Client SSL certificate setup Setup server SSL certificate. Certbot can help you with that; Create client self-signed certificate (will work 365 days): openssl req -newkey rsa:2048 -sha256 -nodes -keyout vkapi.key -x509 -days 365 -out vkapi.crt -subj "/C=RU/ST=Saint Petersburg/L=Saint Petersburg/O=VK API Club/CN=vkapi" openssl pkcs12 -export -in vkapi.crt -name "Test" -descert -inkey vkapi.key -out vkapi.p12 -passout pass: Go to your VK community page, "Manage" > "Settings" > "API usage" > "Callback API" > "Server settings" and upload vkapi.p12 file; Add following lines to the nginx config: ssl_client_certificate </path/to/vkapi.crt>; ssl_verify_client on; ssl_verify_depth 0; Restart nginx: sudo service nginx restart