UUID Generator: Create Unique IDs Online

What Is the UUID Generator?

The UUID Generator is a free online tool that creates UUID v4 (Universally Unique Identifier version 4) identifiers directly in your browser. UUIDs solve a fundamental problem in software development: you need unique identifiers for database records, session tokens, file names, or any entity that must be distinguishable from every other entity, even across distributed systems. UUID v4 generates this uniqueness through randomness rather than relying on a central authority or timestamp. The tool uses the native Web Crypto API (crypto.randomUUID()) built into modern browsers, which means no external library handles your data — all generation happens client-side, requires no signup, and works offline.

Key Features

• UUID v4 generation using the Web Crypto API — The component calls crypto.randomUUID() directly, the same cryptographically secure source used by your operating system's random number generator.
• Bulk generation (1–100 UUIDs) — A dropdown lets you select 1, 5, 10, 25, 50, or 100 UUIDs per generation. All are produced in a single click and displayed in a scrollable list.
• Three output formats — Choose from lowercase (550e8400-e29b-41d4-a716-446655440000), uppercase (550E8400-E29B-41D4-A716-446655440000), or braces format ({550e8400-e29b-41d4-a716-446655440000}). The format is applied at generation time, not as a display-only transformation.
• Copy individual or all UUIDs — Each UUID in the list has its own copy button. A "Copy All" button copies every UUID joined by newlines — ready to paste into a spreadsheet, seed script, or migration file.
• UUID validator — A separate input field accepts any string and checks it against the UUID v4 regex pattern ^\{?[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}\}?$ (case-insensitive, with optional braces). Validation shows a green check or red X with a descriptive message.

How to Use the UUID Generator

Step 1: Choose How Many UUIDs You Need

Open the "Count" dropdown and select a value: 1, 5, 10, 25, 50, or 100. The default is 1. If you need to seed a database table with test rows, selecting 100 lets you get an entire batch with one click.

Step 2: Select a Format

Open the "Format" dropdown and choose one of three options:

• Lowercase — The standard representation: a1b2c3d4-e5f6-4789-8abc-def012345678. This is the format most databases, frameworks, and API specifications expect.
• Uppercase — All hex characters capitalized: A1B2C3D4-E5F6-4789-8ABC-DEF012345678. Use this for systems that require uppercase, such as certain Windows registry entries.
• Braces — Lowercase UUID wrapped in curly braces: {a1b2c3d4-e5f6-4789-8abc-def012345678}. This is the GUID format expected by Microsoft technologies like COM/DCOM and some .NET libraries.

Step 3: Generate

Click the "Generate" button. The generated UUIDs appear immediately in a numbered list below the controls. Each entry shows the UUID in monospace font alongside an individual copy icon.

Step 4: Copy Your Results

For a single UUID, click the copy icon on the right of that row. For multiple UUIDs, click "Copy All" — the tool joins all values with newlines and writes them to your clipboard. You can then paste directly into a SQL INSERT statement, a CSV file, or a configuration file.

Step 5: Validate an Existing UUID (Optional)

Scroll to the "Validate UUID" section. Paste any UUID string into the input field and click "Validate." The tool checks the string against the v4 pattern and shows either a green "Valid UUID v4" indicator or a red "Invalid UUID format" message. The validator accepts lowercase, uppercase, and brace-wrapped formats.

Practical Examples

Seeding a Database with Test Records

You need 25 primary keys for a new users table in a staging environment. Select count 25, format lowercase, click Generate, then click "Copy All." Paste the result into your seed script:

INSERT INTO users (id, name) VALUES
('a1b2c3d4-...', 'Test User 1'),
('b2c3d4e5-...', 'Test User 2'),
...

Each UUID is guaranteed to be unique and safe to use as a primary key across any distributed system.

Generating a GUID for a Windows COM Component

A .NET library requires a GUID attribute on a class. Select count 1, format braces, click Generate. The output {3F2504E0-4F89-41D3-9A0C-0305E82C3301} can be pasted directly into a [Guid("...")] attribute in C#.

Validating a UUID Received from a Third-Party API

Your application received an ID from an external service and you are unsure it is a valid v4 UUID before storing it. Paste the value into the validator, click Validate, and confirm the green indicator before proceeding. This is faster than writing a regex in a scratch pad.

Tips and Best Practices

Regenerate without changing settings. After generation, a "Regenerate" button appears in the results card header. Clicking it runs a fresh generation with the same count and format without touching the dropdowns — useful when you realize you need a different set but want the same configuration.

The format applies at generation time. If you generate 10 UUIDs in lowercase, then switch to uppercase and generate again, you get a completely new set in uppercase — not the previous set reformatted. If you need the same UUID in two formats, you can run the validator on the lowercase version to confirm validity, then manually convert it.

Share settings via URL. The tool encodes your count and format selection into a shareable URL via useShareableState. If you send a colleague a link with these parameters, the tool loads with those settings pre-selected.

The clipboard fallback works in older browsers. If navigator.clipboard.writeText is unavailable — common in some corporate environments — the tool creates a temporary <textarea>, selects its content, and calls document.execCommand('copy') as a fallback.

