UUID Generator
Generate UUIDs in bulk. Pick v4 (random) or v7 (time-ordered).
v4v7BatchFree to use
Version
Format
Count
How to use
- Pick version. v4 random, v7 time-ordered, or ULID (Crockford base32).
- Pick count. 1, 10, 100, or 1000.
- Click Generate. One identifier per line.
Common use cases
- Seeding database primary keys
- Generating correlation IDs
- Populating test fixtures
- Creating sortable distributed IDs (ULID)
Frequently asked questions
- What is the difference between UUID v1, v3, v4, v5, v7, and NIL?
- v1 embeds the MAC address and timestamp (largely deprecated). v3 and v5 are deterministic hashes of a name within a namespace (MD5 and SHA-1 respectively). v4 is fully random (the most common choice). v7 is time-ordered random (sortable, recommended for new database keys). NIL is the all-zeros UUID, sometimes used as a sentinel.
- When should I prefer ULID over UUID?
- ULID is also 128 bits but uses Crockford base32 (26 characters, no ambiguous chars), is lexicographically sortable, and embeds a millisecond timestamp. Prefer ULID for distributed-system IDs that need to sort by creation time without a separate timestamp column.
- What does the Format option do?
- Default outputs the canonical hyphenated form (e.g. 550e8400-e29b-41d4-a716-446655440000). UPPER produces uppercase hex. No hyphens removes the dashes (32-char form). {Braces} wraps the UUID in curly braces for languages and systems that expect that style (some Microsoft tooling).
- How random are these IDs?
- v4 and ULID use crypto.getRandomValues, the browser CSPRNG (cryptographically secure pseudorandom number generator). The collision probability for v4 is roughly 2^-122, so for any realistic batch you can treat them as universally unique.
- Can I generate up to 1000 at once?
- Yes. Pick a count of 1, 10, 100, or 1000 to seed test fixtures, populate database keys, or build a pool of correlation IDs in a single click.
- Are the IDs generated locally?
- Yes. Generation happens entirely in your browser; the values are not logged or transmitted anywhere.
Related tools
How to use
- Pick version. v4 random, v7 time-ordered, or ULID (Crockford base32).
- Pick count. 1, 10, 100, or 1000.
- Click Generate. One identifier per line.
Common use cases
- Seeding database primary keys
- Generating correlation IDs
- Populating test fixtures
- Creating sortable distributed IDs (ULID)
Frequently asked questions
- What is the difference between UUID v1, v3, v4, v5, v7, and NIL?
- v1 embeds the MAC address and timestamp (largely deprecated). v3 and v5 are deterministic hashes of a name within a namespace (MD5 and SHA-1 respectively). v4 is fully random (the most common choice). v7 is time-ordered random (sortable, recommended for new database keys). NIL is the all-zeros UUID, sometimes used as a sentinel.
- When should I prefer ULID over UUID?
- ULID is also 128 bits but uses Crockford base32 (26 characters, no ambiguous chars), is lexicographically sortable, and embeds a millisecond timestamp. Prefer ULID for distributed-system IDs that need to sort by creation time without a separate timestamp column.
- What does the Format option do?
- Default outputs the canonical hyphenated form (e.g. 550e8400-e29b-41d4-a716-446655440000). UPPER produces uppercase hex. No hyphens removes the dashes (32-char form). {Braces} wraps the UUID in curly braces for languages and systems that expect that style (some Microsoft tooling).
- How random are these IDs?
- v4 and ULID use crypto.getRandomValues, the browser CSPRNG (cryptographically secure pseudorandom number generator). The collision probability for v4 is roughly 2^-122, so for any realistic batch you can treat them as universally unique.
- Can I generate up to 1000 at once?
- Yes. Pick a count of 1, 10, 100, or 1000 to seed test fixtures, populate database keys, or build a pool of correlation IDs in a single click.
- Are the IDs generated locally?
- Yes. Generation happens entirely in your browser; the values are not logged or transmitted anywhere.