How to Add Security Headers to Caddy
Add CSP, HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy to Caddy. Copy-paste configuration included.
The 6 Essential Security Headers
Content-Security-Policy (CSP)
Controls which sources of scripts, styles, and resources are allowed. Prevents XSS by blocking inline scripts and unauthorized external scripts.
Strict-Transport-Security (HSTS)
Forces browsers to always use HTTPS, preventing protocol downgrade attacks and cookie hijacking over HTTP.
X-Frame-Options
Prevents your page from being loaded in an iframe, blocking clickjacking attacks.
X-Content-Type-Options
Prevents browsers from MIME-sniffing the content type, stopping attacks that rely on content type confusion.
Referrer-Policy
Controls how much referrer information is sent with requests, protecting user privacy and preventing information leakage.
Permissions-Policy
Controls which browser features (camera, microphone, geolocation) your page can use, reducing attack surface.
Caddy Configuration
Add this to Caddyfile in your Caddy configuration directory (typically /etc/caddy/Caddyfile):
# Caddyfile
yourdomain.com {
# Security headers
header {
X-Frame-Options "DENY"
X-Content-Type-Options "nosniff"
Strict-Transport-Security "max-age=63072000; includeSubDomains; preload"
Referrer-Policy "strict-origin-when-cross-origin"
Permissions-Policy "camera=(), microphone=(), geolocation=()"
Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"
X-XSS-Protection "1; mode=block"
-Server # Remove Server header
}
reverse_proxy localhost:3000
}Caddy automatically provides HTTPS via Let's Encrypt — no certificate management needed. Use -Server to remove the Server header. The header directive applies to all responses. Reload after changes: sudo systemctl reload caddy
How to Test Your Headers
curl -I https://yourdomain.comOr use Cybrove's free security check to automatically validate all security headers and get specific fix recommendations.
Frequently Asked Questions
How do I add security headers to Caddy?
Add security headers to Caddy by modifying Caddyfile in your Caddy configuration directory (typically /etc/caddy/Caddyfile). The essential headers are CSP, HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy. See the configuration example above.
How do I test if my Caddy security headers are working?
Run: curl -I https://yourdomain.com and check the response headers. Or use Cybrove's free security check at cybrove.com/scan which automatically validates all security headers and reports which are missing.
Which security headers are most important for Caddy?
CSP (prevents XSS), HSTS (forces HTTPS), and X-Frame-Options (prevents clickjacking) are the most critical. X-Content-Type-Options and Referrer-Policy provide additional protection with minimal configuration effort.
Check if your Caddy headers are configured correctly
Free security check validates all 6 headers plus SSL, DNS, and email authentication.
Free Security Check