PuTTY CAC for Windows

Overview: Smart-card enabled SSH client for Windows

PuTTY-CAC is a Windows SSH client that extends the classic PuTTY by adding native support for smart cards and certificate-based logins. This free program enables secure remote shell sessions while leveraging multi-factor authentication, including hardware tokens and digital certificates (RSA, ECDSA), to strengthen access controls.

Supported authentication methods

• PKCS#11 support for interoperability with many smart card middleware solutions
• CAPI integration to use Windows certificate stores and compatible card readers
• Direct smart-card authentication combined with certificate-based keys
• RSA and ECDSA certificate workflows to enable cryptographic identity verification

Who benefits and compliance considerations

PuTTY-CAC is particularly useful for administrators and professionals who must meet strict security policies, such as those required by Department of Defense environments. It’s a practical choice when organizations require MFA and hardware-backed credentials for remote access.

Interface and usability

The client retains the familiar layout and configuration options PuTTY users expect, while adding menus and fields to manage smart-card and certificate settings. This keeps the learning curve low for existing PuTTY users but raises the security posture of SSH connections.

Alternative clients to consider

• MobaXterm — an all-in-one toolbox that bundles X server, SSH, and many network utilities with a polished GUI
• OpenSSH for Windows — a lightweight, native implementation suitable for scripting and dedicated server setups
• WinSCP — focused on secure file transfer with an integrated session manager and GUI for SCP/SFTP
• SHAREit Free — a simple, free option sometimes recommended for quick file-sharing and lightweight remote tasks

Summary

For Windows users who need hardware-backed authentication and certificate integration in their SSH workflows, PuTTY-CAC offers a secure, free solution that blends familiar PuTTY functionality with enhanced authentication features.