How It Works

This tool generates Universally Unique Identifiers (UUIDs) using widely adopted version layouts and bit rules. You pick a UUID version (v1, v4, or v7), choose an output format (hyphenated, hex-only, braces, or URN), set how many IDs you want, and the generator creates them instantly. For convenience, you can optionally add a label prefix and switch to uppercase output if you prefer that style in logs or documentation.

Step-by-step

• 1) Choose a version: v4 for random UUIDs, v1 for time-based UUIDs, or v7 for modern time-ordered UUIDs.
• 2) Choose a format: hyphenated (canonical), hex-only, braces, or urn:uuid:.
• 3) Set a quantity: generate one ID or a bulk list for fixtures, imports, or QA scripts.
• 4) Copy or download: copy to clipboard in one click or download a .txt file for later use.

Behind the scenes, the generator uses cryptographically secure randomness for v4 and the random portions of v1/v7, and it sets the correct version and variant bits so the output matches the expected UUID layout.

Key Features

UUID versions v1, v4, and v7

Generate classic random UUIDs (v4), timestamp-based UUIDs (v1), or the newer time-ordered UUIDs (v7). If you want simple, broadly compatible IDs, v4 is a safe default. If you want time ordering for indexes and logs, consider v7.

Multiple output formats

Switch between canonical hyphenated output (8-4-4-4-12), a hex-only format for compact storage, curly-brace formatting often seen in Windows contexts, or a URN format used in some identifiers and schemas.

Bulk generation for fixtures and imports

Create many UUIDs at once for database seed files, CSV imports, test datasets, or distributed tracing samples. Bulk output is presented as one-per-line to make it easy to paste into spreadsheets or scripts.

Copy, reset, and download

One-click copy grabs the entire output list. Download creates a plain text file so you can reuse the generated IDs in offline workflows, commits, or project documentation.

Optional label prefix and uppercase mode

Add a short context label (like order, user, or trace) in front of each generated UUID for readability in logs. Uppercase output is also available if that matches your code style or team conventions.

Use Cases

• Database primary keys: Use UUIDs as unique keys across tables, services, and environments without central coordination.
• API resources: Create stable identifiers for REST endpoints, object storage keys, or event streams.
• Test data and QA: Generate realistic fixtures for automated tests, mocks, and synthetic datasets.
• Distributed systems: Use IDs for correlation, tracing, and idempotency keys in microservices.
• Imports and migrations: Pre-generate IDs for bulk inserts, CSV workflows, and migration scripts.
• Logs and analytics: Label and track jobs, sessions, and events with identifiers that won’t collide.

In short, this generator saves you from writing ad-hoc scripts every time you need UUIDs, while keeping the output consistent and standards-aligned.

Optimization Tips

Pick the right UUID version

If you only need uniqueness, v4 is simple and well supported. If you care about index locality or chronological ordering, v7 is often a better fit because it is designed to be time-ordered while retaining strong randomness. v1 is time-based but can embed time and node information, so it may be less desirable if you want to minimize metadata exposure.

Choose formats for your destination

For most apps and APIs, the canonical hyphenated format is easiest to read and widely recognized. For compact storage or systems that strip punctuation, hex-only can be useful. If you’re integrating with tooling that expects braces or a URN, select those to avoid manual transformations.

Generate in batches for repeatable workflows

When preparing seed data, imports, or documentation, generate a batch and download it. Keeping the UUID list in a file can help you reproduce scenarios and keep references stable across environments and teammates.

FAQ

Understanding UUID Versions in Practice

UUID v4: Random and widely supported

Version 4 UUIDs are built from random bits (with a few fixed bits for version and variant). They are the most common choice because they are simple, don’t encode timestamps, and work well across languages and frameworks. If your only requirement is uniqueness, v4 is usually the default recommendation. It is also a good fit for externally visible identifiers because it doesn’t directly reveal when a record was created.

One tradeoff of v4 is that the randomness makes values appear uniformly distributed. In many databases, that can scatter inserts across an index and lead to more page splits compared with time-ordered keys. For small to medium workloads that is often fine; for very high insert rates, you may prefer a time-ordered option.

UUID v1: Time-based with potential metadata exposure

Version 1 UUIDs include a timestamp component and a “node” component. Historically the node could be derived from a MAC address, which raised privacy concerns because the identifier could leak information about the generating machine. Many modern implementations use random node values instead, but the timestamp nature still means v1 IDs can reveal approximate creation time. That may be acceptable for internal identifiers, but it’s worth considering before exposing them publicly.

If you are using v1 for ordering, ensure your implementation sets the correct variant bits and uses a safe node source. Also note that v1 ordering is not purely lexicographic in canonical string form without a suitable byte reordering strategy, depending on your database and index collation.

UUID v7: Modern time-ordered UUIDs

Version 7 UUIDs were introduced to provide time ordering while retaining strong randomness. They embed a Unix epoch timestamp in milliseconds and fill the remaining bits with random data. The result is an identifier that tends to sort by creation time (especially when stored as bytes), which can improve index locality for write-heavy systems.

Because v7 includes time, it may still reveal approximate creation time, but it avoids node/MAC exposure and is designed for modern distributed systems. If your platform and libraries support v7, it can be an excellent compromise between operational performance and uniqueness safety.

Common Patterns and Best Practices

Use UUIDs for idempotency keys

In APIs and event processing, an idempotency key lets clients safely retry requests without creating duplicates. A UUID is a convenient idempotency key because it is easy to generate client-side and extremely unlikely to collide. If you store the key along with the request outcome, retries can return the original result.

Keep formatting consistent across your stack

Teams often mix formats unintentionally: some services produce uppercase strings, others produce lowercase; some include braces, others don’t. These differences can cause subtle bugs in equality checks, caching keys, or logging searches. Pick one canonical representation (often lowercase hyphenated) and standardize on it. When integrating with legacy systems that require a different format, generate the format you need rather than post-processing by hand.

Prefer binary storage when performance matters

Storing UUIDs as strings is human-friendly but can be less efficient. Many databases support native UUID types or allow storing the 16-byte value in a binary column. Binary storage reduces size and can speed up comparisons and indexing. If your system uses time-ordered UUIDs, binary storage can also preserve ordering characteristics more reliably than textual collation.

Validate UUIDs during parsing

If your application accepts UUIDs from untrusted input, validate the format early. Ensure the string matches expected length, characters, and hyphen placement (if applicable). For stricter checks, validate version and variant bits. This reduces error-handling complexity later and can prevent unexpected behavior in downstream systems.

Examples

Generating IDs for a CSV import

Suppose you are importing a list of customers into a new system and want stable IDs before running the import. Choose v4 (or v7 if you prefer time ordering), set the count to the number of rows you need, then download the output as a text file. You can paste the IDs into a spreadsheet column and export the combined data to CSV. This approach is quick and avoids having to generate IDs inside your import script.

Creating correlation IDs for logs

Correlation IDs help you follow a single request across services. Generate a small batch of UUIDs, prepend a label like trace, and paste them into test requests while developing. When you scan logs, the label makes it clear what the identifier represents, and the UUID ensures uniqueness across all environments.

Test fixtures for automated suites

Many test frameworks benefit from deterministic, readable fixtures. While UUIDs are random, you can still keep fixtures stable by generating a batch once and committing them with your test data. This tool makes it easy to refresh fixtures when you need more samples without changing the rest of your structure.