KSUID Generator - K-Sortable Unique Identifier Online

Last updated March 22, 2026

What is a KSUID?

KSUID (K-Sortable Unique Identifier) is a globally unique identifier that combines a timestamp with random data to create identifiers that are naturally sortable by generation time. Developed by Segment, KSUIDs are used in production by companies like Segment and Stripe for tracking events, orders, and distributed system coordination.

A KSUID is a 20-byte identifier encoded as a 27-character Base62 string. The first 4 bytes represent a Unix timestamp in seconds, and the remaining 16 bytes are cryptographically random. This structure ensures KSUIDs are globally unique, naturally ordered by creation time, and human-readable enough to be used in logs and debugging.

KSUID Structure

A KSUID consists of two parts:

• Timestamp (32 bits): Unix timestamp in seconds since a custom epoch (2014-05-13T16:53:20Z), providing natural chronological sorting
• Payload (128 bits): Cryptographically random bytes ensuring uniqueness even when generated at the same second
• Encoding: Base62 (0-9, A-Z, a-z) for URL-safety and readability

Why Use KSUID?

KSUIDs offer several advantages for distributed systems:

• Sortable: Natural chronological ordering without additional timestamp fields
• Unique: 128 bits of randomness ensure global uniqueness
• Readable: Base62 encoding is more human-friendly than hex
• Compact: 27 characters vs 36 for UUID
• Timestamp-aware: Extract creation time from the ID itself
• Production-proven: Used by major companies in high-scale systems

KSUID vs Other IDs

How to Use KSUID Generator

Step 1: Choose Quantity

Enter the number of KSUIDs you need in the quantity field (1-1000). For most applications, generating 5-10 KSUIDs at a time is sufficient for testing and development. Each KSUID is guaranteed to be globally unique and sortable by creation time.

Step 2: Generate KSUIDs

Click the "Generate KSUIDs" button to create your identifiers. Generation happens instantly in your browser using cryptographically secure random number generation. Each KSUID includes a timestamp that shows exactly when it was created, down to the second.

Step 3: View Decoded Information

Each generated KSUID is displayed with its decoded information including the timestamp, date/time in ISO format, and the raw payload. This makes it easy to understand when each ID was created and verify the chronological ordering.

Step 4: Copy or Download

Click any KSUID to copy it to your clipboard, or use the "Download" button to save all generated KSUIDs as a text file. The downloaded file contains one KSUID per line, making it easy to import into your application.

Common Use Cases for KSUID

1. Event Tracking and Analytics

Segment uses KSUIDs for tracking events in their analytics platform. The sortable nature of KSUIDs makes it easy to query events in chronological order without needing a separate timestamp index. This improves query performance and simplifies data modeling for time-series event data.

2. Order and Transaction IDs

Stripe and other payment processors use KSUIDs for order and transaction identifiers. The embedded timestamp makes it easy to find recent transactions, and the global uniqueness ensures no ID collisions across distributed payment processing systems. The human-readable format also helps with customer support and debugging.

3. Distributed Database Primary Keys

KSUIDs make excellent primary keys for distributed databases because they're naturally ordered by creation time, which improves database index performance. Unlike random UUIDs that cause index fragmentation, KSUIDs are always inserted at the end of the index, reducing write amplification and improving performance.

4. Log Aggregation and Tracing

In distributed systems with multiple services generating logs, KSUIDs provide a way to uniquely identify log entries while maintaining chronological order. The embedded timestamp makes it easy to correlate logs across services and trace request flows through the system.

5. Message Queue Identifiers

Message queues and event streaming systems benefit from KSUIDs because messages are naturally ordered by creation time. This makes it easy to process messages in order, implement time-based retention policies, and debug message flow issues by examining the embedded timestamps.

KSUID Examples

Example 1: Go Implementation

package main

import (
    "fmt"
    "github.com/segmentio/ksuid"
)

func main() {
    // Generate a new KSUID
    id := ksuid.New()
    fmt.Println(id.String()) // 0ujtsYcgvSTl8PAuAdqWYSMnLOv
    
    // Get timestamp
    fmt.Println(id.Time()) // 2017-10-09 21:00:47 +0000 UTC
}

Example 2: Node.js Implementation

const KSUID = require('ksuid');

// Generate a new KSUID
const id = KSUID.randomSync();
console.log(id.string); // 0ujtsYcgvSTl8PAuAdqWYSMnLOv

// Parse existing KSUID
const parsed = KSUID.parse('0ujtsYcgvSTl8PAuAdqWYSMnLOv');
console.log(parsed.date); // 2017-10-09T21:00:47.000Z

Example 3: Database Schema (PostgreSQL)

CREATE TABLE events (
    id CHAR(27) PRIMARY KEY,
    user_id VARCHAR(255) NOT NULL,
    event_type VARCHAR(50) NOT NULL,
    data JSONB,
    created_at TIMESTAMP DEFAULT NOW()
);

-- Insert with KSUID
INSERT INTO events (id, user_id, event_type, data) 
VALUES ('0ujtsYcgvSTl8PAuAdqWYSMnLOv', 'user123', 'page_view', '{}');

Example 4: Sorting KSUIDs

const ksuids = [
    '0ujtsYcgvSTl8PAuAdqWYSMnLOv',
    '0ujsszwN8NRY24YaXiTIE2VWDTS',
    '0ujssxh0cECutqzMgbtXSGnjorm'
];

// KSUIDs are naturally sortable
ksuids.sort(); // Already in chronological order!

// Extract timestamps
ksuids.forEach(id => {
    const ksuid = KSUID.parse(id);
    console.log(`${id}: ${ksuid.date}`);
});

Example 5: API Response

{
  "order_id": "0ujtsYcgvSTl8PAuAdqWYSMnLOv",
  "customer_id": "cus_abc123",
  "amount": 4999,
  "currency": "usd",
  "status": "pending",
  "created": 1507584047
}

Frequently Asked Questions

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