ApplicationText-based

`application/x-x509-ca-cert`

X.509 CA Certificate

Reference for application/x-x509-ca-cert, the MIME type for X.509 certificate authority certificates used in TLS trust chains.

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Expected extensions: .crt, .cer, .der

HTTP Content-Type Header

HTTP Header

Content-Type: application/x-x509-ca-cert; charset=utf-8

Associated File Extensions

.crt.cer.der

Quick Facts

MIME Type	application/x-x509-ca-cert
Category	Application
Type	Text-based (human-readable)
Extensions	.crt, .cer, .der

Common Usage

X.509 certificates form the backbone of internet security. CA certificates are used to validate TLS server certificates, establish trust chains, configure certificate pinning, and manage internal PKI infrastructure.

Every HTTPS connection relies on X.509 certificate validation.

Code Examples

HTML

<!-- Link or embed with explicit type -->
<link rel="stylesheet" href="file.crt" type="application/x-x509-ca-cert">

<!-- Or for script/media elements -->
<script type="application/x-x509-ca-cert" src="file.crt"></script>

Node.js

// Express.js
app.get('/file', (req, res) => {
  res.type('application/x-x509-ca-cert');
  res.send(data);
});

// Node.js http
res.writeHead(200, { 'Content-Type': 'application/x-x509-ca-cert' });

nginx

# nginx.conf — add to types block or use default
types {
    application/x-x509-ca-cert  crt cer der;
}

# Or set for a specific location
location /api/ {
    default_type application/x-x509-ca-cert;
}