A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hex digits in 5 groups (e.g. 550e8400-e29b-41d4-a716-446655440000). It is designed to be globally unique.
UUID v4 is randomly generated using cryptographically secure random numbers. It has no dependency on time, machine identity, or sequence β making it the most commonly used version.
The probability of generating two identical UUID v4s is astronomically low (approximately 1 in 5.3Γ10Β³βΆ). In practice, collisions are essentially impossible.
Yes. This tool uses the browser's crypto.randomUUID() or crypto.getRandomValues(), which are cryptographically secure random number generators.
UUID and GUID (Globally Unique Identifier) are the same concept. UUID is the standard term; GUID is Microsoft's name for it. Both refer to the same 128-bit identifier format and are interchangeable.
UUIDs prevent ID enumeration attacks and work well in distributed systems. Auto-increment integers are smaller, faster to index, and easier to read. For most single-server web apps, integers are fine; for distributed systems or when IDs are exposed in URLs, UUIDs are preferred.
UUID v4 (random) is the right choice for most applications. UUID v7 (time-ordered) is gaining popularity as it provides better database index performance than v4 while still being random enough. Avoid v1 (MAC-address-based) for privacy reasons.
UUID v4 identifiers are used everywhere in software β database primary keys, session IDs, file names, tracking IDs, and API resources. This tool generates up to 100 cryptographically random UUIDs at once, all in your browser without any server calls.
Set the quantity
Enter how many UUIDs you need (1 to 100). For bulk database seeding or test data generation, generate batches of 50β100 at a time.
Generate
Click Generate (or the output updates automatically). Each UUID is a 128-bit random value formatted as 8-4-4-4-12 hex characters.
Copy individually or all at once
Click the copy icon next to a single UUID, or use 'Copy all' to grab the entire list. The output is newline-separated for easy pasting into scripts or spreadsheets.
Choose uppercase if needed
Toggle Uppercase to switch between lowercase (550e8400-...) and uppercase (550E8400-...) formats. Some databases and systems require a specific case.
Database primary keys
UUID primary keys prevent ID enumeration attacks (attackers can't guess sequential integer IDs) and work well for distributed systems where multiple services generate records independently.
Seed test data
Generate a batch of unique IDs when seeding a development or staging database. Copy all UUIDs into a SQL script or JSON fixture file to create realistic test records.
File and asset naming
Use UUIDs as filenames for user-uploaded content (avatars, documents) to avoid naming collisions and prevent users from guessing other users' file URLs.
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hexadecimal digits arranged in five groups: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Version 4 UUIDs are randomly generated, with approximately 5.3Γ10Β²Β² possible values β making collisions practically impossible even when generating millions of IDs per second across distributed systems. RFC 4122 defines the standard.
UUIDs are the standard choice for primary keys in databases when you need ID generation to be decentralized (client-side or multi-node without coordination), when you want to avoid sequential IDs that expose your record count, or when merging data from multiple sources. This generator uses crypto.getRandomValues() to produce cryptographically random UUIDs, not a weaker Math.random()-based approximation.