Common Issues and Troubleshooting

"Please enter a UUID" error on validation. This appears when you click Validate with an empty input field. Paste a UUID string before clicking.

Validator shows invalid for a UUID you know is real. The validator specifically checks the UUID v4 format. UUID v1 (time-based), v3 (MD5-namespaced), and v5 (SHA1-namespaced) identifiers have different bit patterns in the version and variant fields and will fail v4 validation. If you receive a UUID v1 from a system like CockroachDB or a Cassandra cluster, the validator will correctly report it as not a v4 UUID.

Brace format rejected by a database. Most SQL databases and ORMs expect the plain hyphenated format without braces. Strip the braces before storing, or switch to lowercase or uppercase format. The validator accepts brace-wrapped input, but your database driver likely does not.

Copy button does nothing. In browsers without clipboard API access (HTTP connections in some environments, or locked-down browser profiles), the fallback document.execCommand('copy') method is used. If that also fails silently, manually select and copy the text from the monospace output field.

Privacy and Security

The UUID Generator runs entirely inside your browser. No UUIDs, no settings, and no validation inputs are transmitted to any server. The tool uses crypto.randomUUID(), which is part of the Web Crypto API and draws entropy from the operating system's cryptographically secure pseudo-random number generator — the same source used for TLS key generation. Generated UUIDs are safe to use as database primary keys, authentication tokens, or file identifiers. The tool works fully offline once the page is loaded.

Frequently Asked Questions

Is the UUID Generator free? Yes, completely free with no usage limits. No account, subscription, or payment is required. All features including bulk generation, format options, and validation are available to all users.

Does the tool work offline? Yes. Once the page has loaded, generation and validation work without an internet connection. The Web Crypto API used for generation is built into the browser and requires no network calls.

Is my data safe? Your UUIDs are generated entirely within your browser. Nothing is sent to a server. The source code runs client-side only. You can verify this by inspecting the network tab in your browser's developer tools — no outbound requests are made when you click Generate.

What is the difference between UUID and GUID? UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are the same concept. GUID is the name Microsoft uses; UUID is the name defined in RFC 4122. Both refer to a 128-bit identifier typically rendered as 32 hex characters in five groups separated by hyphens. This tool generates UUID v4, which is the random variant used in most modern applications.

Why UUID v4 and not v1 or v5? UUID v4 is the most widely used variant for application identifiers because it requires no coordination between systems, no seed data, and exposes no information about the host machine or generation time. UUID v1 embeds a timestamp and MAC address, which can expose system information. UUID v5 requires a namespace and input string, making it deterministic rather than random. For most use cases — database primary keys, session identifiers, correlation IDs — v4 is the right choice.

How unique are UUID v4 identifiers? The probability of generating a duplicate across two randomly generated v4 UUIDs is approximately 1 in 5.3 × 10³⁶. In practical terms, you would need to generate about 2.7 × 10¹⁸ UUIDs before a 50% chance of any collision exists. For the overwhelming majority of applications, the collision risk is negligible without any deduplication logic.

Can I use these UUIDs as database primary keys? Yes. UUID v4 is commonly used as a primary key type in PostgreSQL (with the uuid column type), MySQL (as a CHAR(36) or BINARY(16)), MongoDB, and most other databases. The main tradeoff versus sequential integer keys is index fragmentation in B-tree indexes; if your database handles millions of rows and you experience write performance issues, consider UUID v7 (time-ordered) or use a ULID — both are available in the ID Generator Suite tool.

What does the braces format mean? The braces format wraps the UUID in curly braces: {a1b2c3d4-e5f6-4789-8abc-def012345678}. This is the GUID notation used by Microsoft, particularly in COM/DCOM component registration, .NET's [Guid] attribute, and Windows registry entries. If you are not specifically targeting a Microsoft technology stack, the standard lowercase format is preferred.

Can I regenerate the same UUIDs? No. Each UUID v4 is generated randomly and cannot be reproduced. If you need reproducible identifiers from a given input, use UUID v5 (which hashes a namespace and name) or CUID2 (available in the ID Generator Suite tool). For most application needs, reproducibility is not required — just generate and store the UUID.

Does the validator check UUID versions other than v4? The validator specifically checks the v4 format. The fourth group of characters in a UUID encodes the version: a v4 UUID has 4 as its thirteenth character, and the first character of the third group is 8, 9, a, or b (the variant bits). UUID v1, v3, or v5 identifiers have different values in these positions and will show as invalid.

Related Tools

• UUID Generator — the focused tool covered in this guide
• ID Generator Suite — generates UUID v4, Nanoid, ULID, CUID2, Short UUID, and MongoDB ObjectID in one place
• Password Generator — generates cryptographically secure passwords using the same Web Crypto API
• Base64 Encoder/Decoder — encode UUID strings and other binary data into Base64 for transport
• JSON Formatter — format and validate JSON payloads that include UUID fields

Try the UUID Generator now: UUID Generator