Security Self-Audit
Some of the most well known tools to run security checks on your websites are:
- Mozilla Observatory https://observatory.mozilla.org/
- Snyk Website Vulnerability Scanner https://snyk.io/website-scanner/
- Sucuri SiteCheck https://sitecheck.sucuri.net/
Each of these tools return their assessment of the website based on various parameters (and often return scores/grades). Most importantly, they also provide remidial measures and suggestions for you to act on.
It is advised, and required, to run these as part of Maintenance Activities as well as during the Go-live process.