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Kordu Tools
Developer Tools Runs in browser Updated 30 Mar 2026

UUID Generator

Generate cryptographically secure v4 and v7 UUIDs in bulk — copy individually or all at once, instantly in your browser.

Version:
Count:

Random UUIDs (v4) — fully random, suitable for most use cases.

xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
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How to use UUID Generator

  1. Choose the UUID version

    Select v4 for fully random UUIDs, or v7 for time-ordered UUIDs that sort chronologically — better for database primary keys.

  2. Set the quantity

    Choose how many UUIDs to generate: 1, 5, 10, 25, or 50.

  3. Configure formatting

    Toggle Uppercase for capital hex letters, or Hyphen-free for compact format without dashes — useful for systems that require a specific representation.

  4. Generate and copy

    Click Generate to produce the UUIDs. Copy individual UUIDs with the per-row button, or click Copy All to grab all as a newline-separated list.

UUID Generator FAQ

What is the difference between UUID v4 and v7?
v4 UUIDs are entirely random (122 random bits) and have no inherent ordering. v7 UUIDs embed a 48-bit Unix millisecond timestamp in the most significant bits, so they sort chronologically. v7 is preferred for database primary keys because sequential inserts avoid random page splits in B-tree indexes, improving write performance.

Are these UUIDs cryptographically secure?
Yes. v4 uses crypto.randomUUID (based on crypto.getRandomValues). v7 uses crypto.getRandomValues for its 74 random bits and the system clock for the timestamp. Both are cryptographically secure — suitable for session tokens, API keys, and user identifiers.

What is GUID vs UUID?
GUID (Globally Unique Identifier) is Microsoft's term for the same concept as UUID (Universally Unique Identifier). They are the same format and interchangeable. Microsoft systems (SQL Server, .NET, Windows Registry) traditionally call them GUIDs.

Can I generate UUIDs in bulk?
Yes. Use the quantity selector to generate up to 50 UUIDs at once, then click Copy All to get all of them as a newline-separated list for pasting into test fixtures, seed data, or migration scripts.

Are the generated UUIDs stored or logged?
No. UUIDs are generated in your browser and never sent to a server. They exist only in the page until you navigate away or refresh.

What is a UUID used for?
UUIDs are used as unique identifiers for database records, user IDs, session tokens, API keys, file names, distributed system node IDs, and anywhere a globally unique identifier is needed without central coordination.

What does hyphen-free format mean?
Standard UUID format is 8-4-4-4-12 hex characters with hyphens: 550e8400-e29b-41d4-a716-446655440000. Hyphen-free removes the dashes: 550e8400e29b41d4a716446655440000. Some databases, message queues, and APIs require one format or the other.

Should I use v4 or v7 for PostgreSQL primary keys?
v7 for high-write tables. Random v4 UUIDs cause frequent page splits in B-tree indexes because each new UUID is likely to land in the middle of the index. v7 UUIDs are monotonically increasing within a millisecond, so new rows append near the end of the index like sequential integers.

Can I use UUIDs as API keys?
v4 UUIDs are a common choice for API keys because they are random, non-sequential, and hard to guess. However, dedicated API key generators add extra entropy, prefix namespacing, and check-digit validation. For high-security API key generation, consider a purpose-built solution.

Background

UUID Generator produces cryptographically secure universally unique identifiers using the browser's native crypto.randomUUID (v4) and a spec-compliant v7 implementation using crypto.getRandomValues for the random bits and the current timestamp for the time bits.

Choose v4 for fully random UUIDs suitable for most use cases: session tokens, user IDs, API keys, database records, and file names. Choose v7 for time-ordered UUIDs that sort chronologically — ideal for database primary keys where insertion order matters, as they avoid random page splits in B-tree indexes (a major performance benefit over v4 keys in high-write databases like PostgreSQL and MySQL).

Generate anywhere from 1 to 50 UUIDs at once and copy them individually with the per-row copy button, or click Copy All to grab everything as a newline-separated list for pasting into code, config files, or data fixtures. Toggle uppercase or hyphen-free (compact) formatting for systems that require a specific representation.

All generation runs client-side using crypto.randomUUID and crypto.getRandomValues — nothing is sent to a server, and no UUIDs are logged or retained.

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What Is a UUID? v1 vs v4 vs v7 Explained

UUID v4 is the most widely used identifier format, but RFC 9562 (2024) introduced v7. Learn when to use v1, v4, and v7 for databases and distributed systems.