In-Browser Content Security Policy (CSP) Builder & Evaluator
XSS DefenseConstruct, evaluate, and test Content-Security-Policy (CSP) headers directly inside your browser. This interactive security builder lets you configure fetch directives, audit policy configurations against OWASP XSS standards, and generate production snippets for Nginx, Apache, HTML meta tags, and Next.js applications.
Content Security Policy (CSP) Builder & Evaluator
Build, evaluate, and test Content-Security-Policy headers with real-time XSS security grading and server snippets.
Interactive Content Security Policy (CSP) Builder & Evaluator Workspace
Construct, evaluate, and test Content-Security-Policy (CSP) headers directly inside your browser. This interactive security builder lets you configure fetch directives, audit policy configurations against OWASP XSS standards, and generate production snippets for Nginx, Apache, HTML meta tags, and Next.js applications.
How This Tool Works (100% Client-Side Engine)
The tool parses user-selected source tokens and custom domain strings into compliant CSP Level 3 directives. The real-time evaluation engine inspects the directive tree against established OWASP guidelines, checking for unsafe-inline, unsafe-eval, broad wildcards, and missing base-uri defenses to calculate a standardized security grade.
Step-by-Step Guide
Choose a Baseline Preset or Import
Select Strict Zero-Trust, Modern Web, or Single Page App preset, or paste an existing CSP header string to load your configuration.
Customize Fetch Directives & Allowed Hosts
Toggle source pills (self, data:, https:) or add your specific CDN and API domains to directives like script-src, style-src, and img-src.
Review Audit Score & Copy Server Snippets
Check your real-time security grade and copy the ready-to-use configuration for Nginx, Apache .htaccess, HTML meta tags, or Next.js.
Why Use This Tool: Privacy & Performance
Crafting Content Security Policy headers manually is error-prone. A single misconfigured directive can either fail to protect against cross-site scripting (XSS) or completely break legitimate third-party analytics, web fonts, and API requests. Furthermore, testing security policies on third-party remote generators can inadvertently expose internal subdomains, proprietary microservice endpoints, and staging architecture to external servers. ToolByte solves this with a 100% in-browser CSP workspace. All directive synthesis, syntax validation, and heuristic vulnerability scoring execute locally in your physical browser memory. You can visually adjust sources, review automated risk assessments for unsafe-inline or broad wildcards, and instantly copy hardened server headers. Zero policy parameters or hostnames are ever transmitted over the network, ensuring absolute confidentiality for your web security infrastructure.
Common Use Cases & Workflows
Mitigating Cross-Site Scripting (XSS) on Production Apps
Enforce strict script-src and default-src whitelists to ensure injected script tags and malicious DOM modifications are rejected by modern browsers.
Defending Against UI Clickjacking & Iframe Hijacking
Configure frame-ancestors to prevent malicious third-party websites from embedding your authenticated web application inside transparent iframes.
Meeting PCI-DSS & SOC 2 Compliance Requirements
Generate standardized, auditable HTTP security headers and eliminate legacy object-src plugins to satisfy enterprise compliance audits.
Safely Staging CSP Policies in Report-Only Mode
Test new restrictive security policies on live production traffic with Content-Security-Policy-Report-Only without breaking UI functionality.
Technical Limitations & Operational Boundaries
Frequently Asked Questions
Recommended Utilities Complementary to CSP Header Builder
High-performance tools running 100% in local browser memory with zero server data retention.