Why is CSP important?

Without a CSP in place, injected JavaScript can steal cookies and tokens, send data to attacker-controlled servers, rewrite the DOM, and perform any action the logged-in user can perform. A reasonable CSP shuts down most of those attacks by restricting where scripts can come from. PCI DSS effectively requires it, OWASP recommends it, and the cost-benefit tradeoff is heavily on the side of having one.

What are common CSP directives?

The directives you'll touch most often are default-src as the fallback for everything, script-src for JavaScript, style-src for CSS, img-src for images, font-src for fonts, connect-src for XHR and WebSocket calls, frame-src for iframes, media-src for audio and video, and object-src for legacy plugins (which you almost certainly want set to 'none'). Each directive lists the sources that resource type can load from.

What is 'unsafe-inline'?

It's the keyword that lets the page execute inline JavaScript (onclick attributes, script blocks with code in them) and apply inline styles. Adding it effectively undoes most of the protection a CSP buys you, because any injected script tag is now allowed to run. Avoid it where you possibly can — the right answer is usually to move the inline code into external files, and if you genuinely cannot, fall back to nonces or hashes for the specific blocks that need to stay inline.

How do I handle inline scripts?

There are three reasonable options. The cleanest is to move the inline code into separate files, where the standard 'self' source covers it. The next best is per-request nonces — your script-src directive gets a 'nonce-abc123' value, and each script tag in the rendered HTML gets a matching nonce attribute generated server-side. The third is SHA-256 hashes of specific known inline blocks, listed in script-src. The last resort is 'unsafe-inline', which is a real security regression and should be a temporary measure rather than a permanent state.

What is report-only mode?

The Content-Security-Policy-Report-Only header tells the browser to log violations to your reporting endpoint without actually blocking anything. It's exactly what you want when rolling out a new policy — you can run it against real production traffic for a week or two, watch for surprises (an inline handler nobody remembered, a CDN that quietly moved domains), and only flip to enforcing the policy once the report stream is quiet.

Can CSP block extensions or user scripts?

It cannot, by design. Browser extensions and user scripts run at a higher privilege level than page scripts and explicitly bypass CSP. The intent is that users control what runs in their own browser — your site's policy governs your own code, not customizations the user has chosen to install. So password managers, ad blockers, and Tampermonkey scripts will keep working regardless of what your CSP says.

How do I test CSP without breaking my site?

Start with the Content-Security-Policy-Report-Only header rather than the enforcing one. Wire up a violation reporting endpoint, leave it running against real production traffic for a week or two while you watch the reports, and use that period to find and fix anything unexpected. Once the report stream is quiet, switch the header to the enforcing form. Roll the change out to staging first and only flip production after staging has been clean for a few days.

CSP Header Generator | Treasure Tools

How to Use CSP Header Generator

Choose policy strictness

Start from a template that matches the posture you want — strict if you can tolerate breaking features in exchange for maximum security, balanced for sensible defaults, permissive when you need to allow a lot of third-party content. Building from scratch is also fine if you already know exactly what you want, but a template is usually a faster path to a defensible baseline.

Add allowed sources per directive

Walk through each directive — script-src, style-src, img-src, connect-src, and so on — and list the sources that resource type can come from. 'self' covers your own origin, specific URLs name the third parties you're consciously approving (CDNs, analytics, payment SDKs), and the resulting policy doubles as a documented allowlist of every external dependency the page actually relies on.

Configure inline handling

Pick how you'll deal with inline scripts and styles. The cleanest option is to refactor them out into separate files. The next best is per-request nonces. Hashes work for specific known inline blocks. The 'unsafe-inline' fallback should be a last resort — it effectively undoes most of what your CSP buys you, and treating it as a temporary measure rather than a permanent state will keep you honest.

Test in report-only mode

Deploy the Content-Security-Policy-Report-Only header first rather than the enforcing one. Wire up a report-uri or report-to endpoint, leave it running against real production traffic for a week or two, and watch the stream for surprises — a forgotten inline handler, a CDN that quietly moved domains. Fix what you find, then flip the header to the enforcing form once the report stream goes quiet.

When to Use CSP Header Generator

XSS defense in depth

A good Content Security Policy is one of the strongest mitigations you have against cross-site scripting. Even if an attacker manages to inject a script tag through a sanitization gap, the browser refuses to execute it unless the source matches your policy. That kind of belt-and-braces protection matters most for financial apps, healthcare portals, and anything handling personal data.

