Simple Custom CSS and JS is a lightweight yet powerful WordPress plugin that empowers users to inject custom CSS and JavaScript into their websites without altering core theme or plugin files. This plugin is an essential tool for developers and site administrators who require flexibility in styling or scripting, while ensuring a clean and maintainable WordPress environment.

Thanks to its intuitive interface and code editor with syntax highlighting, Simple Custom CSS and JS makes code management straightforward and efficient. Furthermore, the plugin has undergone rigorous security testing and proudly carries the Plugin Security Certification (PSC-2025-64567) issued by CleanTalk, validating its compliance with modern secure coding standards.

Name of	Simple Custom CSS and JS
Version	3.50
Downloads	600 000+
Description	Safely add custom CSS and JavaScript to WordPress without modifying files.
Security	Successfully tested for SQL Injections, XSS Attacks, CSRF Attacks, Authentication Vulnerabilities, Authentication Bypass Vulnerabilities, Privilege Escalation Vulnerabilities, Buffer Overflow Vulnerabilities, Denial-of-Service (DoS) Vulnerabilities, Data Leakage Vulnerabilities, Insecure Dependencies, Code Execution Vulnerabilities, Privilege Escalation Vulnerabilities, File Unauthorized Access Vulnerabilities, Insufficient Injection Protection, and Information Leakage Vulnerabilities.
CleanTalk Certification	Proudly earned the “Plugin Security Certification” (PSC) from CleanTalk, indicating adherence to stringent security standards.
Additional Information	Users can confidently manage age restrictions with the assurance of the “Plugin Security Certification” (PSC). Verify the latest details on the plugin developer’s website.
Plugin Security Certification by CleanTalk
Logo of the plugin

Key Features

1. Built-in Syntax Highlighting Editor
2. Easily write and manage CSS and JavaScript with an intuitive code editor that supports syntax highlighting for better readability and fewer mistakes.
3. Flexible Code Injection Options
4. Insert CSS and JS inline or via external files. Control where the code is loaded—header or footer—to optimize page performance.
5. Frontend & Admin Area Support
6. Add styles or scripts to the public frontend or the WordPress admin dashboard for custom backend experiences.
7. Persistent Across Theme Changes
8. Your customizations remain intact even when switching themes, making it ideal for long-term projects and iterative design.
9. Unlimited Code Snippets
10. Add and manage multiple CSS and JS snippets independently. Each can be toggled on or off and scoped to specific parts of your site.

Security Assurance

Simple Custom CSS and JS prioritizes security by implementing strict input sanitization, validation, and access control mechanisms. All user-defined code is stored and executed under controlled environments to minimize the risk of introducing vulnerabilities such as cross-site scripting (XSS) or code injection.

As part of its commitment to secure development, the plugin has successfully passed a comprehensive source code audit conducted by CleanTalk Security Lab. It has earned the Plugin Security Certification (PSC-2025-64567), confirming its adherence to industry best practices in secure WordPress plugin development.

This certification ensures that:

• Custom code injection is sandboxed and scoped properly
• Admin-only access is enforced for editing code
• Stored code is sanitized and validated to prevent misuse
• No known vulnerabilities were found during security evaluation

The certification demonstrates the plugin developer’s commitment to maintaining a safe WordPress ecosystem and offers peace of mind to users handling sensitive or complex websites.

Conclusion

Simple Custom CSS and JS offers a practical and secure solution for customizing the appearance and functionality of a WordPress site through additional CSS and JavaScript. With its ease of use, flexible configuration, and verified security via the CleanTalk Plugin Security Certification (PSC-2025-64567), it stands as a trustworthy tool for developers and website administrators. Whether you’re fine-tuning your site’s UI or adding interactive scripts, this plugin ensures you can do so confidently and securely.

Note: The date and certification information may change over time. It is advisable to verify the latest details on the plugin developer’s website.