CUID (Collision-resistant Unique IDentifier)

0.4 · deprecated · verified Sun Apr 12

cuid.py is a Python implementation of the original CUID (Collision-resistant Unique IDentifier) standard, designed for horizontally scalable and fast unique ID generation. It aims to provide portable and sequentially-ordered unique identifiers. The current version is 0.4. The upstream CUID standard (v1), which this library implements, has been deprecated in favor of CUID2 due to security considerations, so this library is not actively developed beyond maintenance for the deprecated standard.

Warnings

breaking The original CUID standard (v1), implemented by this library, has been officially deprecated upstream due to security concerns. It leaks timestamps and other potentially predictable information, making it unsuitable for security-sensitive applications where IDs should not be guessable or reveal creation order. The successor is CUID2.
Fix: For new projects or security-sensitive applications, consider migrating to `cuid2` (a separate Python package implementing CUID2) or another ID generation scheme that offers stronger security guarantees. The `cuid2` library offers similar benefits (collision resistance, scalability) with enhanced security.
deprecated This Python library implements the deprecated CUID v1 standard. While functional, it is no longer recommended for new development, especially where security or information leakage are concerns. The project appears to be in maintenance mode for this deprecated standard.
Fix: Evaluate whether your use case truly requires CUID v1 characteristics. If not, switch to `cuid2` for improved security. If bound to CUID v1, be aware of its limitations and deprecation status.
gotcha The `cuid.slug()` function generates shorter, URL-friendly identifiers. However, slugs have less random data, less room for the counter and fingerprint, which increases the probability of collisions. They are explicitly NOT recommended for use as database unique IDs or primary keys where strong collision resistance is critical.
Fix: Only use `cuid.slug()` for non-critical, human-readable identifiers such as URL slugs. Always use the full `cuid.cuid()` for database primary keys or other scenarios requiring high collision resistance.
gotcha CUIDs, including those generated by `cuid.py`, are string-based identifiers. When used as database primary keys, ensure that database columns are appropriately indexed for optimal performance. They are not intrinsically integers and may not perform as well with auto-incrementing integer primary key optimizations in some databases.
Fix: Ensure database columns storing CUIDs are properly indexed as strings/text. If strict sequential (gap-less) numbers or extremely small storage footprints are critical, consider auto-incrementing integers or other ID types, respectively.

Install

pip install cuid Install stable version

Imports

cuid
```
import cuid
```
While 'from cuid import cuid' works, it can lead to confusion if you also use 'cuid.slug()'. Importing the module directly and accessing functions via 'cuid.cuid()' or 'cuid.slug()' is clearer.

Quickstart

Demonstrates how to generate a standard CUID and a shorter CUID slug using the library. Note the warning about slugs for primary keys.

import cuid

# Generate a standard CUID
my_cuid = cuid.cuid()
print(f"Generated CUID: {my_cuid}")

# Generate a 'slug' (shorter, less collision-resistant, not for primary keys)
my_slug = cuid.slug()
print(f"Generated CUID slug: {my_slug}")

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