Content Security Policy

Content Security Policy (CSP) is a security standard that helps prevent cross-site scripting (XSS), clickjacking, and other code injection attacks by allowing web developers to control which resources (such as scripts, styles, images, or fonts) a browser is allowed to load for a given page. It is implemented via HTTP response headers that specify allowed sources for different types of content, effectively creating a whitelist of trusted origins. This reduces the risk of malicious content execution by restricting where resources can be fetched from.

Also known as: CSP, Content-Security-Policy, CSP Headers, Content Security Policy Headers, Security Policy Headers

Why learn Content Security Policy?

Developers should learn and implement CSP when building web applications that handle sensitive user data or require high security, such as banking sites, e-commerce platforms, or any service vulnerable to XSS attacks. It is particularly useful in modern web development where third-party scripts and APIs are common, as it provides granular control over resource loading to mitigate injection vulnerabilities. Implementing CSP headers is a best practice for enhancing web application security and is often required for compliance with standards like OWASP Top 10.

Learning Resources

• docs: MDN Web Docs: Content Security Policy (CSP)
• tutorial: Google Web Fundamentals: Content Security Policy
• docs: OWASP Cheat Sheet Series: Content Security Policy
• tool: CSP Evaluator by Google
• video: YouTube: Introduction to Content Security Policy