There was a download of Luminance HDR 2.6 on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The program is included in Photo & Graphics Tools.
The Luminance HDR installer is commonly called luminance-hdr.exe or luminance.exe etc. The latest version of the software can be downloaded for PCs running Windows XP/Vista/7/8/10/11, both 32 and 64-bit. This free program is an intellectual property of Davide Anastasia, Franco Comida.
The most popular versions among Luminance HDR users are 2.4, 2.3 and 2.2. We cannot guarantee that the program is safe to download as it will be downloaded from the developer's website. Before launching the program, check it with any free antivirus software.
From the developer:
Luminance HDR is an open source graphical user interface application that aims to provide a workflow for HDR imaging. You can create an HDR file from a set of images (formats: JPEG, TIFF 8-bit and 16-bit, RAW) of the same scene taken at different exposure setting.
You may want to check out more software, such as Luminar 3, HDR Projects platin or HDR Efex Pro, which might be related to Luminance HDR.