UUID Generator
Generate cryptographically secure UUIDs instantly. Supports UUID v1, v4, and v7 — with bulk generation and multiple output formats.
Generate universally unique identifiers (UUIDs) for databases, APIs, sessions, and development. All UUIDs are generated in your browser — nothing is sent to a server.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier standardised by RFC 4122 that is designed to be unique across all space and time — without requiring a central authority to coordinate their generation. UUIDs are represented as 32 hexadecimal characters displayed in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
UUIDs are used extensively in software development as primary keys in databases, identifiers for API resources, session tokens, file names, and anywhere a unique identifier is needed without coordination between systems. Their uniqueness guarantee makes them ideal for distributed systems where multiple servers or clients need to generate IDs independently.
UUID v1 vs v4 vs v7 — Which Should I Use?
UUID v4 is the most widely used version. It’s randomly generated using a cryptographically secure random number generator, making it completely unpredictable. Use v4 for most general purposes — database primary keys, API tokens, session IDs.
UUID v1 is time-based, incorporating the current timestamp and the MAC address of the generating machine. This means v1 UUIDs are sortable by generation time but expose information about when and where they were created — a privacy consideration in some applications.
UUID v7 is the newest version (RFC 9562, 2024). It combines a Unix timestamp with random data, making UUIDs time-ordered while remaining unpredictable. This is ideal for database primary keys where you want natural time-based ordering without the privacy concerns of v1.
How Are UUIDs Generated?
This tool uses your browser’s built-in crypto.randomUUID() API for UUID v4 generation — the same cryptographically secure random number generator used by your operating system. For v1 and v7, the tool uses a JavaScript implementation. All generation happens entirely in your browser — no UUIDs are transmitted to any server.
where x = random hex digit, y = 8, 9, a, or b
Example: 550e8400-e29b-41d4-a716-446655440000
UUID v7 format: tttttttt-tttt-7xxx-yxxx-xxxxxxxxxxxx
where t = Unix timestamp ms, x = random, y = variant bits
Example: 018e3a1c-7b2d-7f3a-a4b2-1c3d5e7f9012
How to Use This UUID Generator
Select your UUID version (v4 for general use, v7 for database primary keys, v1 for time-based needs). Choose how many UUIDs to generate (1–100). Select your preferred case and output format. Click Generate — your UUIDs appear instantly. Click the copy button next to any UUID to copy it individually, or use “Copy All” to copy the entire list.
UUID Output Formats Explained
Standard: The default RFC 4122 format with hyphens — 550e8400-e29b-41d4-a716-446655440000. Use this for most applications. No Hyphens: The 32-character hex string without separators — commonly used in some databases and APIs that don’t accept hyphens. With Braces: {550e8400-e29b-41d4-a716-446655440000} — used in Windows registry, .NET, and some COM applications. Quoted: Wrapped in double quotes for direct use in JSON strings. JS Array: Formats all generated UUIDs as a JavaScript array for direct use in code.
Are These UUIDs Safe to Use in Production?
Yes — UUID v4 uses crypto.randomUUID() which is a cryptographically secure pseudorandom number generator (CSPRNG). The probability of two UUID v4 values colliding is astronomically small — roughly 1 in 5.3 × 10³⁶. For all practical purposes, UUIDs generated by this tool are guaranteed to be unique. They are safe for use as database primary keys, API identifiers, and session tokens.
UUID vs ULID vs CUID — What’s the Difference?
UUIDs are the most widely supported standard, available natively in virtually every programming language and database. ULID (Universally Unique Lexicographically Sortable Identifier) is a newer alternative that is URL-safe and sortable by creation time. CUID (Collision-Resistant Unique ID) is designed for horizontal scaling with a different character set. For most projects, UUID v4 or v7 is the right choice due to universal database and language support.
Using UUIDs as Database Primary Keys
UUIDs are excellent database primary keys in distributed systems where multiple nodes need to generate IDs independently without coordination. The main trade-off vs integer auto-increment keys is storage (16 bytes vs 4–8 bytes) and index performance — random UUID v4 values cause index fragmentation in B-tree indexes. UUID v7 solves this by being time-ordered, maintaining index locality while preserving uniqueness. PostgreSQL, MySQL 8+, and SQL Server all have native UUID column types.
Frequently Asked Questions
crypto.randomUUID() — a cryptographically secure random number generator seeded by your operating system’s entropy sources (hardware events, timing, etc.). This is the same quality of randomness used for SSL/TLS and encryption. They are cryptographically random and unpredictable.xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where the ‘4’ identifies version 4 and ‘y’ is constrained to 8, 9, a, or b to indicate the RFC 4122 variant. UUID v4 is the most common UUID version in use today.crypto.randomUUID(). In Python: import uuid; uuid.uuid4(). In Java: UUID.randomUUID(). In PHP: Str::uuid() (Laravel) or ramsey/uuid package. In PostgreSQL: gen_random_uuid(). In SQL Server: NEWID(). In Go: use the google/uuid package. All modern languages and frameworks have native UUID generation support.Explore All NerdyTools By Categories
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