Site Scan from MS - https://dev.windows.com/en-us/microsoft-edge/tools/staticsca...
Subresource Integrity scanner - https://sritest.io/
These are all good but I would include the following:
Qualys SSL Server Test - The first site I use.
testssl.sh - for behind the fireware testing
https://tls.imirhil.fr/ - this one is nice because it shows the ciphers used/avail broken down by TLS version. I have not seen any other site do this.