Mixed content prevention

An HTTPS site that quietly pulls a script or image over plain HTTP is a man-in-the-middle waiting to happen. CSP gives you upgrade-insecure-requests to silently rewrite those URLs and block-all-mixed-content to refuse them outright, which makes HTTPS migrations and ongoing hardening much less of a whack-a-mole exercise.

Compliance requirements

Frameworks like PCI DSS, HIPAA, and SOC 2 expect a documented CSP, and pen test reports almost always flag its absence. Generating a baseline header and iterating from there is a faster path to a clean audit than starting from a blank page or hoping a generic example fits your stack.

Third-party content control

Modern apps load a long list of third parties — CDNs, analytics, payment widgets, font providers — and CSP is how you turn that into an explicit allow-list. SaaS products with several integrations especially benefit from spelling out exactly which domains are trusted, since adding a new vendor accidentally becomes harder when the policy is right there in the response headers.

CSP Header Generator Examples

Strict baseline

Input

Strict CSP: only same-origin scripts and styles

Output

Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self'; img-src 'self' data:; font-src 'self'

This is about as locked-down as you can get without going to a nonce-based policy. Everything has to come from your own origin, inline JavaScript and external stylesheets are blocked outright, and data: URIs are allowed only for images. It will break most analytics and CDN-hosted scripts on day one, but that's exactly the point — start strict and add explicit exceptions for things you actually need.

Common third-party allow

Input

Allow Google Analytics, jsdelivr CDN, Stripe

Output

Content-Security-Policy: default-src 'self'; script-src 'self' https://www.google-analytics.com https://cdn.jsdelivr.net https://js.stripe.com; ...

This is closer to what real production CSPs look like. Each external domain is named explicitly, so analytics, a public JavaScript CDN, and the Stripe payment script can all run while anything else gets blocked. The header doubles as documentation for which third parties you've consciously approved.

Report-only mode

Input

Test CSP without breaking, send violations to logging endpoint

Output

Content-Security-Policy-Report-Only: default-src 'self'; report-uri /csp-report

Report-only mode is invaluable for rolling out a CSP without taking down a feature. The browser logs every violation to the URL you specify but lets the page keep working, so you can audit real traffic for surprise inline scripts or third-party dependencies before flipping over to the enforcing Content-Security-Policy header.

Tips & Best Practices for CSP Header Generator

1.Start strict and loosen only when you have to. Beginning with a permissive policy and trying to tighten later almost never catches the real issues, because nothing will be visibly broken to push you toward a fix. A strict baseline with named exceptions for the few things that genuinely need them is far more defensible.
2.Avoid 'unsafe-inline' for scripts wherever you can. It effectively undoes most of what CSP is buying you, since any injected script tag will then execute. Move inline event handlers and inline blocks into external files, and you'll get a meaningful security upgrade with one refactor.
3.If you genuinely cannot eliminate inline JavaScript, fall back to nonces or SHA-256 hashes rather than 'unsafe-inline'. Generate a fresh nonce per request, embed it in script-src as nonce-abc123, and add the matching nonce attribute to each script tag — that way only your inline blocks run.
4.Roll new policies out in report-only mode first. Almost every site has at least one inline handler or third-party iframe nobody remembers adding, and discovering that with a logging endpoint is much better than discovering it from a Sev-1 ticket five minutes after deployment.
5.Wire up violation reporting from day one. The legacy report-uri directive and the newer report-to mechanism both push CSP violations to an endpoint you control, and the resulting feed is genuinely useful for spotting attempted attacks, finding code that needs fixing, and noticing when a third party silently moves to a new domain.
6.Treat your CSP like a dependency manifest. Anytime you add a new analytics provider, swap CDNs, or pull in a payment SDK, the policy needs an update too. An out-of-date CSP is a guaranteed source of broken features in production once the third-party request gets blocked.

Frequently Asked Questions

It's an HTTP response header (occasionally a meta tag) that tells the browser which sources are allowed to provide scripts, styles, images, fonts, and other resources for a page. Its main purpose is XSS defense in depth — even when an attacker manages to inject a script tag, the browser refuses to execute it unless the source matches the policy. That makes CSP one of the strongest layers of defense in any modern web app.

CSP Header Generator

About CSP Header Generator

How to Use CSP Header Generator

Choose policy strictness

Add allowed sources per directive

Configure inline handling

Test in report-only mode

When to Use CSP Header Generator

XSS defense in depth

Mixed content prevention

Compliance requirements

Third-party content control

CSP Header Generator Examples

Strict baseline

Common third-party allow

Report-only mode

Tips & Best Practices for CSP Header Generator

Frequently Asked Questions

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