UUID Generator
Generate cryptographically random UUID v4 values, one at a time or in bulk.
5 UUIDs
What is UUID Generator?
A UUID (Universally Unique Identifier), also known as a GUID, is a 128-bit identifier standardized in RFC 4122 that is designed to be unique across distributed systems without any central coordination or registry. It is typically rendered as 32 hexadecimal digits split by dashes into five groups, such as 123e4567-e89b-42d3-a456-426614174000, and version 4 UUIDs — the variant this tool generates — use 122 cryptographically random bits. Collisions are so improbable that two independent systems can mint UUIDs with no realistic chance of overlap, which is why they are widely used as database primary keys, request IDs, and resource identifiers. They are identifiers rather than secrets and should not be used as passwords or access tokens.
How to Use UUID Generator
- Choose how many UUIDs you want (1 to 100) using the count field.
- Pick a format: standard (lowercase with dashes), uppercase, or no dashes.
- Click "Generate" to create new UUIDs — or they regenerate automatically when you change options.
- Click any UUID to copy it, or use "Copy all" to copy the full list at once.
Examples
Standard
Input: —
Output: 123e4567-e89b-42d3-a456-426614174000
Uppercase
Input: —
Output: 123E4567-E89B-42D3-A456-426614174000
No dashes
Input: —
Output: 123e4567e89b42d3a456426614174000
Common Mistakes
- Using UUIDs as a security token or password substitute — they're unique identifiers, not secrets, and shouldn't be relied on for access control by themselves.
- Assuming UUID v1 (time-based) is more "random" or secure than v4 — it actually leaks generation time and can leak MAC address info.
- Storing UUIDs as a 36-character string in a database when a native UUID/binary(16) column type is available — wastes storage and index space at scale.
- Mixing dash and no-dash formats inconsistently across a codebase, making string comparisons fail unexpectedly.
Why Use This Tool
- Uses the browser's built-in cryptographically secure random generator — no server round-trip, no rate limit.
- Generate up to 100 at once for seeding test data or database fixtures.
- Multiple output formats (standard, uppercase, no dashes) cover the conventions used by different languages and databases.
- One-click copy for a single UUID or the entire batch.