When installing an SSL certificate on your server you should install all intermediate certificates as well. If you fail to do so, some browsers will reported "untrusted" warnings for your site like this one:

Searching and downloading those intermediate certificates can be a hassle. It thought it would be a fun project to automate that boring task. The SSL certificate chain resolver, which I put on Github today, downloads these intermediate certificates for you.

You can install the package via composer: composer global require spatie/ssl-certificate-chain-resolver

Let's assume you have an incomplete certificate called cert.crt. To generate the a file containing the certificate and the entire trust chain, you can use this command: ssl-certificate-chain-resolver resolve cert.crt

A file containing the certificate and the entire trust chain will be saved as certificate-including-trust-chain.crt

You can read some more detailed instructions and some background about the trust chain in the readme on Github.