I’d probably just start with a blank Word doc, write an introduction and mock up some diagrams using the inbuilt tools Word has. I don’t think a template is req

I’d probably just start with a blank Word doc, write an introduction and mock up some diagrams using the inbuilt tools Word has. I don’t think a template is required for a small web app. Hire someone to build it who doesn’t just blindly follow specs to the letter. You’d get a better outcome. And you can spend less time on making the spec a contract and more a simple communication tool that is the beginning of a dialogue.