Before you can get an SSL certificate from a Certificate Authority, you need to generate a Certificate Signing Request (CSR). The CSR is a block of encoded text containing your domain name, organisation details and public key. You submit it to the CA, they verify your domain, and issue your certificate.
The Anonymiz CSR Generator creates a CSR and private key pair in your browser — no command line or software installation required.
What Is in a CSR?
A CSR contains the fields that appear in your SSL certificate:
- Common Name (CN) — The domain the certificate secures. Use *.example.com for a wildcard.
- Organisation (O) — Your company name. Required for OV and EV certificates.
- Country (C) — Two-letter country code (US, GB, DE etc.)
- Subject Alternative Names (SANs) — Additional domains. Modern certificates require at least one SAN.
How to Generate a CSR
Enter your domain in the Common Name field. Add any additional domains in Subject Alternative Names separated by commas. Fill in organisation details if your CA requires them. Choose 2048-bit (standard) or 4096-bit (high security) key size. Click Generate CSR and Private Key.
The tool outputs two blocks. The CSR starts with -----BEGIN CERTIFICATE REQUEST----- — submit this to your CA. The private key starts with -----BEGIN PRIVATE KEY----- — this stays on your server and is never shared.
What to Do After Generating
- Copy the CSR and paste it into your CA portal (Lets Encrypt, DigiCert, Comodo, ZeroSSL etc.)
- Save the private key securely on your server — you need it when installing the certificate
- Complete domain verification with your CA
- Download and install the issued certificate alongside the private key
- Use the Certificate Key Matcher to verify they match before restarting your server
CSR Security Tips
Never share your private key. If you suspect it was compromised, generate a new CSR immediately and request a replacement certificate. For maximum security, generate your CSR directly on the server using OpenSSL: openssl req -new -newkey rsa:2048 -nodes -keyout private.key -out request.csr
The free CSR Generator supports domains, wildcards, SANs and 2048 or 4096 bit key sizes. No signup required.
