CSP Validator

A Content Security Policy, or CSP, is a security standard that helps protect websites from cross-site scripting and other code injection attacks. It works through an HTTP header that tells the browser which sources of content it can load and execute. The browser then blocks anything that does not match the policy.

But writing a good CSP is not easy. A single mistake can break your site or leave you vulnerable. That is where this CSP validator comes in.

This tool checks your policy for errors and weaknesses. It tells you exactly what is wrong and how to fix it. You do not need to log in or sign up. Just paste your policy or enter a URL, and the tool does the rest.

What this CSP validator tool do-

The validator scans your Content Security Policy and looks for problems. It checks for syntax errors, missing directives, and risky values that weaken your security.

The tool also gives you recommendations. If your policy uses unsafe inline scripts or eval, it will tell you. If you are missing important directives like object src or base uri, it will point that out. You get a clear report with everything you need to make your policy stronger.

You can use the validator in two ways. Paste your policy directly into the tool. Or enter a website URL, and the tool will fetch the CSP from the response headers or meta tags.

Key Features

The CSP validator includes several features that make it useful for developers and site owners.

• Syntax checking. The tool validates every directive and value in your policy. It flags anything that does not follow the CSP specification.
• Semantic analysis. Beyond syntax, the tool looks at the meaning of your policy. It checks if your directives work together properly and if any are missing.
• Risk identification. The validator spots dangerous directives like unsafe inline and unsafe eval. These weaken your protection against XSS attacks.
• Actionable recommendations. You do not just get a list of problems. The tool tells you what to change and why. Each recommendation is specific and practical.
• URL fetching. Enter any URL, and the tool pulls the CSP from that site. This is useful for checking your own live site or studying how other sites configure their policies.
• Policy parsing. The validator breaks down your policy into a clean table of directives and their values. This makes it easy to see exactly what your policy contains.

How to Use the CSP Validator

Using the tool takes just a few steps.

Step 1. Go to the CSP validator page on AntiSpywares.net.

Step 2. Choose your input method. You can paste a policy into the text area. Or you can enter a URL and let the tool fetch the policy for you.

Step 3. Click the Validate CSP button.

Step 4. Review the results. The tool shows errors, warnings, and recommendations. It also displays a parsed version of your policy with each directive listed separately.

Step 5. Make the suggested changes to your policy. Test again if needed.

The whole process takes less than a minute. You can run as many checks as you want. There are no limits or restrictions.

When can you use this tool

You might use the CSP validator in several situations.

• Before deploying a new policy. Test your policy before putting it live. Catch problems early so you do not break your site.
• After making changes. If you update your CSP, run it through the validator. Make sure the changes did not introduce new issues.
• When troubleshooting. If your site behaves strangely after adding a CSP, the validator can help find the cause. It might be a directive that is blocking something important.
• For learning. The tool helps you understand CSP better. By seeing what is wrong and why, you learn how to write better policies.
• For auditing. Check your existing policy against best practices. See if there are gaps you should close.

Frequently Asked Questions

What is a Content Security Policy?

A Content Security Policy is a security header that tells the browser which resources a page can load. It helps prevent cross-site scripting and other injection attacks. The policy uses directives to control scripts, styles, images, fonts, and other content types. For a detailed reference, check the MDN CSP reference.

Why do I need a CSP validator?

Writing a CSP by hand is error prone. A small mistake can break your site or leave it unprotected. A validator catches those mistakes before they cause problems. It also helps you follow security best practices.

What does unsafe inline mean?

Unsafe inline allows the browser to run JavaScript or CSS that is embedded directly in the HTML. This is risky because an attacker who injects code can execute it. Modern CSPs use nonces or hashes instead of unsafe inline.

What does unsafe eval do?

Unsafe eval allows the use of eval and similar functions that execute strings as code. This creates a security risk because an attacker can inject malicious strings. It is better to avoid unsafe eval and use safer alternatives.

Can I test my policy without breaking my site?

Yes. Many sites use report only mode first. This sends CSP violations to a report endpoint but does not block anything. You can test your policy this way before enforcing it. Our validator helps you check the policy itself before you even deploy it.

What is a nonce in CSP?

A nonce is a random number that changes with each request. You add it to script tags and to the CSP header. The browser only runs scripts that have the matching nonce. This allows inline scripts without using unsafe inline.

How does the URL fetch feature work?

The tool sends a request to the URL you provide. It reads the Content Security Policy header from the response. If the header is not present, it looks for a CSP meta tag in the HTML. The tool then validates whatever it finds.

What is the difference between CSP and other security headers?

CSP controls what content the browser can load. Other headers like HSTS enforce HTTPS connections. X Frame Options prevent clickjacking. They work together but do different things. CSP is specifically about controlling resource loading.

Is this tool free to use?

Yes. The CSP validator is completely free. You do not need to create an account or pay anything. Use it as many times as you want.

How accurate is the validator?

The validator follows the CSP Level 3 specification. It checks for known directives and common mistakes. It also includes semantic checks based on security best practices. While no tool is perfect, this validator catches most common issues.

A strong Content Security Policy is one of the best defenses against cross-site scripting and injection attacks. But a weak or broken policy can give you a false sense of security. Use this CSP validator to make sure your policy actually protects your site.

Check your policy today. Find the problems. Fix them. And keep your visitors safe.

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Disclaimer: Results from this tool are provided for informational purposes only. While we strive for accuracy, we cannot guarantee that every result is complete or error-free. Always verify important findings using additional methods before making security, technical, or business decisions.