FlowSsh: SSH client library for C, C++ and .NET

The same SSH library as we use in our SSH server for Windows is available for licensing for SSH client applications.


  • Separate easy to use interfaces for C, C++, and .NET.
  • Fully documented.
  • Comes with several complete sample applications in C, C++, C#, and Visual Basic.
  • Full support for public key authentication.
  • Full support for SFTP and tunneling / port forwarding.
  • Support for general channel types, including exec requests and terminal sessions. (Terminal emulation not included.)
  • Supports ZLIB compression. (But does not use the widely used zlib library.)
  • Supports connecting through a proxy.
  • Uses a FIPS 140-2 certified cryptographic module (included).
  • Pluggable cryptographic interface allows substituting a different cryptographic module.
  • Compatible with both 32-bit and 64-bit Windows applications. (Non-Windows platforms not supported.)
  • Code base separate and independent of other SSH implementations.
  • Does not contain parts subject to GPL or similar licenses.


FlowSsh 5.34 is available for download. License terms and build instructions are included in the archive.

Use of FlowSsh for evaluation and testing is free of charge. To include FlowSsh in your production application, contact us.


Complete FlowSsh documentation can be found here.


FlowSsh is priced at USD 599.95 per developer, or USD 1,999 per application.

A per-developer license is valid for any number of programs and applications, but requires a fee for each developer involved in writing programs that use FlowSsh. You can purchase a Per-Developer License here.

A per-application license is valid for a single, specific application, but permits use by an unlimited number of developers. You can purchase a Per-Application License here.

There are no royalty fees based on use of the resulting applications. Use in commercial programs is permitted and encouraged.

A full source code license, including the source code to the FlowSsh DLL, is also available. Please contact us for more information. The cost of this license is USD 5,000.

Architectural Limitations

In our current design, FlowSsh is incompatible with applications that use .NET Application Domains. The FlowSsh implementation makes heavy use of fibers, which .NET Application Domains do not support. This means FlowSsh is currently not a suitable choice for use in ASP.NET (within an IIS process).


You may post messages in our public FlowSsh support forum free of charge. Such messages may be read and replied to by FlowSsh developers, as well as by other FlowSsh users.

Bug reports are handled free of charge. Please contact us if you would like to suggest a feature or report an issue.

Private support to help you use FlowSsh is available at a cost of USD 100 per hour.