Summary of implementations, library support, and protocol integration
Much of TLS 1.3's uptake is due to widespread support for the protocol being added to existing TLS implementations. Major TLS implementations such as NSS, BoringSSL, OpenSSL, GnuTLS, wolfSSL have all added support for TLS 1.3, in addition to TLS 1.2 and earlier versions of the protocol.
However, we have also seen stacks with only TLS 1.3 support emerge. These include production implementations such as Facebook's Fizz. Popular languages and system frameworks such as Go, Swift, Java, rustls, and Apple's Network.framework also include support for TLS 1.3 by default. And, of course, all major browsers, including Chrome, Firefox, and Safari support TLS 1.3 by default. (If you are running on a different browser, you can check out SSL-labs to test for TLS 1.3 support.)
Several experimental, i.e., not production ready, TLS 1.3 implementations used mainly for protocol interop and ease-of-use also exist. These include Tris, Mint, picotls, and rusttls. These implementations are important, especially with the ongoing development of QUIC.