UUID v4 Generator – Free Online Tool
Generate cryptographically random UUID v4 identifiers in bulk. Choose your preferred format, copy individually or all at once — no server required.
What Is the UUID Generator?
The UUID v4 Generator creates universally unique identifiers (UUIDs) instantly in your browser. UUIDs are 128-bit random identifiers formatted as 32 hexadecimal characters in the pattern xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. They are used as primary keys in databases, unique filenames, session tokens, and anywhere you need a guaranteed-unique identifier without a central coordinator.
Uses crypto.getRandomValues() for UUIDs that are effectively impossible to predict or collide.
Generate up to 100 UUIDs at once and copy them all to the clipboard with a single click.
Output as standard UUID, uppercase, no-hyphens, or braces-wrapped format for different programming environments.
Fully client-side — no server call needed. Works even without an internet connection.
How to Use
Choose a Count
Select how many UUIDs you need — from 1 to 100 — using the count field. The default is 1 for quick single-ID generation.
Select Output Format
Pick your format: standard lowercase, UPPERCASE, no-hyphens (for databases that store as a raw hex string), or {braces} format used in .NET GUIDs.
Generate
Click Generate to create your UUIDs. Each click produces a fresh set of unique identifiers using cryptographic randomness.
Copy
Click the copy icon next to a single UUID, or Copy All to grab every UUID in the list — ready to paste into your code, database, or config file.
Frequently Asked Questions
UUID stands for Universally Unique Identifier (also called GUID — Globally Unique Identifier on Windows). It is a 128-bit number formatted as 32 hexadecimal digits in the pattern xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx, where M is the version and N is the variant. UUIDs are used to uniquely identify information without a central authority.
v1 is time-based (includes MAC address — a privacy risk). v3 and v5 are name-based (deterministic hash of a namespace + name). v4 is random — the most widely used version. v7 (newer) is time-ordered random, useful for database primary keys that benefit from sequential ordering. This tool generates v4.
In theory yes, but in practice it is astronomically unlikely. A v4 UUID has 122 bits of randomness, giving 5.3×10³⁶ possible values. To have a 50% chance of a collision you would need to generate 2.7 quintillion UUIDs. For all practical purposes, UUIDs can be treated as globally unique.
Use UUIDs when you need IDs to be generated on the client, merge data from multiple databases, or expose IDs in URLs (auto-increment IDs reveal record counts). Use auto-increment when storage and index performance are the top priority, as UUID primary keys are larger and can fragment B-tree indexes.
GUID (Globally Unique Identifier) is Microsoft's term for the same concept. GUIDs are UUIDs — they follow the same RFC 4122 format. The only difference is notation: GUIDs are often wrapped in curly braces {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}. Enable the braces format option in this tool for .NET / SQL Server compatible output.
Yes — UUID v4 identifiers are not guessable (unlike sequential IDs), so they can serve as a weak form of access control for shareable links. However, for truly sensitive resources, you should always require authentication in addition to a UUID, as UUIDs are not a substitute for proper access control.
Explore More Tools
Everything you need — PDF tools, design utilities, web helpers and developer tools — all free, all in your browser.