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KSUID - K-Sortable Unique Identifier

PyPI version Python Version License: MIT Downloads

A Python implementation of KSUID (K-Sortable Unique Identifier) for Python 3.13+.

What is a KSUID?

A KSUID is a globally unique identifier similar to a UUID, but with better properties:

  • Sortable: KSUIDs are naturally sortable by creation time
  • Compact: 27 characters when base62-encoded (vs 36 for UUID)
  • URL-safe: Uses base62 encoding (no special characters)
  • Collision-resistant: 128 bits of randomness per millisecond
  • Time-based: Encodes creation timestamp for easy debugging
  • Prefix-friendly: Can be prefixed for type identification (like Stripe's API keys)

Format

A KSUID is a 20-byte identifier consisting of:

  • 4 bytes: Timestamp (seconds since KSUID epoch: 2014-05-13 16:53:20 UTC)
  • 16 bytes: Random payload

When base62-encoded, it becomes a 27-character string like: 2StGMtcWzRJ8qZqQjbJjGdTkVfv

Real-World Usage Examples

Many successful companies use KSUID-style identifiers with prefixes for better developer experience:

Stripe-Style Prefixed IDs

from ksuid import generate

# Payment Intent: pi_1A2B3C...
payment_intent = f"pi_{generate()}"

# Customer: cus_1A2B3C...
customer = f"cus_{generate()}"

# Charge: ch_1A2B3C...
charge = f"ch_{generate()}"

GitHub-Style IDs

# Repository: repo_1A2B3C...
repository = f"repo_{generate()}"

# Issue: issue_1A2B3C...
issue = f"issue_{generate()}"

# Pull Request: pr_1A2B3C...
pull_request = f"pr_{generate()}"

Database Entity IDs

# User: user_1A2B3C...
user_id = f"user_{generate()}"

# Order: order_1A2B3C...
order_id = f"order_{generate()}"

# Product: prod_1A2B3C...
product_id = f"prod_{generate()}"

Benefits of Prefixed KSUIDs

  1. Type Safety: Immediately identify the entity type
  2. Debugging: Easier to trace issues in logs
  3. API Design: Self-documenting API endpoints
  4. Database Queries: Faster filtering by prefix
  5. Developer Experience: Clear, readable identifiers

Installation

Install from PyPI:

pip install ksuid-python

Note: The package name is ksuid-python, but you import it as ksuid:

from ksuid import generate  # Import name is 'ksuid'

Quick Start

from ksuid import KSUID, generate

# Generate a new KSUID
ksuid = generate()
print(ksuid)  # 2StGMtcWzRJ8qZqQjbJjGdTkVfv

# Create from string
ksuid2 = KSUID.from_string('2StGMtcWzRJ8qZqQjbJjGdTkVfv')

# KSUIDs are sortable
ksuid1 = generate()
time.sleep(0.001)
ksuid2 = generate()
assert ksuid1 < ksuid2  # True!

# Access timestamp and payload
print(ksuid.datetime)  # 2025-01-17 10:30:45+00:00
print(ksuid.timestamp)  # 1737108645
print(len(ksuid.payload))  # 16 bytes

API Reference

Class: KSUID

Constructor

KSUID(timestamp=None, payload=None)
  • timestamp: Unix timestamp (int). If None, uses current time.
  • payload: 16-byte random payload (bytes). If None, generates random bytes.

Class Methods

KSUID.from_string(ksuid_str: str) -> KSUID

Create a KSUID from its base62 string representation.

KSUID.from_bytes(data: bytes) -> KSUID

Create a KSUID from raw 20-byte data.

Properties

  • timestamp: Unix timestamp (int)
  • datetime: Python datetime object (UTC)
  • payload: 16-byte random payload (bytes)
  • bytes: Raw 20-byte KSUID data (bytes)

Methods

  • __str__(): Returns base62-encoded string representation
  • __repr__(): Returns developer-friendly representation
  • Comparison operators: <, <=, >, >=, ==, !=
  • __hash__(): Makes KSUIDs hashable (usable in sets/dicts)

Convenience Functions

generate() -> KSUID

Generate a new KSUID with current timestamp.

from_string(ksuid_str: str) -> KSUID

Create KSUID from string (alias for KSUID.from_string).

from_bytes(data: bytes) -> KSUID

Create KSUID from bytes (alias for KSUID.from_bytes).

