s2n-tls

s2n-tls
Original authorColm MacCárthaigh
DeveloperAmazon Web Services
Stable release
1.6.3 / 10 December 2025 (10 December 2025)
Written inC99
Operating systemCross-platform
TypeSecurity library
LicenseApache License 2.0
Websitegithub.com/aws/s2n-tls
Repository

s2n-tls, originally named s2n, is an open-source C99 implementation of the Transport Layer Security (TLS) protocol developed by Amazon Web Services (AWS) and initially released in 2015. The goal was to make the code—about 6,000 lines long—easier to review than that of OpenSSL—with 500,000 lines, 70,000 of which are involved in processing TLS.