Link: https://www.ghidra-sre.org/
This was released a few days ago but today I was suprised to learn that it actually supports Z80 as a machine architecture. I've only been trying it for a few minutes now but it seems pretty good. This is the tool being used on Manic Miner:
It's a free and open source program, so it probably hasn't got spyware built in and it looks like it would be quite useful for making disassemblies of Spectrum games. Has anyone else tried using this?