A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier), is a 128-bit label used to uniquely identify objects or entities in software systems. It is represented as a 32-character hexadecimal string divided by hyphens in the format 8-4-4-4-12 (e.g. 550e8400-e29b-41d4-a716-446655440000). The probability of collision between two randomly generated UUID v4 values is astronomically small.

Is this UUID generator private with no data storage?

Yes. This is a client-side UUID generation tool with zero data storage. All UUIDs are generated using the browser's native Web Crypto API (crypto.randomUUID() or crypto.getRandomValues()). No generated UUID is ever sent to any server, logged, stored or accessible to anyone else.

Can I generate bulk UUIDs online?

Yes. Set the Quantity field to any number up to 10,000 and click Generate UUIDs. All UUIDs are generated with the same version and format settings. Use Copy All to copy as a newline-separated list, or Download to save as a .txt file for use in scripts, databases or test data sets.

What format options are available?

You can generate UUIDs in standard lowercase format (default), uppercase, without dashes (32 hex characters), and with curly braces {} for use in Microsoft GUID contexts (e.g. .NET, C#, SQL Server). All options can be combined — e.g. uppercase without dashes, or braces with lowercase.

UUID Generator Online Free

The most private online UUID maker — generate UUID v4 and v1 identifiers instantly using the Web Crypto API. Our client-side UUID generation tool stores zero data. No registration, no upload, 100% private.
UUID v4 · UUID v1 · Bulk Generation · GUID Format · Zero Storage · Free

Generated UUID

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UUID Version

UUID v4 uses the Web Crypto API (crypto.randomUUID()) to generate a fully random 128-bit identifier. This is the most widely used version and is recommended for primary keys, API tokens and session identifiers.

Quantity & Format

How many UUIDs

Separator for bulk list

Format Options

Uppercase No Dashes Add Braces {}

All UUIDs generated locally using crypto.randomUUID() — zero data storage, no server contact.

How It Works

1. Choose Version

Select UUID v4 (random) for most use cases, or v1 (timestamp) for time-sortable identifiers.

2. Set Options

Choose quantity, output format (uppercase, no dashes, braces) and separator for bulk lists.

3. Crypto-Secure

The Web Crypto API generates UUIDs using OS-level entropy — unpredictable and collision-resistant.

4. Copy or Download

Copy individual UUIDs or the entire bulk list, or download as a .txt file for scripts and databases.

What Is a UUID and When Should You Use One?

A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier), is a 128-bit label used to uniquely identify records, objects or entities in software systems without a central authority. It is represented as 32 hexadecimal characters divided by hyphens: 550e8400-e29b-41d4-a716-446655440000.

This private UUID generator uses the browser's native crypto.randomUUID() API — introduced in modern browsers as part of the Web Crypto API. Unlike Math.random()-based UUID libraries, crypto.randomUUID() uses the OS-level CSPRNG (cryptographically secure pseudo-random number generator), making it suitable for security-sensitive identifiers including API keys, session tokens and database primary keys.

UUID Version Comparison

Version	Generation Method	Predictable?	Best For
v1	Timestamp + MAC address	Partially	Time-sortable logs, event IDs
v3	MD5 hash of namespace + name	Yes (deterministic)	Content-addressable IDs
v4	Cryptographically random	No	Primary keys, API tokens, sessions
v5	SHA-1 hash of namespace + name	Yes (deterministic)	Content-addressable IDs

UUID v4 is the most widely used version. The probability of collision between two v4 UUIDs is approximately 1 in 5.3 × 10³⁶ — effectively impossible in any real-world system.

How to Generate UUID Online Privately

This browser-based random UUID generator for developers is designed for zero friction. Here's a guide to each feature:

Single UUID Generation

The large display at the top always shows the latest generated UUID. Click ↺ Regenerate to get a new UUID with the same settings. Click Copy to copy it to your clipboard. The display updates automatically when you change version or format options.

Bulk UUID Generator Online Free No Upload

Set Quantity to any number up to 10,000 and click Generate UUIDs. All UUIDs appear in a scrollable list with per-item Copy buttons. Use Copy All to copy the full list in your chosen separator format (one per line, comma or space separated). Click Download .txt to save as a file for import into databases, test fixtures or seed scripts.

Format Options

Uppercase: 550E8400-E29B-41D4-A716-446655440000 — used in some legacy systems and display contexts.
No Dashes: 550e8400e29b41d4a716446655440000 — 32 hex characters, used in compact storage (MySQL BINARY(16), Redis keys).
Add Braces: {550e8400-e29b-41d4-a716-446655440000} — GUID format used in Microsoft .NET, C#, SQL Server and COM/DCOM contexts.

Common Uses for UUID Generation

Database primary keys: UUIDs are the standard alternative to auto-increment integer IDs — they work across distributed systems, don't expose record count, and can be generated client-side before a database write.
API tokens and idempotency keys: REST APIs use UUID v4 values as idempotency keys to safely retry operations without duplication. Payment systems, messaging queues and cloud functions all use this pattern.
Correlation and trace IDs: Microservices log a UUID per request to correlate logs across services. Generate a UUID, attach it to your HTTP request header (X-Request-ID) and trace it through the system.
File and object naming: S3 buckets, blob stores and CDNs use UUID-based object keys to prevent naming collisions in multi-user upload systems.
Test data generation: Use the bulk UUID generator to generate sets of test IDs for populating test databases, seed files or mock API responses.
Session identifiers: HTTP session tokens, OAuth state parameters and CSRF tokens are commonly UUID v4 values — unpredictable, long enough to be collision-resistant, and simple to parse.

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Frequently Asked Questions

A UUID (Universally Unique Identifier) is a 128-bit number formatted as 32 hex characters separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Also called a GUID (Globally Unique Identifier), it is used to uniquely identify records, files, API calls and software entities without a central registration authority. The probability of collision between two UUID v4 values is negligible — approximately 1 in 5.3 × 10³⁶.

UUID v4 is fully randomly generated using a CSPRNG — it contains no time or machine information. UUID v1 includes a timestamp and a node identifier (usually based on the MAC address), making v1 UUIDs time-sortable but partially predictable. UUID v4 is recommended for most applications because it does not leak system information and is fully unpredictable.

Yes. This is a client-side UUID generation tool with zero data storage. UUID v4 is generated using crypto.randomUUID() — the browser's native Web Crypto API. UUID v1 is computed using crypto.getRandomValues() for the node component. No generated UUID is ever sent to any server, logged, stored or accessible to anyone else.

Yes. Set Quantity to up to 10,000 and click Generate UUIDs. Use Copy All to copy the list in your preferred separator format (one per line, comma or space). Click Download .txt to save as a file for seeding databases, generating test fixtures or populating CSV files.

The braces format — {550e8400-e29b-41d4-a716-446655440000} — is the Microsoft GUID representation used in .NET, C#, SQL Server, COM/DCOM and Windows Registry contexts. Enable Add Braces {} in the format options to generate UUIDs in this format. The underlying value is identical — only the display format differs.