14 best Anti-spam libraries in 2025

Anti-spam libraries are used by developers to build their own anti-spam tools. They are open-source and available for free.

They can be easily integrated into an application or website to help keep it clean from spammers. The anti-spam libraries are used to detect spam links. They work by checking whether a link is on a spam list or performing other checks, such as checking if the link is a shortened URL. Invisible_captcha is a library that can be used to create a CAPTCHA using images that are impossible to read by humans but easy for computers. The code is available on GitHub, and there are several examples on the website. Friendly-challenge is another anti-spam library that does the same thing as invisible_captcha but has a few more features, such as multiple image sizes, custom background colors, and more. Discord Anti-Spam is an anti-spam bot for Discord servers that will prevent unwanted messages from being sent to your server. It works by allowing users to send a message with a link that's posted on a certain channel. If someone clicks on the link within 10 seconds, then the message will be delivered normally; otherwise, it'll be blocked by Discord Anti-Spam. There are several popular open source Anti-spam libraries available for developers

invisible_captcha

• It creates CAPTCHAs with images only understood by computers. 
• The free GitHub code helps put together and spot spam links by using picture challenges. 
•  Identifies spam links by utilizing image-based challenges. 

friendly-challenge

• Combats spam through customizable attributes like diverse image dimensions.  
• Accessible on GitHub as open source, simplifying integration into applications.  
• Enhances adaptability in anti-spam strategies for improved effectiveness.  

discord-anti-Spam

• Secures Discord servers by preventing unwanted messages and validating links. 
•  It implements a 10-second link validation to deter spam.  
• The GitHub repository facilitates straightforward integration, ensuring secure communication on Discord.  

Raid-Protect-Discord-Bot

• Secures servers from large-scale attacks with specialized bot capabilities. 
•  Open-source code on GitHub, available for enhanced server protection. 
•  Delivers strong protection against significant disruptions and threats. 

sweetiebot

• Discord bot with anti-spam and moderation capabilities, available as open source. 
•  Accessible on GitHub for convenient integration and customization.  
• Ensures a tidy and secure Discord environment through advanced features.  

Discord-Anti-Spam

• Prevents unwanted messages and verifies links to enhance Discord server security. 
•  Effective spam prevention through a 10-second link validation process.  
• GitHub hosts open-source code, facilitating straightforward integration and customization. 

the_viking

• Uses open-source tools to protect against spam and unwanted activities.  
• Improves server security by allowing customization of anti-spam features.  
• To create a smooth and steady on-line environment. 

postfwd-anti-geoip-spam-plugin

• Protects against spam based on geographical location using postfwd. 
•  Adds an extra layer of defense by filtering spam based on IP location.  
• An open-source solution for enhanced anti-spam measures. 

SpamProtectionRobot

•  A dedicated bot prevents spam and ensures a spam-free environment. 
•  Reliable solution for maintaining a clean and secure online space. 
•  Open source for easy integration and customizable settings.  

spamfightbot

• Open-source bot focused on preventing spam with customizable features.  
• Reliable solution for maintaining spam-free environments.  
• GitHub-hosted for easy integration and customization. 

FluffyProtect

•  Defends servers against spam with tailored and customizable features.  
• GitHub-hosted open-source code ensures easy integration.  
• Enhances server security and prevents unwanted disruptions. 

YOURLS-Phishtank-2.0

•  Counters spam and phishing attacks on YOURLS link shortener.  
• Enhances link security with effective anti-spam features.  
• Open-source solution for secure URL shortening.  

plg_captcha_friendlycaptcha

•  Utilizes Friendly Captcha for effective and secure anti-spam measures. 
•  Open-source and customizable approach for secure forms. 
•  Enhances security by ensuring genuine user interactions.  

milter

• Milter plugin enhances email server security with anti-spam measures.  
• Adds a layer of protection by filtering spam at the mail server level.  
• Open source for easy integration and efficient spam prevention.  

FAQ

1. Why do developers use anti-spam libraries?  

Developers use anti-spam libraries to create tools that prevent spam, maintaining clean applications.  

2. Are anti-spam libraries free and accessible?  

Yes, these libraries are open-source and available for free, ensuring easy integration.  

3. How do these libraries detect spam links?  

They check links against spam lists and perform checks like identifying shortened URLs.  

4. What sets Friendly-challenge apart from Invisible_captcha? 

 Friendly Challenge offers extra features, including many image sizes and custom background colors.

5. How does Discord Anti-Spam prevent unwanted messages on servers? 

 Discord Anti-Spam stops messages if the linked content isn't clicked within 10 seconds. This happens in a specific channel.