CSP Builder is designed for the exact search intent behind “content security policy generator”. Build a Content-Security-Policy header by selecting directives and source expressions, then review the generated policy before deploying it. Build a Content-Security-Policy header by selecting directives and source expressions, then review the generated policy before deploying it. How CSP works CSP restricts which resources a document may load or execute. Directives such as default-src , script-src , style-src , img-src and connect-src govern different resource types. Fallback behavior matters default-src is a fallback for several fetch directives, but not every CSP directive. Adding a more specific directive can replace that fallback for its resource type. Roll out carefully A restrictive policy can break legitimate scripts, styles, fonts, frames or API calls. Test against your actual application and consider report-only deployment during tuning. Worked example: A restrictive baseline might begin with `default-src 'self'`, then add narrowly scoped directives required by the application. Common practical uses include Draft CSP response headers; Audit allowed resource origins; Prepare a report-only policy; Document application security controls. Important limitations: A generated policy cannot discover every resource your application needs. Incorrect CSP can break production functionality. CSP is defense in depth and does not replace output encoding, dependency security or other controls. Key questions this page should answer include: What is Content Security Policy? CSP is a browser security mechanism that restricts permitted sources and behaviors for resources in a document. What does default-src do? It provides a fallback source list for several resource-fetching directives when a more specific directive is absent. What is the difference between CSP and CSP Report-Only? An enforcing policy blocks violations; Report-Only reports violations without enforcing the restrictions. Should I use unsafe-inline? Avoid weakening a policy without understanding the tradeoff; nonce- or hash-based approaches are often preferred for controlled inline code. Can a CSP generator guarantee my site is secure? No. The policy must be tested against the actual application and is only one layer of web security. The page should stay focused on this differentiator: Security-first CSP generation with fallback semantics and report-only rollout, not copy-paste false confidence.
How to use this tool
How CSP works
CSP restricts which resources a document may load or execute. Directives such as default-src, script-src, style-src, img-src and connect-src govern different resource types.
Fallback behavior matters
default-src is a fallback for several fetch directives, but not every CSP directive. Adding a more specific directive can replace that fallback for its resource type.
Roll out carefully
A restrictive policy can break legitimate scripts, styles, fonts, frames or API calls. Test against your actual application and consider report-only deployment during tuning.
Examples
Basic starting policy
A restrictive baseline might begin with `default-src 'self'`, then add narrowly scoped directives required by the application.
Common use cases
- Draft CSP response headers
- Audit allowed resource origins
- Prepare a report-only policy
- Document application security controls
Frequently asked questions
What is Content Security Policy?
CSP is a browser security mechanism that restricts permitted sources and behaviors for resources in a document.
What does default-src do?
It provides a fallback source list for several resource-fetching directives when a more specific directive is absent.
What is the difference between CSP and CSP Report-Only?
An enforcing policy blocks violations; Report-Only reports violations without enforcing the restrictions.
Should I use unsafe-inline?
Avoid weakening a policy without understanding the tradeoff; nonce- or hash-based approaches are often preferred for controlled inline code.
Can a CSP generator guarantee my site is secure?
No. The policy must be tested against the actual application and is only one layer of web security.