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CSP header generator

Security tools

Build a Content-Security-Policy header from domain allowlists.

Updated

CSP header generator

Build a Content-Security-Policy header from domain allowlists.

Input format: One allowed origin per line

Output

Quick start

How to use csp-header-generator

Enter input and view computed output.

  1. Step 1
    Enter input

    Paste or type your data in the input box.

  2. Step 2
    Compute

    The tool processes input instantly in your browser.

  3. Step 3
    Use output

    Copy output and continue your workflow.

In-depth guide

CSP header generator guide

Build a Content-Security-Policy header from domain allowlists. This tool is designed for fast local processing and practical day-to-day use.

Quick start

Paste input, review output instantly, then copy it for your workflow.

Input tips

Use one value per line for structured inputs. Common separators are handled gracefully.

Privacy

Processing runs in your browser tab for the MVP workflow, with no mandatory upload step.

When to use it vs alternatives

Use this tool for quick browser-based work when you need an answer or output immediately. Use a dedicated application or automated workflow when you need bulk processing, approvals, or repeatable production rules.

Common pitfalls

  • Check the result before replacing the original input.
  • Watch for unit, format, encoding, and browser memory limits on large inputs.
  • Keep a copy of important source material until the output is verified.

Frequently asked questions

What is a Content-Security-Policy header?

It tells the browser which sources of scripts, styles, images and other resources are allowed, which mitigates cross-site scripting and data injection attacks.

How do I start without breaking my site?

Deploy the policy in report-only mode first using Content-Security-Policy-Report-Only, watch the violation reports, then enforce once it is clean.

Why is unsafe-inline discouraged?

Allowing unsafe-inline defeats much of CSP's XSS protection. Prefer nonces or hashes for the few inline scripts and styles you genuinely need.

What does default-src do?

It is the fallback for any directive you do not set explicitly, so a restrictive default-src plus targeted overrides is a solid baseline.

Where do I put the header?

Send it as an HTTP response header from your server or CDN. A meta tag works for some directives but cannot cover frame-ancestors or sandbox.

Is anything uploaded?

No. The header string is generated entirely in your browser.

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