There used to be some really good web-based SPICE interpreters but I can't find them now. This was before javascript ate everything, so you would enter the netlist, click a button, and get a GIF or the current at a specified terminal or whatever

Well, SPICE is still around in its zillion forks and dialects…

AIUI the best frontend is kicad, though I never really tried that, I just wrote the text files by hand.