Bulk UUID Generator
Generate one or thousands of UUIDs and GUIDs instantly. Choose your version, format, and quantity, then copy or download the results.
Version
Fully random. Best for general-purpose unique IDs.
Quantity
Format
Your UUID
v4-
32 hex characters + 4 hyphens
0 UUIDs generated
v4Showing 500 of . Download to get all.
Choose your version, set your quantity, copy or download.
The presets handle the most common quantities in one click. Custom input handles everything else, up to 10,000 at a time.
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1
Choose your UUID version. v4 is fully random and the right choice for the vast majority of use cases. v7 encodes a Unix millisecond timestamp in the most significant bits, making IDs sort in creation order, which is the recommended choice for database primary keys in new projects. v1 is an older timestamp format kept here for compatibility with systems that already use it.
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2
Set the quantity using the preset buttons (1, 10, 100, or 1,000) or type any number up to 10,000 in the custom field. The tool generates all UUIDs in memory instantly, so even large batches are ready in milliseconds.
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3
Pick your format. Standard lowercase with hyphens (550e8400-e29b-41d4-a716-446655440000) is the most widely compatible. Toggle uppercase if your system requires it, or remove hyphens to get a compact 32-character string for databases or code that strips them.
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4
Copy a single UUID, copy all as newline-separated text, CSV, or a JSON array, or download as a file. The download option is the fastest way to seed a database or import IDs into a script without pasting.
Who uses a UUID generator?
UUIDs are one of the most practical tools in software development. Here are the most common reasons developers and non-developers reach for one.
Database seeding
Generate primary key values for test records, fixture files, and seed scripts. Download as JSON or CSV and import directly into PostgreSQL, MySQL, or MongoDB without writing a script.
API and test data
Create realistic UUID values for mock API responses, unit test fixtures, and Postman collections. Export as a JSON array and paste directly into your test files.
Distributed systems
UUIDs let distributed services assign unique IDs without coordinating with a central sequence generator. Use v4 for fully independent nodes, v7 for time-ordered records with good index locality, or v1 for compatibility with existing systems.
What exactly is a UUID, and how unique is it really?
The short answer: unique enough that collisions are not a practical concern for any real-world use case.
The structure
A UUID (Universally Unique Identifier) is a 128-bit value defined by RFC 4122. It is written as 32 hexadecimal digits in five groups separated by hyphens: 8-4-4-4-12. GUID is Microsoft's name for the same standard. The two terms are fully interchangeable.
The collision math
A v4 UUID has 122 random bits, giving roughly 5.3 x 1036 possible values. To reach a 50% chance of even one collision, you would need to generate about 2.3 quintillion UUIDs. At one billion per second, that would take 73 years. For all practical purposes, each UUID you generate is unique.
v4 vs. v7 vs. v1
v4 uses cryptographically random bits and is the safest general-purpose choice. v7 (RFC 9562, 2024) places a 48-bit Unix millisecond timestamp in the most significant bits, so UUIDs sort in creation order and cluster well in B-tree indexes. v1 is an older timestamp format using the 1582 epoch whose timestamp fields are stored in a non-sortable arrangement, making it less useful for modern database work.
Generation method
All three versions use crypto.getRandomValues() for their random fields. v4 is entirely random. v7 and v1 additionally read Date.now() for the timestamp portion; v7 stores it as a raw Unix millisecond value, while v1 converts it to 100-nanosecond intervals from the 1582 UUID epoch.
Frequently Asked Questions
What is the difference between a UUID and a GUID?
There is no functional difference. UUID (Universally Unique Identifier) is the open-standard term defined in RFC 4122 and used by most programming languages and platforms, including Python, Java, Go, and JavaScript. GUID (Globally Unique Identifier) is Microsoft's name for the same concept, used in .NET, C#, SQL Server, and the broader Windows ecosystem. They use the same format and are fully interchangeable.
How unique is a v4 UUID? Can I really trust it?
Yes. A v4 UUID has 122 random bits, which gives approximately 5.3 x 1036 possible values. To have a 50% probability of generating even one duplicate, you would need to produce around 2.3 quintillion UUIDs. For any real-world system, UUID collisions are not a concern you need to design around. The values this tool generates use crypto.getRandomValues(), the browser's cryptographically secure random source, not the weaker Math.random().
What is the difference between v4, v7, and v1?
v4 is fully random and the safest general-purpose choice. v7 (defined in RFC 9562, published in 2024) encodes a 48-bit Unix timestamp in milliseconds in the most significant bits, so UUIDs sort lexicographically in the order they were created. This makes v7 the recommended choice for database primary keys: the timestamp prefix keeps newly inserted rows clustered together in the index, reducing page splits. v1 is an older timestamp format that uses the 1582 epoch and stores the timestamp in a non-sortable arrangement, which means v1 UUIDs do not sort in creation order lexicographically. For new projects that need a sortable UUID, v7 is preferred over v1.
Can I use UUIDs as database primary keys?
Yes, and it is a very common pattern. UUIDs as primary keys allow records to be created on multiple systems or services without a central ID sequence, which is essential for distributed architectures. The trade-off is storage size (16 bytes vs. 4-8 bytes for an integer) and, for v4, reduced index locality compared to sequential integers. For high-insert tables where index performance is critical, use v7. Its Unix-millisecond timestamp prefix keeps newly inserted rows adjacent in the B-tree, which eliminates the page-split problem that makes v4 inefficient as a primary key at scale.
Are UUIDs safe to expose in URLs and API responses?
Yes. UUIDs are URL-safe without percent-encoding, contain no personally identifiable information, and are not guessable in sequence. They are a good choice for public-facing resource identifiers in REST APIs (for example, /users/550e8400-e29b-41d4-a716-446655440000). Note that security through obscurity is not a substitute for proper authorization checks. A UUID ID does not inherently protect a resource from unauthorized access.
Why does this tool show "Simplified v1" for version 1 UUIDs?
The RFC 4122 specification for v1 UUIDs includes a MAC address as the node field to guarantee uniqueness across machines. Browsers do not expose the device MAC address for privacy reasons, so this tool uses a cryptographically random 48-bit value in its place. The resulting UUIDs are valid v1 UUIDs and are timestamp-ordered, but the node portion is random rather than hardware-derived. For testing and seeding purposes, this distinction is irrelevant.