Generator & Inspector of UUID (v4, v7) & ULID
Create globally unique identifiers, decode embedded timestamps, and export batches for databases — nothing ever leaves your browser.
Version
Count: 500
Type the exact amount of IDs to generate (e.g. 500, 10,000, 100,000). Up to 500 IDs are rendered onscreen for performance, while file export includes all records.
Format
Code snippets (Dev Mode)
Native examples to generate the selected type in your stack.
import { uuidv7 } from "uuidv7";
const id = uuidv7();
console.log(id);Unique Identifier Architecture (RFC 9562 & ULID)
Technical benchmark comparing random UUID v4, time-ordered UUID v7, and ULID specs.
Standardized in RFC 9562, UUID v7 pairs a 48-bit UNIX epoch timestamp with 74 bits of entropy, yielding time-ordered primary keys with zero B-Tree index fragmentation.
UUID v4 offers 122 bits of pseudo-random entropy. Ideal for session tokens and secrets where concealing issuance timing is required.
Random UUID v4 inserts scatter randomly across leaf nodes, forcing expensive page splits. Sequential UUID v7 appends directly to the rightmost leaf.
ULID compresses 128 bits into 26 sortable characters using Crockford Base32, eliminating ambiguous glyphs (I, L, O, U) for safe URL embedding.
UUID, Database Indexing & Scale Troubleshooting
Step-by-step fixes for slow INSERT throughput, collision myths, and binary storage types.
Database `INSERT` Latency Spikes on Tables Over 1M Rows
Wasted Storage & Cache Loss from Storing UUIDs as `VARCHAR(36)`
Security & Privacy Leak: MAC Address Exposure in Legacy UUID v1
UI Freeze when Generating Massive Batches (50,000+ IDs)
Did You Know? UUID & ULID Trivia
Astronomical probabilities, the 2024 RFC 9562 milestone, and human-friendly Base32 alphabets.
More UUID v4 Combinations Than Observable Stars
122 bits offer 5.3 × 10^36 unique combinations. Generating 1 billion UUIDs every second for 85 years yields just a 50% chance of a single collision.
RFC 9562 Took Nearly 20 Years to Succeed RFC 4122
Published in May 2024, RFC 9562 officially updated the 2005 RFC 4122 specification to standardize time-ordered UUID v6, v7, and v8.
The Nil and Max UUID Boundary Constants
RFC standards define Nil (`0000...0000`) and Max (`ffff...ffff`) as mathematical boundary markers for queries.
Why ULID Excludes Letters I, L, O, and U
Crockford Base32 drops 'I' and 'L' (confusion with 1), 'O' (confusion with 0), and 'U' to eliminate unintended profanities in generated IDs.