versions use the RFC variant and fit the same 128-bit UUID type. Their payload layout and operational tradeoffs are different.
PropertyUUID v4UUID v7
Primary data122 random or pseudorandom bits after version and variant.48-bit Unix millisecond timestamp plus 74 remaining bits after version and variant.
OrderingRandom values do not carry creation order.The leading timestamp supports chronological byte and standard-text order across milliseconds.
Information exposureDoes not intentionally embed a timestamp.Reveals a millisecond timestamp that can be extracted by anyone holding the value.
Typical fitGeneral opaque IDs, externally visible IDs, and established v4 schemas.New event or database IDs where time ordering and index locality matter.
Useful output, not just one button
Bulk UUID generation and formatting
JSON array
Produce quoted JSON strings with valid brackets and commas for a seed file, test fixture, or request body. Validate the surrounding application schema separately.
SQL VALUES rows
Generate parenthesized string rows as a starting point for an insert statement. Prefer your database’s native UUID column type and parameterized queries over assembling SQL from untrusted text.
GUID presentation
Select uppercase, braces, or compact text when an interface requests that presentation. These choices format the same bytes and do not create a different UUID version.
Read the important bits
RFC 9562 UUID version and variant layout
RFC 9562 replaced RFC 4122 as the current IETF UUID standard in May 2024. It keeps the familiar text layout and existing versions, clarifies bit and byte order, and standardizes newer sortable versions. The version occupies bits 48 through 51. That is why a v4 string has 4 as the first character of its third group and a v7 string has 7 there.
The RFC variant used by versions 1 through 8 begins with bits 10 in octet 8. In hexadecimal text, the first character of the fourth group is therefore 8, 9, a, or b. Checking only those two visible characters is useful but incomplete: a proper parser must also confirm all 32 hex digits and the exact group boundaries.
LiveParse generates sixteen secure random bytes for v4 and then sets the version and variant bits. For an individual v7 value it writes the current Unix millisecond timestamp into the leading six bytes, sets version and variant, and keeps the remaining payload from the browser cryptography source. A v7 batch instead uses a randomly seeded 14-bit counter followed by 60 fresh random bits so values stay increasing when several are minted in one millisecond.
- v4 shape
xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx- v7 shape
tttttttt-tttt-7xxx-[89ab]xxx-xxxxxxxxxxxx- Nil UUID
00000000-0000-0000-0000-000000000000, a special all-zero value.- Max UUID
ffffffff-ffff-ffff-ffff-ffffffffffff, a special all-one value.
Identifiers are not credentials
UUID uniqueness, randomness, and security
RFC 9562 recommends a cryptographically secure pseudorandom number generator when an implementation needs values that are hard to predict and unlikely to collide. This page uses the browser Web Cryptography API and never substitutes Math.random(). Generation fails instead of quietly falling back to a weaker source when secure randomness is unavailable.
No UUID generator can promise absolute global uniqueness without shared knowledge of every value ever created. UUIDs provide practical uniqueness through a large bit space, sound algorithms, and reliable randomness. If a duplicate would create unacceptable harm, enforce a unique constraint, handle insertion conflicts, and apply application-specific coordination or verification rather than treating probability as an absolute guarantee.
A UUID is not automatically a password, API key, session secret, signature, authorization decision, or proof of origin. UUID v7 openly contains creation time, and even a securely generated v4 should not replace a purpose-built token with adequate entropy, rotation, expiration, and server-side validation. Do not expose a database row merely because a caller can guess or present its UUID.
Local processing boundary
Generated UUIDs and values pasted into the inspector are processed in the current tab and are not submitted to a UUID API. Clipboard history, downloaded files, extensions, screen sharing, and other software on your device remain outside this boundary.
Read the complete privacy explanation →Common developer workflows
When to use a UUID generator
Database seed data
Create IDs for fixtures and migrations without coordinating an auto-increment service. Keep foreign-key relationships explicit and use native UUID storage where the database provides it.
Distributed resource creation
Mint an identifier before a record reaches a central database. Unique constraints and retry handling remain important at the persistence boundary.
API examples and tests
Generate realistic identifiers for documentation, mocks, idempotency tests, and request payloads. Do not reuse production secrets or imply that a UUID proves authorization.
Time-ordered event IDs
Use UUID v7 when leading Unix milliseconds and chronological ordering help with logs, events, or database indexes and timestamp exposure is acceptable.
Questions answered
UUID and GUID generator FAQ
Is a GUID the same as a UUID?
Usually, yes. RFC 9562 says UUIDs are also known as GUIDs. GUID is common in Microsoft ecosystems, while UUID is the standard term. Formatting conventions such as braces or uppercase do not change the underlying 128-bit value.
Which should I generate: UUID v4 or UUID v7?
Choose v4 for a random, opaque general-purpose identifier and for systems already standardized on v4. Choose v7 when time order is useful for database or event IDs and exposing millisecond creation time is acceptable. Read the detailed comparison before changing a production key strategy.
Are generated UUIDs guaranteed to be unique?
No decentralized generator can give an absolute global guarantee. Correct UUID generation makes collision probability extremely low for ordinary use. A system where duplication has serious consequences should also use a unique constraint, conflict handling, and any domain-specific coordination required.
How many random bits are in UUID v4?
UUID v4 has 122 random or pseudorandom bits. Six of the 128 total bits carry the four-bit version and two-bit RFC variant. The generator fills bytes from the browser cryptography source before applying those required bits.
Can I generate multiple UUIDs at once?
Yes. Choose a whole count from 1 through 10,000, then export one-per-line, comma-separated, JSON array, or SQL VALUES output. Large production batches are usually better generated inside the application or database transaction that consumes them.
Why does the fourth UUID group start with 8, 9, a, or b?
Those hexadecimal digits all begin with binary bits 10, the variant defined by RFC 9562. The first hex digit of the third group identifies the version. Both fields must appear at their exact positions.
Can a UUID be used as a secure token?
Do not assume so. UUID structure defines an identifier, not authentication, confidentiality, expiration, scope, or authorization. Use a purpose-built token system and enforce access on the server even when resource URLs contain unpredictable identifiers.
Are generated values uploaded or stored?
No UUID generation or inspection request is sent to a LiveParse conversion API. Values remain in page memory until replaced, reloaded, or the tab closes. Copying, downloading, extensions, and device software have their own privacy boundaries.
How can I check an existing UUID?
Paste it into the inspector above or open the dedicated UUID Validator. Strict mode requires the standard hyphenated form; normalized mode also accepts compact text, braces, and a UUID URN while reporting a normalized lowercase standard value.