UUID Generator
Generate UUID v4 (random) and UUID v1 (timestamp) instantly. Choose uppercase or lowercase, with or without hyphens. Copy individually or all at once. All processing runs locally in your browser — nothing is sent to any server.
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🔒 All processing happens locally in your browser — nothing is stored or sent to any server.
All processing happens locally in your browser — nothing is stored or sent to any server.
How to Use This UUID Generator
- Choose a version: v4 (random, recommended) or v1 (timestamp-based).
- Choose a format: lowercase or uppercase, with or without hyphens.
- Enter a quantity (1–100) and click Generate for one or Generate 10 (or custom) for bulk.
- Click any UUID in the list to copy it instantly, or use Copy All to copy the entire batch.
- Use Clear All to reset the list.
About UUIDs
UUIDs (Universally Unique Identifiers) are standardized 128-bit values used throughout software engineering as unique keys. The most common format is version 4 — using cryptographically secure random number generation to produce identifiers with essentially zero probability of collision. Version 1 uses the current timestamp and node information (MAC address or random ID) to produce IDs that can be sorted chronologically.
UUIDs follow the format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx where each x is a hexadecimal digit. This maps to exactly 16 bytes of binary data. The hyphens separate the fields according to the UUID specification: time_low (8 digits), time_mid (4 digits), time_hi_and_version (4 digits), clock_seq (4 digits), and node (12 digits).
This tool uses the browser's built-in crypto.randomUUID() API for v4 UUIDs (guaranteed cryptographically secure) and a JavaScript implementation for v1 UUIDs. No data is ever transmitted over the network — all generation happens locally.
Frequently Asked Questions
What is a UUID? ▼
A UUID (Universally Unique Identifier) is a 128-bit number formatted as a 36-character string (e.g. <code>550e8400-e29b-41d4-a716-446655440000</code>). UUIDs are designed to be unique across space and time, making them ideal for database primary keys, session IDs, and any context where a unique identifier is needed without a central authority.
What is the difference between UUID v4 and v1? ▼
<strong>UUID v4</strong> (random) generates 122 bits of cryptographically random data — completely unpredictable, no information about when or where it was created. <strong>UUID v1</strong> (timestamp) encodes the creation timestamp and a node ID (MAC address or random), making it sortable by creation time but potentially revealing information about the generating machine. v4 is preferred for most use cases unless you need time-sortable IDs.
Is UUID v1 secure? ▼
UUID v1 is <em>not</em> designed for security — it encodes the MAC address of the generating machine and the timestamp, which could theoretically be used to identify a device or approximate when it was created. For security-sensitive use cases (like session tokens), use UUID v4 or other cryptographically secure random identifiers.
Are UUIDs truly unique? ▼
UUIDs are designed to be unique with extremely high probability. The total UUID space is 2<sup>128</sup> — about 340 undecillion (3.4 × 10<sup>38</sup>). With v4, the chance of generating a duplicate in a trillion parallel generators running for billions of years is effectively zero. For v1, uniqueness depends on the clock not being set backwards and the node ID being unique.
Is my data sent to a server? ▼
No. UUIDs are generated entirely in your browser using the Web Crypto API (<code>crypto.randomUUID()</code> for v4) and JavaScript Date/Math.random (for v1). No network requests are made. You can use this tool offline once the page loads.
What does "no hyphens" mean? ▼
Standard UUIDs include hyphens separating the 8-4-4-4-12 hex groups. For some systems (like JavaScript object property names or certain databases), hyphens are not allowed or cause issues. The "no hyphens" option formats the UUID as a continuous 32-character hex string, which is equivalent but hyphen-free.
Can I generate multiple UUIDs at once? ▼
Yes. Enter a quantity (up to 100) in the quantity field and click "Generate 10" (or any custom number). All generated UUIDs are listed with individual copy buttons, and a "Copy All" button lets you copy the entire batch at once.