UUID Generator — Generate UUID v4 & v7 Identifiers Instantly

Every modern application needs unique identifiers — for database keys, API tokens, session IDs, distributed systems, and more. Hard-coding IDs or relying on auto-incrementing integers creates collisions, security risks, and scaling problems. Our free UUID Generator solves this by creating cryptographically strong, universally unique identifiers in one click. Choose between UUID v4 for pure randomness or UUID v7 for time-ordered identifiers, generate up to 100 at once, and copy them all to your clipboard. Everything runs in your browser — no data ever leaves your device.

What Is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier standard defined by RFC 4122 and later updated by RFC 9562. It is typically represented as a 36-character string with hyphens, like 550e8400-e29b-41d4-a716-446655440000. The "universally unique" part means that the probability of generating two identical UUIDs is astronomically small — roughly 1 in 2.71 × 10^18 for UUID v4.

UUIDs are used everywhere in software development. Databases use them as primary keys because they can be generated independently without coordination between servers. APIs use them as request IDs for tracing and debugging. Authentication systems use them as session tokens. Distributed systems use them as event IDs for log correlation. Any time you need an identifier that is guaranteed to be unique without a central authority, UUIDs are the answer.

Unlike auto-incrementing integers, UUIDs reveal nothing about the order or number of records. This makes them safer for public-facing URLs and APIs — an attacker cannot guess other resource IDs by incrementing a number.

How to Use the UUID Generator

Generating UUIDs takes just a few seconds. Select your preferred version, adjust the quantity, and click Generate.

1. Choose the UUID version. Select UUID v4 for random identifiers or UUID v7 for time-ordered identifiers. Each version has different strengths — see the comparison table below.
2. Set the quantity. Generate anywhere from 1 to 100 UUIDs at once. All UUIDs are generated independently.
3. Toggle formatting options. Enable Uppercase to get hexadecimal letters in uppercase (useful for some database systems). Enable No Dashes to produce a 32-character hex string without hyphens (common in certain APIs and legacy systems).
4. Click Generate. The tool instantly creates your UUIDs using cryptographically secure random number generation.
5. Copy individual UUIDs by clicking on any UUID in the list, or Copy All to get every UUID on separate lines.

UUID v4 vs UUID v7: Which Should You Use?

Feature	UUID v4	UUID v7
Generation Method	122 bits of random data	48-bit Unix timestamp (ms) + 74 random bits
Uniqueness	Random collision probability	Random collision probability (same entropy)
Sortable by Time	No	Yes — starts with timestamp
Database Performance	Random insert pattern causes index fragmentation	Sequential insert pattern improves index locality
Best For	General-purpose IDs, tokens, one-time keys	Database primary keys, event logs, time-series data
Standard	RFC 4122	RFC 9562 (2024)

UUID v4 has been the default choice for decades. It is simple, well-supported, and works everywhere. However, because UUID v4 values are completely random, inserting them into a B-tree database index causes random page splits and poor cache locality. For high-throughput databases, this can significantly reduce write performance.

UUID v7 solves this by embedding a millisecond-precision Unix timestamp in the first 48 bits. This means UUID v7 values are roughly sorted by creation time, which keeps database indexes organized and improves insert performance. If you are building a new system that uses UUIDs as database primary keys, UUID v7 is the modern best practice.

Key Features

Feature	Description
UUID v4 & v7 Support	Generate either version depending on your use case
Bulk Generation	Create up to 100 UUIDs in a single click
Uppercase Toggle	Output UUIDs in uppercase hexadecimal for systems that require it
No Dashes Option	Strip hyphens for compact 32-character hex strings
Click-to-Copy	Click any UUID to copy it to your clipboard instantly
Copy All	Copy all generated UUIDs as a newline-separated list
Cryptographically Secure	Uses crypto.getRandomValues() for true randomness
Privacy-First	All generation happens in your browser — no server calls

Real-World Use Cases

Database Primary Keys

Replacing auto-incrementing integers with UUIDs allows distributed systems to generate IDs independently without coordination. UUID v7 is especially useful here because its time-ordered nature keeps database indexes efficient.

