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Generate UUIDs

Generate UUID v4, v7 and v1, ULID and Nano ID values in bulk with a cryptographically secure generator that runs in your browser.

Up to 10,000

0 IDs
Press Generate.

Decode a UUID or ULID

Runs in your browser · no uploadHow it works

How to use UUID generator

  1. 1

    Choose the ID type

    Pick UUID v4 for plain random IDs, v7 or ULID for time-sortable keys, v1 for legacy systems, or Nano ID for short strings.

  2. 2

    Set the format and amount

    Toggle uppercase, hyphens or braces, choose lines, commas or JSON, and enter how many you need.

  3. 3

    Generate and copy

    Press Generate, then copy one ID, copy the whole list or download it as a file.

  4. 4

    Decode an existing ID

    Paste a UUID or ULID into the decoder to see its version, variant and creation time.

Limits and Pro

Free: generate up to 10,000 IDs per click, with copy and .txt or .json download; decoding is unlimited.

Pro raises bulk generation to 100,000 IDs per click and removes the ads. See Pro

About UUID generator

Universally unique identifiers let separate systems create IDs without asking a central server, and the version you pick decides what is inside those 128 bits. Version 4 is 122 bits of pure randomness. Version 7, standardised in RFC 9562 in 2024, starts with a Unix timestamp in milliseconds, so new rows land at the end of a database index instead of scattering across it. Version 1 encodes a Gregorian timestamp and a node ID; this generator always uses a random node with the multicast bit set, never your network card's MAC address.

Two non-UUID formats are included. A ULID packs the same millisecond timestamp and 80 random bits into 26 Crockford Base32 characters that sort as plain text. A Nano ID is a short random string — 21 URL-safe characters by default — with a length and alphabet you can change, while the page shows how many IDs you could create before a duplicate becomes a one-in-a-billion event.

Every value comes from the browser's cryptographic random generator (crypto.randomUUID and crypto.getRandomValues) with rejection sampling, so no alphabet is biased. v7, v1 and ULIDs generated in the same millisecond still sort in creation order. Bulk lists can be uppercase, without hyphens or in {braces}, separated by lines, commas or as a JSON array, then copied or downloaded.

The decoder reads any UUID or ULID you paste and reports its version, variant and, for v1, v6, v7 and ULID, the moment it was created. It can't recover the name behind a v3 or v5 UUID, because those are one-way hashes.

Privacy

IDs are generated on your device with the Web Crypto API and are never sent to a server, so nobody else sees or logs them. Your chosen type and format options are remembered in local storage; generated IDs and anything you decode are not stored.

Features

Sortable v7 and ULID

Millisecond timestamps with a monotonic counter, so IDs made together stay in order.

Cryptographic randomness

Web Crypto only, no Math.random, and no MAC address in v1 IDs.

Built-in decoder

Shows version, variant and the timestamp hidden in v1, v6, v7 and ULID values.

UUID generator: frequently asked questions

Should I use UUID v4 or v7?
Use v7 for database primary keys and anything you sort or page through: its leading timestamp keeps B-tree indexes compact and inserts fast. Use v4 when an ID must reveal nothing, because a v7 value exposes when it was created to the millisecond. Both are equally unique in practice and fit the same 128-bit UUID column type.
Can two generated UUIDs ever be the same?
In theory yes, in practice no. A v4 UUID has 122 random bits, so you would need about 100 trillion of them before the chance of a single duplicate reached one in a billion. Collisions in real systems almost always come from broken random generators or copied values, which is why this page uses only the browser's cryptographic generator.
What is the difference between a UUID and a GUID?
GUID is Microsoft's name for the same 128-bit identifier. Windows tools often show GUIDs in uppercase and wrapped in braces, like {3F2504E0-4F89-11D3-9A0C-0305E82C3301}. Switch on Uppercase and Braces to produce that style. The bytes are identical, although some Microsoft APIs store the first three groups in little-endian order.
How long should a Nano ID be?
It depends on how many IDs you will create. The default 21 URL-safe characters carry 126 bits, comparable to a UUID v4. Shorter IDs are fine for small sets: the panel shows how many IDs your chosen length and alphabet support before a one-in-a-billion duplicate risk, so you can trade length against safety deliberately.
Does a v1 UUID reveal my computer's MAC address?
Classic v1 UUIDs embed the network card's MAC address in the last 12 hex digits, which identifies the machine. This generator never does that: it picks a random 48-bit node and sets the multicast bit, as RFC 9562 recommends. The decoder flags v1 values from other sources whose node looks like a real MAC address.

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