UUID Generator – Generate Random UUIDs Online

UUID Generator Online – Create Random UUIDs in One Click

Almost every application needs unique identifiers: database rows, uploaded files, API requests, test records, order numbers. Making them up by hand or counting 1, 2, 3 works until two systems need to create IDs at the same time without talking to each other. That is the problem a UUID solves.

This UUID generator online creates a random UUID with one click. It supports version 4 (random), version 1 (time-based) and the name-based versions 3 and 5. You can generate a single value, or bulk generate UUID lists of up to 100, copy them, and save them as a TXT or CSV file. Everything is generated in your browser.

What Is a UUID?

UUID stands for Universally Unique Identifier. It is a 128-bit value normally written as 32 hexadecimal characters split into five groups with hyphens, in an 8-4-4-4-12 pattern. An example looks like 550e8400-e29b-41d4-a716-446655440000. Microsoft environments call the same thing a GUID, so a "GUID generator" and a UUID generator produce the same kind of value.

Two characters in the string carry meaning. The first character of the third group is the version (a 4 in a v4 UUID, as in the example above). The first character of the fourth group encodes the variant. The tool shows each part in a different color under the generated value, so you can see how the string is built.

How to Generate a UUID

1. Pick a version. v4 is selected by default. Click v1, v3 or v5 to switch.
2. Click Generate UUID. A new value appears at once. One is also generated when the page loads.
3. For v3 or v5, enter a namespace and name. Choose DNS, URL, OID or X.500 and type a name such as example.com. The same namespace and name always return the same UUID.
4. Adjust the look if you need to. The Aa Case button switches between lowercase and uppercase, and the Braces button wraps the value in curly braces. Press Copy to copy exactly what is displayed.
5. Need many? Use the Bulk UUID Generator below. Set a count from 1 to 100 and click Generate All.

UUID Versions Explained

• Version 4 – random. Built from random numbers. This is the version most people want from a UUID v4 generator, and the best default for database keys, file names, request IDs and test data. The tool uses your browser's cryptographic random generator for it.
• Version 1 – time-based. The layout is based on a timestamp plus a node value. In this tool the timestamp comes from your device clock and the remaining bits are random. It is useful when you want IDs that roughly follow creation time, but it is a simplified implementation, not a drop-in replacement for the v1 values produced by a database or operating system.
• Versions 3 and 5 – name-based. These create the same UUID every time from the same namespace and name, which is handy for stable IDs derived from something like a domain or a URL. In the UUID standard, v3 uses an MD5 hash and v5 uses SHA-1.

If you are not sure which to use, choose v4.

Bulk Generation and Output Formats

The bulk section creates up to 100 UUIDs at once. Each row has its own Copy button, and the buttons above the list let you copy everything, download a .txt file with one UUID per line, or download a .csv file with an index column and a uuid column. The format bar changes how every row is written:

• Standard – lowercase with hyphens.
• UPPERCASE – the same value in capital letters.
• {Braces} – wrapped in curly braces, a style often seen in Windows tools.
• No Hyphens – 32 characters in a row.
• URN – prefixed with urn:uuid:.

Bulk lists make sense for v4 and v1. With v3 or v5, the same namespace and name always gives the same result, so a bulk list will repeat one value.

Common Uses for a UUID

• Database primary keys that can be created by the application before a row is saved.
• Test and sample data – fill a spreadsheet or fixture file with unique IDs using the CSV download.
• File and upload names that never clash with existing files.
• API request and correlation IDs for tracing one action across several services. If you keep logs or payloads in JSON, the JSON Formatter makes them easier to read.
• Printed or scannable references – turn an ID into a code with the QR Code Generator.

How Unique Is a UUID?

A random v4 UUID has 122 random bits. The chance of two identical values is so small that systems treat them as unique without checking a central list. That holds as long as the random source is good, which is why this tool relies on the browser's cryptographic generator rather than a basic random function.

Tips and Limitations

• A UUID is an identifier, not a secret. Do not use it as a password or access key. For passwords, use the Password Generator.
• Random v4 IDs are not sorted. Used as a key in some databases they can spread inserts across the index. If ordering matters to you, test with your own database.
• Version 1 here is simplified. It uses your device clock and random node bits, not a hardware address or a shared clock sequence.
• Check v3/v5 output before depending on it elsewhere. If you need v3 or v5 values that must match another library for the same input, compare a few results with that library first.
• UUIDs are safe in URLs. They contain only letters, digits and hyphens, so they need no special handling. If other parts of your link do, use the URL Encoder/Decoder. To embed a value in text that must stay plain, the Base64 Encoder/Decoder is another option.

Privacy

UUIDs are created locally in your browser. The tool does not send them to a server or store them.

Frequently Asked Questions About the UUID Generator

What is the difference between a UUID and a GUID?

None in practice. GUID is the name used in Microsoft ecosystems for the same 128-bit identifier format.

Which UUID version should I use?

Use v4 for most work. Choose v1 for time-ordered style IDs, and v3 or v5 when you need the same ID every time from the same input.

Can two UUIDs be the same?

For random v4 values the probability is negligible for any realistic use. Name-based versions deliberately repeat when the namespace and name are the same.

How many UUIDs can I generate at once?

Up to 100 per click in the bulk generator. You can click again for more.

Can I get UUIDs without hyphens or in uppercase?

Yes. Use the format bar in the bulk section for UPPERCASE, {Braces}, No Hyphens or URN, or the Aa Case and Braces buttons for the single value.

Can I download the list?

Yes, as a TXT file with one UUID per line or a CSV file with an index and a uuid column.

Is this random UUID generator free and private?

Yes. It is free, needs no sign-up, and works in your browser without sending data to a server.

Reviewed by Kromo Tools Team

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