API Request IDs

Assign a UUID to every incoming API request for tracing, debugging, and log correlation. When a user reports an error, you can search your logs for the request UUID and see the full request-response lifecycle.

Session Tokens and Authentication

UUIDs make excellent session identifiers because they are unpredictable and unique. Generate a UUID v4 when a user logs in, store it in your session store, and validate it on every subsequent request.

Distributed Event Systems

In microservices architectures, events need unique identifiers that can be generated by any service without a central coordinator. UUIDs ensure that two services never produce the same event ID, even when operating concurrently.

File and Resource Naming

When users upload files, using the original filename is risky — it may contain special characters, collide with existing files, or reveal internal structure. Generate a UUID for each file and use it as the storage key. This also works for generated reports, export files, and temporary resources.

Testing and Development

Developers constantly need sample UUIDs for unit tests, fixtures, and mock data. Generate a batch of 10 or 20 UUIDs, copy them all, and paste them directly into your test file or database seed script.

Anonymizing Data

When you need to replace personally identifiable information in a dataset while preserving uniqueness, UUIDs provide anonymous but distinct replacements. Each real ID maps to exactly one UUID, and the mapping cannot be reversed.

Tips and Best Practices

• Use UUID v7 for new database primary keys. The time-ordered prefix keeps your B-tree indexes healthy and improves write throughput compared to random UUID v4 values.
• Use UUID v4 for tokens and one-time identifiers. When you need pure unpredictability — session tokens, nonces, temporary passwords — UUID v4 is the right choice.
• Store UUIDs as native UUID types in your database. PostgreSQL has a native UUID type that stores the value in 16 bytes instead of 36 characters. This saves storage and improves query performance. MySQL 8.0+ also supports a native UUID type.
• Do not use UUIDs as secrets. While UUID v4 values are hard to guess, they are not designed to be cryptographic secrets. For API keys, access tokens, or encryption keys, use a dedicated tool like our Password Generator or a proper key derivation function.
• Normalize case when comparing UUIDs. UUIDs are case-insensitive by specification, but string comparisons are case-sensitive in most programming languages. Always convert to lowercase (or uppercase) before comparing.
• Prefer the hyphenated format. The standard 36-character format with hyphens is universally recognized and supported by all UUID libraries. Removing hyphens saves 4 bytes but can cause compatibility issues with some parsers.

Frequently Asked Questions

Is the UUID Generator free to use?

Yes. The UUID Generator is completely free with no usage limits, no registration, and no hidden costs. Generate as many UUIDs as you need, as often as you want.

Are the generated UUIDs truly unique?

UUID v4 uses 122 bits of randomness, which means there are 2^122 (approximately 5.3 × 10^36) possible values. The probability of generating a duplicate is so small that you would need to generate billions of UUIDs per second for millions of years before expecting a collision. For any practical application, UUID v4 values are unique.

What is the difference between UUID v4 and UUID v7?

UUID v4 is generated using random data. UUID v7 starts with a millisecond-precision Unix timestamp followed by random bits. Both are unique, but UUID v7 values are sortable by creation time, which makes them better for database indexing. Use UUID v4 for general-purpose randomness and UUID v7 when time ordering matters.

Can I generate UUIDs without hyphens?

Yes. Toggle the No Dashes option to generate 32-character hexadecimal strings without hyphens. This format is common in some APIs, legacy systems, and compact storage scenarios.

Does this tool work offline?

The tool loads in your browser and generates UUIDs using the built-in crypto.getRandomValues() API. Once the page is loaded, UUID generation works without any network requests. However, you do need an internet connection to load the page initially.

Is my data sent to any server?

No. All UUID generation happens entirely in your browser using JavaScript. No UUIDs are transmitted, logged, or stored on any server. When you leave the page, the generated values exist only in your clipboard.