Let's Encrypt is a certificate authority that issues TLS certificates automatically to website operators, using the open ACME protocol described in RFC 8555, so that sites can enable HTTPS without manual steps. Its certificates are publicly recorded, and the CA software that runs the service, Boulder, is published under the Mozilla Public License 2.0.
Let's Encrypt is operated by the Internet Security Research Group, which describes itself as a nonprofit and gives a legal address in San Francisco, California. It is therefore not owned by a commercial company. Its privacy statement names the United States as a place where data may be transferred and processed, and says that service providers are bound by standard contractual clauses under data processing agreements. The statement includes a section on the rights of people in the European Economic Area. European organisations should note that the public service is run by a US nonprofit, while the software can be inspected and reused under its open licence.