What is the difference between UUID and ULID?

UUID v4 is fully random. ULID is lexicographically sortable and encodes a timestamp, making it useful for database indexes and chronological ordering without a separate created_at column.

Are these UUIDs cryptographically random?

UUID v4 and ULID use the Web Crypto API's getRandomValues for cryptographically secure randomness. UUID v1 uses a MAC address and clock; UUID v5 is deterministic from a name and namespace.

What format are the generated IDs?

UUIDs are 36 characters with hyphens (8-4-4-4-12). ULIDs are 26 characters in Crockford Base32 (no hyphens). Toggle uppercase and hyphens as needed.

Can I generate multiple IDs at once?

Yes. Set the count parameter to generate up to hundreds of IDs in one operation, each on a separate line.

Is UUID v1 safe to use?

UUID v1 encodes the host MAC address and clock time, which can leak machine identity and timing. Prefer v4 or ULID for privacy-sensitive contexts.

How does UUID v5 work?

UUID v5 is deterministic: given the same namespace and name, it always produces the same UUID. Useful for stable IDs derived from names (e.g. URLs, email addresses).

Generador de UUID / ULID

Generate UUID v1, v4, v5, and ULID identifiers. Gratis, privado y 100% del lado del cliente.

param.versionparam.countparam.uppercaseparam.hyphens

Entrada

Probar un ejemplo:

Salida

Local only

Historial reciente

Sin historial aún

Uso

Select the version: UUID v1, v4, v5, or ULID.
Set the count of IDs to generate.
Toggle uppercase and hyphens as needed.
Copy the generated identifiers.

Tareas que usan esta herramienta

Generar NanoIDs for compact unique identifiers

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Generar RSA key pair and inspect self-signed certificate fields

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Generar Snowflake IDs for distributed systems

Snowflake IDs (Twitter) combine timestamp, machine ID, y sequence número para único, sortable IDs en distributed sistemas sin coordination.

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Generar ULIDs for time-sortable identifiers

ULID (Universally Único Lexicographically Sortable Identifier) combines un timestamp con random datos, producing IDs ese ordenar por creation time.

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Pipelines que usan esta herramienta

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Generar UUID y codificar Base64

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Preguntas frecuentes

What is the difference between UUID and ULID?: UUID v4 is fully random. ULID is lexicographically sortable and encodes a timestamp, making it useful for database indexes and chronological ordering without a separate created_at column.
Are these UUIDs cryptographically random?: UUID v4 and ULID use the Web Crypto API's getRandomValues for cryptographically secure randomness. UUID v1 uses a MAC address and clock; UUID v5 is deterministic from a name and namespace.
What format are the generated IDs?: UUIDs are 36 characters with hyphens (8-4-4-4-12). ULIDs are 26 characters in Crockford Base32 (no hyphens). Toggle uppercase and hyphens as needed.
Can I generate multiple IDs at once?: Yes. Set the count parameter to generate up to hundreds of IDs in one operation, each on a separate line.
Is UUID v1 safe to use?: UUID v1 encodes the host MAC address and clock time, which can leak machine identity and timing. Prefer v4 or ULID for privacy-sensitive contexts.
How does UUID v5 work?: UUID v5 is deterministic: given the same namespace and name, it always produces the same UUID. Useful for stable IDs derived from names (e.g. URLs, email addresses).