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Unique IDs

UUID Generator

Generate UUID version 4 (UUIDv4) strings instantly in your browser.
Each generated UUID is displayed immediately and can be copied with a single click.

The tool keeps a short local history of generated UUIDs, allowing you to review and reuse recent values without regenerating them.
Up to 20 entries are stored for convenience, and the history can be cleared at any time.

This generator is useful for creating temporary identifiers, testing APIs, preparing sample data, or local development tasks.
All UUID generation and history storage are handled locally in your browser.
No generated values are sent to any server, ensuring fast and privacy-safe usage.

Guide: How to use & features

  • Enter the number of UUIDs you want and click Generate to see the list.
  • Use the copy icon on each row or the bulk copy button to send them to the clipboard.
  • Generating a large batch may take a few seconds—please wait until it finishes.
  • All generation happens locally and nothing is stored after you leave the page.

Samples: Sample input & output

Generate UUID v4 values

Input

Generate 2 UUID v4 values

Output

c4f8c3f6-5f2b-4a1a-a4a8-03d52f1bb2f7
1f9a0a33-8dd9-4c4f-9c42-c8b9d4e21d45

FAQ: FAQ

  • Which UUID version does this tool generate?

    It generates random UUIDv4 values. In the 8-4-4-4-12 form, the 13th digit is always 4 (the version) and the 17th is 8–b (the variant). Because it is not the time-based v1 or name-based v5, you cannot infer a value from its order of creation or from any input.

  • Is it safe to assume UUIDv4 values never collide?

    The chance is not literally zero, but with 122 bits of randomness it is negligible in practice — you can generate billions without a realistic collision. Just remember that "random" means "hard to predict," not a hard guarantee of uniqueness.

  • Are the values generated in the browser cryptographically secure?

    The tool uses the browser’s crypto.getRandomValues, and values are never sent anywhere. That is plenty for ordinary identifiers. It is not recommended, however, to use a UUID as a session token or a password-reset secret — use a purpose-built random/token scheme for secrets.

Use cases: Common use cases

  • Creating test and sample data

    Mass-produce unique IDs for database rows or API requests without worrying about collisions. Drop realistic-looking values straight into seed data or mock responses.

  • Issuing temporary keys and correlation IDs

    Get a collision-resistant identifier on the spot for a request (correlation) ID to trace across logs, an idempotency key, or a temporary file name.

  • Checking the format before you build

    Inspect a real UUIDv4 — its length, hyphen positions (8-4-4-4-12), and version/variant bits — while you decide on a database column type or a validation regex.

Notes: Notes & limitations

  • Work stays in your browser

    Inputs and outputs remain local. Closing the tab or clearing cache will remove any temporary state.

  • Validate critical data

    Results are helper outputs—double-check them before sending to production systems or sharing externally.

  • Large payloads depend on your device

    Very large text or files can feel slow in some browsers. Use a desktop environment for heavy workloads.
History Stores up to 20 entries

UUID Generator

UUIDs are widely used as unique identifiers for records, test data, request IDs, correlation IDs, and temporary objects. This UUID generator creates browser-side UUID values that can be copied into code, fixtures, database seeds, or debugging notes.

When it helps

  • Create test data: Generate IDs for mock records, API requests, and fixture files.
  • Trace requests: Use unique correlation IDs while debugging distributed systems.
  • Avoid manual collisions: Create identifiers that are more reliable than hand-written names or incremental test values.

Practical note

UUIDs are identifiers, not secrets. They are useful for uniqueness, but they should not be used as passwords, tokens, or access-control values unless combined with proper security design.

Articles for this tool

Introduction
2026-01-21

UUID Complete Guide: Versions, Use Cases, and Choosing Between v4 and v7

Understand UUID versions v1 through v7, how to generate them in JavaScript, Python, and Go, and why UUID v7 is quickly becoming the preferred choice for database primary keys.

Recent Articles

Use Case
2026-08-07

curl Options Cheat Sheet: What -X, -H and -d Actually Do

A reference for the curl options you meet in real API work: why -d already implies POST, how -d differs from --data-raw, the @ prefix that silently reads a file, single vs double quotes, and why -k and -L deserve more caution than they usually get.

Introduction
2026-08-06

Converting Between JSON Schema and Zod: How required Maps to .optional()

Inside a two-way converter that turns JSON Schema into a Zod schema and Zod code back into JSON Schema. Covers the inverted defaults between required and .optional(), the constraint mapping table, and how the Zod side is parsed without executing any code.

Use Case
2026-08-06

SQL Clause Order Reference: Why WHERE Can't See Your SELECT Alias

The order you write SQL clauses is not the order the database runs them. A reference for the logical execution order (FROM → WHERE → GROUP BY → HAVING → SELECT → ORDER BY → LIMIT), why aliases fail in WHERE, when to use WHERE vs HAVING, and the MySQL/PostgreSQL differences that bite.

Use Case
2026-08-06

Unified Diff Format Reference: Reading @@ Hunks in git diff Output

How to read the unified diff format git produces: what the four numbers in @@ -12,7 +12,9 @@ mean, why a one-character edit shows as a whole-line replacement, the whitespace and line-ending traps, \ No newline at end of file, combined @@@ diffs on merges, and rename detection via similarity index.

Use Case
2026-08-06

UTC to JST Reference: The 9-Hour Offset, Cheat Sheet & Timezone Pitfalls

Convert between UTC and JST (Japan Standard Time) with a cheat sheet. Covers what Z and +09:00 mean in ISO 8601, when JavaScript date parsing silently shifts by 9 hours, MySQL/PostgreSQL timezone behavior, and why GitHub Actions cron always runs in UTC.

Use Case
2026-08-04

CREATE TABLE Reference: MySQL vs PostgreSQL vs SQLite Types & Constraints

A cross-database CREATE TABLE (DDL) reference with cheat sheets for data types, auto-increment keys (AUTO_INCREMENT / IDENTITY / rowid), foreign key ON DELETE behavior, and the CHECK constraint that MySQL silently ignores.

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