### Installing or Upgrading TQSL

The TQSL application used by LoTW is free to download and use, and is available for Microsoft Windows and Apple OS X. If you are running anti-spyware or anti-malware applications such as Bit Defender, configure these applications to allow TQSL to run.

Note : TQSL can submit digitally signed QSOs and Callsign Certificate requests to LoTW via the internet. The firewall or another anti-malware application on your computer may by default prevent TQSL: from accessing the internet. Consult the documentation for the application you're using to learn how to declare TQSL as "safe" so it can access the internet.

The current version of TQSL is 2.4.1 . If you have an older version of TQSL installed on your computer, you normally need not un-install it; installing the current version will replace the older version.

##### Installing TQSL on Microsoft Windows

TQSL will run on the following versions of Microsoft Windows:

- Windows 2000
- Windows NT
- Windows XP (32-bit and 64-bit)
- Windows Vista (32-bit and 64-bit)
- Windows 7 (32-bit and 64-bit)
- Windows 8 (32-bit and 64-bit)
- Windows 10 (32-bit and 64-bit)

Download TQSL 2.4.1 for Windows here .

Troubleshooting while upgrading from TQSL version 1.x

##### Installing TQSL on Apple OS X

TQSL will run on both PowerPC and Intel processors on OS X version 10.4 and later. Download TQSL 2.4.1 for OS X here .

##### Building TQSL for Linux

Linux users can build the software from the source code for the tqsllib library, and the TQSL 2.4.1 application, which is available here. ARRL does not maintain packages for the many Linux distributions. For assistance with obtaining a packaged version for your Linux distribution, contact your distribution's maintainer.