Deskproto is one option but isn't free. Fusion 360 paid version does 4 axis indexed if that is good enough (that's £360/yr).

I build my 4th axis just before Fusion pulled their cunning stunt. Took me a while to cool down while my handiwork sat on the shelf but finally I swallowed my pride and coughed up.

Here's the kind of work you can do with indexed 4th axis:


For "true" 4th axis with curved surfaces etc, you'd need to pay for their damned "manufacturing extensions". These cost £1848/year, so hobby users can go whistle. Deskproto is 250 Euros to purchase. I didn't find anything else but may have missed something. Hopefully somebody will come along and fill the void.

I imagine Fusion pricing has blown a hole in the sales of PocketNC https://pocketnc.com/. They still present Fusion's 5 axis toolpaths as viable options for home use, yet £1848 on top of the base subscription seems a bit on the high side to me. https://www.autodesk.co.uk/products/...ning-extension