Calculators that price the problem, generators that produce usable first drafts, and reference tables that settle vendor arguments. Everything runs in your browser or against a public model, and nothing asks for an address before it gives you the answer.
A calculator behind an email form is a lead magnet, not a tool, and everyone knows it. These exist because they are genuinely useful to people who will never buy anything, and because an operator who has already run their own numbers is a much better conversation than one who has not.
Start with the missed-call calculator — it takes two inputs and tells you whether the rest of this is worth your time. If the number is small, stop. If it is not, the ROI calculator turns it into a payback period you can put in front of a partner or a board.