acme.sh supports free SSL certificates

acme.sh is an open source and free SSL certificate issuance and renewal script tool. Currently, acme.sh supports five official environment CAs, namely Let’s Encrypt, Buypass, ZeroSSL, SSL.com, and Google SSL certificates. Acme.sh uses them by default. ZeroSSL, that is, if you do not specify a CA, the SSL certificate issued by the acme.sh script comes from ZeroSSL.

The advantage of acme.sh is that it can automatically apply for and renew SSL certificates for you. Except for ZeroSSL, which renews every 180 days, Let’s Encrypt, Buypass, SSL.com, and Google SSL certificates all renew every 90 days, while acme .sh can automatically renew the SSL certificate. After installing acme.sh, you don’t need to worry about the expiration of the SSL certificate.
acme.sh installation method
website:

https://github.com/acmesh-official/acme.sh
acme.sh is a Bash script that integrates the ACME client protocol. Find a VPS host and use the following command to install it.

curl https://get.acme.sh | sh -s [email protected]
If you are using a VPS, online installation may fail, you can use the source code to install directly:

git clone https://github.com/acmesh-official/acme.sh.git
cd ./acme.sh
./acme.sh –install [email protected]
Please replace [email protected] with your own email, and reload Bash after the installation is complete:

source ~/.bashrc
You can also turn on automatic updates:

acme.sh –upgrade –auto-upgrade