Is the Zettelkasten an evidence-based memory method?

No — it's a knowledge-management system (associated with sociologist Niklas Luhmann), excellent for developing ideas over time, but with essentially NO controlled evidence as a memorisation technique.

A Zettelkasten ("slip-box") is a network of atomic notes — one idea per note — that you cross-link to each other, building a web of connections you can navigate and grow. It's beloved by writers and researchers for long-term thinking, and it's consistent with sound principles like elaboration and connection-making.

But be clear about the claim: as a technique for memorising material for an exam, there is essentially no controlled cognitive-psychology evidence behind it. It's a superb tool for developing and connecting ideas, especially for writing — not a shortcut for retention. Don't confuse "great for thinking" with "proven for remembering."