I made a little spin-off of ASM80 IDE. You can use the compiler locally, offline, in a simple way.

Visit asm8080, asm6502, asm6809 or asmZ80. You can save these files to your PC (Ctrl S, or right click to the link and Save as…)

Usage is really simple: Just open the HTML file in your browser. Copy and paste the source code into a Source window and press Compile.

And yes, it provides all features of the “full” ASM80.