A KSUID (K-Sortable Unique Identifier) is a 20-byte identifier made of a 4-byte timestamp and 16 random bytes, encoded as a fixed 27-character base62 string. Because the timestamp is the leading bytes, KSUIDs sort lexicographically in the same order they were created.

Why does the timestamp use a custom epoch instead of 1970?

KSUID timestamps count seconds since 2014-05-13T16:53:20Z (Unix time 1400000000), not the standard 1970 epoch. This gives the format more headroom before the 4-byte counter overflows, since KSUIDs were not needed before 2014.

Is this the same as a UUID?

No. A standard UUIDv4 is fully random and does not sort by creation time. A KSUID embeds a real timestamp in its first bytes, so ordering two KSUIDs as strings also orders them by time, which is useful for database primary keys and event logs.

Are the generated IDs sent to a server?

No. Generation uses the browser's Web Crypto API (crypto.getRandomValues) and runs entirely on your device. Nothing is transmitted or logged.

Why did decoding fail on my pasted value?

A valid KSUID is exactly 27 characters using only the base62 alphabet: digits 0-9, uppercase A-Z, and lowercase a-z. Extra whitespace, a wrong length, or characters outside that set will fail decoding.

How precise is the embedded timestamp?

KSUID timestamps have 1-second resolution, not milliseconds. Multiple KSUIDs generated within the same second will decode to the same timestamp but still differ in their random payload.

KSUID Generator

Name: KSUID Generator
Availability: InStock
Author: Nham Vu

Generate one or many KSUIDs, or paste an existing KSUID to see its embedded creation timestamp.

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Decode a KSUID

Generate a KSUID or paste one to decode it

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Summary

Generate one or many KSUIDs, or paste an existing KSUID to see its embedded creation timestamp.

How it works

Click "Generate" to create a new KSUID, or set a quantity and click "Generate Bulk" for a list.
Copy a single ID or copy the whole bulk list at once.
Switch to the Decode panel and paste any 27-character KSUID.
The decoder shows the embedded UTC timestamp, local time, and the random payload in hex.

Use cases

Generate primary keys that sort chronologically by creation time without a database sequence.
Create sample IDs for seeding test data or fixtures.
Find out exactly when a KSUID stored in your database or logs was created.
Compare two KSUIDs to confirm which one was generated first.
Replace UUIDv4 with a sortable, timestamp-carrying identifier for new services.
Verify a third-party library's KSUID output during development.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu