UUID Generator
Our UUID generator creates universally unique identifiers directly in your browser, with no upload, no account, and no server involved. Choose UUID v4 for a fully random identifier or UUID v7 for a time-ordered value that sorts naturally by creation time, then generate one or many at once.
Beyond generation, the tool also validates an existing UUID and reports its version and variant. Because everything runs locally on your device, your identifiers never leave the page — which is exactly what you want when you are working with request IDs, database keys, or correlation IDs.
UUID version
v4 is fully random — best for general-purpose unique IDs where order does not matter.
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How to Use the UUID Generator
Choose UUID v4 (random) or UUID v7 (time-ordered).
Select how many UUIDs you need, from 1 up to 100 at a time.
Click "Generate UUIDs" to create them instantly.
Copy an individual UUID, or use "Copy All" for the whole list.
Download the results as a .txt file if you want them locally.
Switch to Validate mode to check an existing UUID and see its version.
What Is a UUID?
A UUID (Universally Unique Identifier), sometimes called a GUID (Globally Unique Identifier), is a 128-bit value written as 32 hexadecimal characters in five hyphen-separated groups: 8-4-4-4-12. The standard textual form looks like 7f6a0f48-2cc3-4c7b-9f76-2f7f5a0d5f12.
UUIDs are "unique" in a practical, not absolute, sense. Rather than checking a central registry, a UUID generator combines a large random space (v4), or a timestamp plus randomness (v7), so the chance of two values colliding is astronomically small. For most real-world systems — databases, APIs, and distributed services — that probability is effectively zero, which is why teams use UUIDs instead of coordinating sequential counters across services.
Developers reach for UUIDs whenever an identifier must be created independently on many machines without a central authority. They are common as primary keys, request IDs, event IDs, and correlation IDs that tie a single request across multiple services.
UUID v4 vs UUID v7
- v4 is random: UUID v4 is built almost entirely from secure random bytes, so the values have no inherent order. That makes them ideal for general-purpose IDs where sorting by creation time is irrelevant.
- v7 is time-ordered: UUID v7 starts with a 48-bit millisecond timestamp followed by random bits. Because the first characters reflect the creation time, v7 values sort chronologically, which can improve insert performance in time-series or indexed database tables.
- Pick per use case: Neither version is "better" in every situation. Use v4 when you just need a unique token; use v7 when time ordering helps with storage, logging, or debugging. The right choice depends on your application.
How UUIDs Are Structured
- Hexadecimal and hyphens: A UUID is 128 bits shown as 32 hex digits (0–9, a–f) split into five groups by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
- Version: The first digit of the third group marks the version (for example 4 for v4, 7 for v7), which tells you how the value was generated.
- Variant: The first digit of the fourth group is the variant, typically 8, 9, a, or b for the standard RFC layout. It distinguishes UUID from other 128-bit identifier schemes.
UUIDs in APIs and Databases
- Record IDs: UUIDs make excellent primary or secondary keys, especially when rows are created on multiple nodes that cannot easily agree on the next sequence number.
- Request and event IDs: APIs often attach a UUID to each request or event so a single action can be tracked through queues, logs, and services.
- Correlation IDs: A UUID passed across service boundaries lets you reconstruct a full trace of one user action across a distributed system.
UUID Generator vs UUID Validator
- Generation: The generator creates new identifiers on demand, in bulk if needed, using cryptographically secure randomness.
- Validation: The validator confirms whether a pasted string is well-formed, reports its detected version and variant, and shows the canonical format.
- Why both: You might generate IDs in one moment and later need to confirm a value someone handed you is actually a valid UUID — both tasks live in the same tool.
UUID vs GUID
- Same idea, different name: GUID is the term Microsoft and some other platforms use; UUID is the standardized name from the RFC specifications. In everyday development they refer to the same 128-bit identifier format.
- Use the standard term: When writing portable code or documentation, "UUID" is the clearer, vendor-neutral choice, while "GUID" remains common in Windows-centric contexts.
Why Generate UUIDs in the Browser?
- Privacy and security: Because generation happens on your device with the Web Crypto API, the identifiers are never transmitted to a server. Nothing you generate leaves your browser.
- Speed and offline use: There is no network round trip, so UUIDs appear instantly and the tool keeps working even if you are offline after the page has loaded.
Frequently Asked Questions
What is a UUID?
A UUID is a 128-bit universally unique identifier written as 32 hexadecimal characters in five hyphen-separated groups. It is used to label records, requests, and objects so they can be referenced without a central numbering system.
What is the difference between UUID v4 and UUID v7?
UUID v4 is almost entirely random, so its values have no inherent order. UUID v7 begins with a millisecond timestamp and then random bits, so the values sort by creation time. Use v4 for general unique IDs and v7 when time ordering helps with storage or tracing.
Are UUIDs guaranteed to be unique?
No identifier can be mathematically guaranteed unique, but UUIDs are large enough that accidental collisions are astronomically unlikely in practice. UUID v4 relies on secure randomness, while v7 combines a timestamp with randomness, making duplicates effectively impossible for normal use.
Can I generate multiple UUIDs at once?
Yes. You can choose a quantity such as 1, 5, 10, 25, 50, or 100, or enter a custom amount, then generate them all at once and copy or download the full list.
Can this tool validate a UUID?
Yes. In Validate mode, paste any UUID and the tool checks the format, reports the detected version and variant, and shows the normalized canonical form. It accepts uppercase, lowercase, hyphenated, and brace-wrapped input.
Are UUIDs generated on my device?
Yes. Generation and validation happen entirely in your browser using the Web Crypto API. Your UUIDs are never uploaded to a server, which keeps them private and lets the tool work offline.
Working with API responses? Our JSON Formatter makes them easy to read and validate.
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