BASIC and ATR file hacking around - good ATR writer?

[Biggles]

So - I used to do lots of BASIC coding, and the BASIC support is a key feature for me. A big question to answer is how to get BASIC code in/out of the 400 mini, aside from typing it in like I used to from magazines.

 

For *export* - I found this works fantastically: https://pvbestinfoo.github.io/atari8-bit_rom_image_file_explorer.html

 

The above lets me save files to the ATR on the 400 mini and export them to regular text files in the "real world". What I can't find is an ATR *writer* that works reliably outside of windows - every one I try runs into errors I suspect are library-related but haven't troubleshot yet. Suggestions for ATR-processing utilities you've used successfully are welcome.