Examples

Basic Usage

from ksuid import KSUID, generate
import time

# Generate KSUIDs
ksuid1 = generate()
time.sleep(0.001)
ksuid2 = generate()

print(f"KSUID 1: {ksuid1}")
print(f"KSUID 2: {ksuid2}")
print(f"KSUID 1 < KSUID 2: {ksuid1 < ksuid2}")  # True

Prefixed IDs (Stripe-Style)

from ksuid import generate

def create_prefixed_id(prefix: str) -> str:
    """Create a prefixed ID like Stripe's API keys."""
    return f"{prefix}_{generate()}"

# Create different entity types
user_id = create_prefixed_id("user")        # user_2StGMtcWzRJ8qZqQjbJjGdTkVfv
payment_id = create_prefixed_id("pi")       # pi_2StGMtcWzRJ8qZqQjbJjGdTkVfv
customer_id = create_prefixed_id("cus")     # cus_2StGMtcWzRJ8qZqQjbJjGdTkVfv

print(f"User ID: {user_id}")
print(f"Payment ID: {payment_id}")
print(f"Customer ID: {customer_id}")

# Extract KSUID from prefixed ID
def extract_ksuid(prefixed_id: str) -> str:
    """Extract KSUID from prefixed ID."""
    return prefixed_id.split('_', 1)[1]

ksuid_part = extract_ksuid(user_id)
print(f"Extracted KSUID: {ksuid_part}")

Custom Timestamp and Payload

from ksuid import KSUID
from datetime import datetime

# Create with specific timestamp
timestamp = int(datetime(2021, 1, 1).timestamp())
ksuid = KSUID(timestamp=timestamp)

# Create with custom payload
payload = b'\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10'
ksuid = KSUID(payload=payload)

Sorting and Comparison

from ksuid import generate
import time

# Generate multiple KSUIDs
ksuids = []
for i in range(5):
    ksuids.append(generate())
    time.sleep(0.001)

# They're naturally sorted by creation time
sorted_ksuids = sorted(ksuids)
assert ksuids == sorted_ksuids  # True!

# Use in data structures
ksuid_set = set(ksuids)
ksuid_dict = {k: f"value_{i}" for i, k in enumerate(ksuids)}

Database Usage

from ksuid import generate
import sqlite3

# Create table with KSUID primary key
conn = sqlite3.connect(':memory:')
conn.execute('''
    CREATE TABLE users (
        id TEXT PRIMARY KEY,
        name TEXT,
        created_at DATETIME
    )
''')

# Insert records with KSUID
ksuid = generate()
conn.execute(
    'INSERT INTO users (id, name, created_at) VALUES (?, ?, ?)',
    (str(ksuid), 'John Doe', ksuid.datetime)
)

# Query by KSUID
cursor = conn.execute('SELECT * FROM users WHERE id = ?', (str(ksuid),))
print(cursor.fetchone())

Production API Example (Flask)

from flask import Flask, jsonify, request
from ksuid import generate
import sqlite3

app = Flask(__name__)

def create_prefixed_id(prefix: str) -> str:
    return f"{prefix}_{generate()}"

@app.route('/api/users', methods=['POST'])
def create_user():
    data = request.json
    user_id = create_prefixed_id("user")
    
    # Store in database
    conn = sqlite3.connect('app.db')
    conn.execute(
        'INSERT INTO users (id, name, email) VALUES (?, ?, ?)',
        (user_id, data['name'], data['email'])
    )
    conn.commit()
    conn.close()
    
    return jsonify({
        'id': user_id,
        'name': data['name'],
        'email': data['email']
    }), 201

@app.route('/api/users/<user_id>')
def get_user(user_id):
    # Validate prefix
    if not user_id.startswith('user_'):
        return jsonify({'error': 'Invalid user ID format'}), 400
    
    conn = sqlite3.connect('app.db')
    cursor = conn.execute('SELECT * FROM users WHERE id = ?', (user_id,))
    user = cursor.fetchone()
    conn.close()
    
    if not user:
        return jsonify({'error': 'User not found'}), 404
    
    return jsonify({
        'id': user[0],
        'name': user[1],
        'email': user[2]
    })

# Example usage:
# POST /api/users -> {"id": "user_2StGMtcWzRJ8qZqQjbJjGdTkVfv", ...}
# GET /api/users/user_2StGMtcWzRJ8qZqQjbJjGdTkVfv -> User details

