Bulk UUID/ULID Generator

Generate up to 1,000 V4 UUIDs, V7 UUIDs or monotonically incrementing ULIDs with one click. Export as CSV, JSON and plaintext.

Differences between UUID v4, UUID v7 and ULID

  • UUID v4: 128 bit random, RFC 4122. Ideale per chiavi senza ordinamento.
  • UUID v7: Prefisso timestamp ms + random, RFC 9562. Ordinabile lessicograficamente.
  • ULID: 48-bit timestamp + 80-bit random, Crockford Base32. Compatto e sort-safe.

Come utilizzare Generatore Bulk UUID / ULID

Set quantity and ID format

Choose the number of identifiers to generate (1-1000) and select format: UUID v4 (pure random), UUID v7 (with timestamp prefix), or ULID (monotonic, Base32 Crockford).

Choose output format

Select how you want to receive the result: plain text (one per line), JSON array or CSV with column index, based on how you will use it (script, seed database, import).

Generate and copy or download IDs

Click "Generate" to create the list, then use "Copy all" to paste it elsewhere or "Download" to save it as a file with the correct extension (.txt, .json, .csv).

Suggerimenti

  • For seed of test database, use the CSV format: the additional column index makes direct import simpler to tools like pgAdmin or SQL scripts.
  • If you need to order IDs chronologically (e.g., logs, events), prefer UUID v7 or ULID over UUID v4.

Domande frequenti

What is the main difference between UUID v4, UUID v7 and ULID?

UUID v4 is completely random (128-bit random, RFC 4122) and not sortable. UUID v7 includes a timestamp prefix in milliseconds (RFC 9562) and is lexicographically sortable like a primary key. ULID uses a 48-bit timestamp plus 80-bit random encoded in Base32 Crockford: compact, readable, and sort-safe like UUID v7.

When should you use UUID v7 or ULID instead of UUID v4 as a primary key?

When the primary key is indexed in a relational database: UUID v4 causes fragmentation of the B-tree index due to its total randomness, while UUID v7 and ULID, being time-ordered, maintain sequential inserts and improve write/indexing performance.

Are generated IDs really unique and safe from collisions?

UUID v4 uses browser crypto.randomUUID() (CSPRNG), so the collision probability is negligible. UUID v7 and ULID combine timestamp and random component: even with many IDs in the same millisecond, the risk of collision is still greatly reduced.

Why is the maximum number that can be generated 1000?

It's a practical limit set by the tool to keep the interface reactive in the browser during bulk generation. For volumes above it's preferred to generate IDs directly in the application code using standard libraries (crypto.randomUUID, uuid, ulid).

Are generated IDs sent or saved to a server?

No, generation occurs entirely in the browser via native crypto APIs: no ID passes through the network or is saved on the server.