Antispam Link Shorteners 🛡️

A lightweight, zero-dependency, ultra-fast Python library designed to detect and block malicious or spam URL shortener domains using a curated blocklist.

This package provides a reliable way to check if an arbitrary URL or domain string belongs to a known link shortener ( such as bit.ly, t.co, tinyurl.com). It helps developers protect their platforms from re-linking spam, malicious redirects, chain shortening, and automated bot activities.

Key Benefits

• High Performance: The blocklist is parsed and loaded into an in-memory set upon the first call, cached seamlessly via functools.lru_cache. Subsequent checks require zero disk I/O overhead providing immediate $O(1)$ lookups.
• Smart Input Normalization: Transparently strips whitespace, ignores casing, drops www. prefixes, and securely handles both absolute URLs (with protocols) and naked domain variants.

📦 Installation

Install the package via pip or using uv:

# Using standard pip
pip install antispam-link-shorteners

# Using uv (Recommended)
uv add antispam-link-shorteners

🚀 Usage

The library exposes two main public functions: is_link_shortener and link_shorteners_list.

1. Checking a URL (is_link_shortener)

The is_link_shortener() function takes an incoming string, normalizes it, runs security validation checks, and returns a boolean indicating whether the core domain is a known shortener.

from antispam_link_shorteners import is_link_shortener

# Handled successfully across various input layouts:
print(is_link_shortener("bit.ly"))  # True
print(is_link_shortener("  BIT.LY  "))  # True (casing & whitespace)
print(is_link_shortener("www.bit.ly"))  # True (www stripping)
print(is_link_shortener("[https://www.bit.ly/abc?p=1](https://www.bit.ly/abc?p=1)"))  # True (path/query parsing)

# Legitimate domains pass through:
print(is_link_shortener("https://github.com"))  # False

Exception Handling & Security Guardrails

is_link_shortener() explicitly protects execution workflows by enforcing strict data structural criteria:

from antispam_link_shorteners import is_link_shortener

try:
    is_link_shortener(12345)  # TypeError
except TypeError:
    ...

try:
    is_link_shortener("   ")  # ValueError
except ValueError:
    ...

try:
    is_link_shortener("www.ggaaa")  # ValueError
except ValueError:
    ...

2. Fetching the Underlying Raw List (link_shorteners_list)

Use link_shorteners_list() to interact directly with the underlying cached set of clean, lowercase blacklisted domains:

from antispam_link_shorteners import link_shorteners_list

banned_set = link_shorteners_list()
print(type(banned_set))  # <class 'set'>
print("tinyurl.com" in banned_set)  # True (O(1) memory lookup)

👥 Credits & Attribution

This library relies on the following open-source resources:

1. Data Source: The domain blocklist text file is directly sourced from the PeterDaveHello/url-shorteners.
2. Original Project: This project represents a heavily refactored, type-hinted, performance-optimized, and modernized Python alternative inspired by mayakyler/link-shorteners.

⚖️ License

This project uses a multi-license structure to cleanly respect all upstream authors:

• Modified library: Licensed under the MIT License.
• Original library: Licensed under the MIT License.
• Blocklist Dataset: Distributed under the Creative Commons Attribution-ShareAlike 4.0 International License ( CC-BY-SA-4.0).