Converting Between Formats

from ksuid import KSUID

# Start with a KSUID
ksuid = KSUID()

# Get different representations
string_repr = str(ksuid)           # Base62 string
bytes_repr = ksuid.bytes           # Raw bytes
timestamp = ksuid.timestamp        # Unix timestamp
datetime_obj = ksuid.datetime      # Python datetime

# Recreate from representations
ksuid_from_string = KSUID.from_string(string_repr)
ksuid_from_bytes = KSUID.from_bytes(bytes_repr)

# All should be equal
assert ksuid == ksuid_from_string == ksuid_from_bytes

Performance

KSUIDs are designed to be fast and efficient:

  • Generation: ~1-2 microseconds per KSUID
  • Parsing: ~500 nanoseconds from string
  • Comparison: ~100 nanoseconds
  • Memory: 20 bytes per KSUID + Python object overhead

Comparison with UUIDs

Feature KSUID UUID v4 UUID v1 Stripe IDs
Length 27 chars 36 chars 36 chars 24-28 chars
Sortable ✅ Yes ❌ No ⚠️ Partially ❌ No
URL-safe ✅ Yes ❌ No (hyphens) ❌ No (hyphens) ✅ Yes
Timestamp ✅ Readable ❌ No ✅ But complex ❌ No
Collision resistance ✅ High ✅ High ✅ High ✅ High
Monotonic ✅ Yes ❌ No ⚠️ Partially ❌ No
Prefix support ✅ Natural ❌ Awkward ❌ Awkward ✅ Built-in
Developer UX ✅ Excellent ⚠️ Good ⚠️ Good ✅ Excellent

Industry Adoption & Best Practices

Companies Using KSUID-Style IDs

Many successful companies use sortable, prefixed identifiers:

  • Stripe: pi_1A2B3C..., cus_1A2B3C..., ch_1A2B3C...
  • GitHub: Repository and issue IDs with chronological ordering
  • Slack: Channel and message IDs for efficient sorting
  • Discord: Snowflake IDs (similar concept with timestamps)
  • Twitter: Tweet IDs (chronologically sortable)

Prefix Naming Conventions

Common patterns for prefixes:

# Entity types (3-4 chars)
user_id = f"user_{generate()}"      # Users
prod_id = f"prod_{generate()}"      # Products
ord_id = f"ord_{generate()}"        # Orders

# Action types (2-3 chars)
payment_id = f"pi_{generate()}"     # Payment Intent (Stripe style)
charge_id = f"ch_{generate()}"      # Charge
refund_id = f"re_{generate()}"      # Refund

# Short codes (2-3 chars)
api_key = f"sk_{generate()}"        # Secret Key
pub_key = f"pk_{generate()}"        # Public Key
token = f"tok_{generate()}"         # Token

Database Design Tips

-- Index on prefix for fast filtering
CREATE INDEX idx_users_by_type ON transactions(id) WHERE id LIKE 'user_%';

-- Partial indexes for different entity types
CREATE INDEX idx_payments ON transactions(id) WHERE id LIKE 'pi_%';
CREATE INDEX idx_refunds ON transactions(id) WHERE id LIKE 're_%';

API Design Patterns

# RESTful endpoints with typed IDs
GET /api/users/user_2StGMtcWzRJ8qZqQjbJjGdTkVfv
GET /api/payments/pi_2StGMtcWzRJ8qZqQjbJjGdTkVfv
GET /api/orders/ord_2StGMtcWzRJ8qZqQjbJjGdTkVfv

# Validation middleware
def validate_entity_id(entity_type, entity_id):
    if not entity_id.startswith(f"{entity_type}_"):
        raise ValueError(f"Invalid {entity_type} ID format")
    return entity_id.split('_', 1)[1]  # Return KSUID part

Thread Safety

The KSUID library is thread-safe. Multiple threads can generate KSUIDs concurrently without coordination.

Requirements

  • Python 3.13 or later
  • No external dependencies

Development

# Clone repository
git clone https://github.com/tonyzorin/ksuid-python.git
cd ksuid-python

# Install development dependencies
pip install -e ".[dev]"

# Run tests
pytest

# Run tests with coverage
pytest --cov=ksuid

# Format code
black .

# Type checking
mypy ksuid/

License

MIT License. See LICENSE for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

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