The Polybahn takes you from Central to ETH in two minutes, which is the entire argument. Everything else about living here is expensive, and rooms in the Altstadt go through word of mouth long before they reach a listing.
Landlords in Zürich Zentrum ask for the same file as anywhere in the canton: a debt-collection extract, proof of income, and a guarantor who lives in Switzerland. Two of those are impossible before you arrive, which is why flatshares and private landlords are the realistic route from abroad.
Your deposit is capped at three months of net rent — up to CHF 4'500 at the top of the range here — and it is blocked in your own name, not the landlord's. How the deposit works
We co-sign leases so the file gets accepted, and we search the market when our own rooms are full.