Resources

Links I use and recommend.

Free software

darktabledarktable.orgWhat I use to turn my scans into positives (negadoctor module) and edit RAW files, instead of Lightroom.
RawTherapeerawtherapee.comAnother free RAW developer, an alternative to darktable with a different approach to colour and detail.
GIMPgimp.orgThe free image editor, like Photoshop: layers, retouching, dust and scratch removal on scans.
PIXLS.USpixls.usCommunity for photography with free and open-source tools (darktable, RawTherapee, Siril…), with tutorials and a very helpful forum.

Community & learning

Developing & scanning

Labs

Carmencita is the one I use; the rest are on my list to try.

And for the maths and the scans, see my tools.