OpenSSL 3 · Certificates
Create a self-signed certificate
Create a key and certificate valid for a year, for testing only.
openssl req -x509 -newkey rsa:2048 -nodes -keyout key.pem -out cert.pem -days 365 -subj "/CN=localhost" -addext "subjectAltName=DNS:localhost,IP:127.0.0.1"
Caution: Browsers don't trust self-signed certificates. Use them only for local development.
Official OpenSSL 3 documentation