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ULID Generator & Inspector (Universally Unique Lexicographically Sortable)

Generate 128-bit Crockford's Base32 ULIDs with millisecond timestamp ordering, decode entropy components, and convert bidirectionally to UUIDv4.

Generate Quantity:
Generated ULID Identifiers (0)128-bit Base32
ULID Timestamp & Entropy Inspector
Generated Count0
Encoding StandardCrockford
Base32 Length26 Chars
B-Tree FriendlySortable

100% Client-Side Privacy

ULID generations and decoding calculations operate using native crypto.getRandomValues without any external network calls.

Lexicographical Chrono-Sorting

The high 48-bit millisecond timestamp ensures ULIDs automatically sort in exact chronological order without requiring separate index columns.

128-bit UUIDv4 Compatibility

Seamlessly decode 26-character Crockford Base32 keys into RFC 4122 hexadecimal UUIDs for complete interoperability with existing database schemas.

Technical Reference & Architecture Guide

ULID Generator & Inspector Developer Guide — Reference Guide

Technical reference for Crockford's Base32 128-bit Universally Unique Lexicographically Sortable Identifiers (ULID), millisecond timestamp unpacking, and UUIDv4 mapping.

Key Parameters & Controls

quantityinteger (1 - 100)

Number of unique sortable ULID strings to generate in a batch.

monotonicboolean

Ensure subsequent ULIDs generated within the same millisecond increment entropy monotonically.

timestampFormatstring ('iso' | 'epoch')

Representation format of the unpacked 48-bit timestamp.

uuidMappingboolean

Calculate equivalent 128-bit RFC 4122 hexadecimal UUIDv4 string representation.

Pro Tips & Best Practices

Use ULIDs as primary keys in distributed databases like PostgreSQL and MySQL to avoid B-Tree index fragmentation caused by random UUIDv4s.

Crockford's Base32 excludes characters I, L, O, and U to prevent human transcription errors and offensive words.

The first 10 characters encode the 48-bit millisecond timestamp, allowing direct chronological sorting without separate created_at columns.

Common Gotchas & Troubleshooting

Verify the ULID string adheres to Crockford Base32 and doesn't contain forbidden characters like lowercase 'l' or 'o'.

Enable monotonic entropy mode to increment the 80-bit random payload sequentially within the same timestamp tick.

Frequently Asked Questions

How is ULID superior to standard UUIDv4?▼

ULID is 128-bit compatible with UUID, but lexicographically sortable, URL-safe, case-insensitive, and compact at 26 characters.

Can I convert between ULID and UUID?▼

Yes. Both formats represent 128 bits of data and can be losslessly converted back and forth.

Are ULIDs cryptographically secure?▼

Yes. The 80-bit entropy component is generated using the browser's crypto.getRandomValues API.

Until what year does the 48-bit timestamp work?▼

The 48-bit timestamp will support dates up to approximately 10,889 AD without overflow.

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