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CSR Generator & Self-Signed Certificate Generator

Fill in the details and press Generate to get a private key, a CSR and a self-signed certificate in one go.

Your text and files never leave your browser — nothing is sent to a server.

More subject fields (organization, location, email)

Self-signed certificates are for development and testing. Browsers do not trust them, so visitors to a public site would see a warning.

Fill in the form and press Generate.

How to use

  1. Choose a key type and enter your domain as the common name (CN). For several domains or IP addresses, put one per line in the SAN box. Wildcards such as *.example.com work too.
  2. Open “More subject fields” if you need the organization, location or email. The country is a two-letter code like US.
  3. Press Generate to get the private key (PKCS#8), the CSR and the certificate in PEM format. Submit the CSR to your certificate authority and use the certificate for development or internal tests.
  4. Download the private key right away, because it cannot be recovered. For Windows or IIS, set a password and download a PFX file.

FAQ

Can I use a self-signed certificate on a live website?

No public certificate authority vouches for it, so browsers show a “Not secure” warning. Use it only for development and internal testing. For a public site, submit the CSR to a CA or use a free certificate such as Let’s Encrypt.

Is the private key sent to your server?

No. The key is created on your device with the browser’s Web Crypto API and is never uploaded or stored. It disappears when you close the page, so download it straight away.

Should I choose RSA or ECDSA?

RSA 2048-bit has the widest compatibility. ECDSA P-256 gives shorter keys and faster handshakes and is supported by all modern browsers and servers, but some very old devices and appliances may not accept it.

What validity period should I use?

One year (365 days) is a good choice for testing. macOS and iOS do not trust server certificates valid for more than 825 days, so stay below that.

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