Apps similar to TexconvGUI include Compressonator, which is free and open source. Other options are NVIDIA Texture Tools Exporter and todds. In total there are three File Compressors like TexconvGUI for Windows, Linux and Mac.
Compressonator is a set of tools to allow artists and developers to more easily work with compressed assets and easily visualize the quality impact of various compression technologies.
Allows users compress texture files, smaller in memory mostly in DXT1-BC1 to BC7 in *.dds format.
Support: preview, cube & normal maps, mipmaps, transparency Over 130 import formats.
The standard in free GUI DXT dds compression tools for free.
todds is a CPU-based DDS encoder optimized for fast batch conversions with high encoding quality. It currently supports PNG as the input format, and BC1, BC3 and BC7 DDS files as output format.
