You want a multi-step form in n8n. Each step's dropdown depends on what the user picked or uploaded in the previous step. You search for "n8n dynamic dropdown" and find static fieldOptions examples and the occasional "use a Code node and hope."
I had the same problem building the distribution workflow for LDX hub, an AI document processing API. I wanted one workflow where a user picks one of five services, then walks through engine selection, file upload, and output format — with every dropdown computed from the previous step.
It turns out n8n already supports this. The feature is just hidden behind one toggle on the Form node.
This post walks through the pattern, with working code, three things to watch out for, and a link to a complete reference workflow you can import.
The one toggle that changes everything
