Stunnel is a proxy designed to add TLS encryption functionality to existing clients and servers without changing their code. Its architecture is optimized for security, portability, and scalability (including load balancing), making it suitable for large deployments.
Stunnel uses the OpenSSL library for cryptography, so it supports whatever cryptographic algorithms are compiled into the library. It can benefit from the FIPS 140-2 validation of the OpenSSL FIPS Provider, provided that the build process meets the OpenSSL FIPS 140-2 Security Policy. Our latest Windows installer includes the OpenSSL FIPS Provider.
Stunnel is free software written by Michał Trojnara. Although distributed under GNU GPL version 2 or later with an OpenSSL exception, stunnel is not a community project. We retain the copyright in the source code. Please contact us for commercial support or non-GPL licenses. Free, community-based support is also available via the stunnel-users mailing list.
We offer commercial support with several response-time options, including a 24/7/365 helpline.
Download the latest version of stunnel and try it yourself.
