I would imagine most of the money goes towards:<p>- Development of the official client[1] and boulder[2], the CA server software behind Let&#x27;s Encrypt. Both are relatively big projects with lots of things to add&#x2F;improve on.<p>- Hosting CA servers in two separate data centers. HSMs for key storage are usually rather expensive as well. CRLs and OCSP are quite bandwidth-intensive[3], that&#x27;s probably where Akamai&#x27;s sponsorship comes in. Ops teams have to be available 24&#x2F;7 in case of outages.<p>- I&#x27;d guess the auditing costs are quite substantial as well. I&#x27;m not sure what&#x27;s necessary to get added to the various root programs out there (Microsoft, Mozilla etc.), but I doubt it&#x27;s free (unless that&#x27;s part of some sponsorship).<p>(I&#x27;m not affiliated with Let&#x27;s Encrypt, just my perspective)<p>[1]: <a href="https:&#x2F;&#x2F;github.com&#x2F;letsencrypt&#x2F;letsencrypt" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;letsencrypt&#x2F;letsencrypt</a>
[2]: <a href="https:&#x2F;&#x2F;github.com&#x2F;letsencrypt&#x2F;boulder" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;letsencrypt&#x2F;boulder</a>
[3]: <a href="https:&#x2F;&#x2F;blog.cloudflare.com&#x2F;the-hard-costs-of-heartbleed&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blog.cloudflare.com&#x2F;the-hard-costs-of-heartbleed&#x2F;</a>