The local currency is Tanzanian Shilling (Tzs). Many hotels require payment in US$, in particular for accommodation, but also for food and drink and for tours. Taxis and car rentals are also paid in US$. You do need Tzs if you go shopping in the villages or eat at local restaurants (recommended!) and for petrol if you rent a car. Tzs come in notes of 10,000, 5,000, 2,000 and 1,000 shillings. Coins used here are 500, 200, 100 and 50 Shilling.
The Government recently closed all exchange bureaus in Stone Town. At present, one can only exchange money at the local banks, their new exchange bureau outlets and at the Post Office in Shangani. Apparently new regulations for exchange bureaus are being formulated as well as a proper registration process.
The exchange bureaus inside the airport arrivals and departures halls are still open 24/7. You get better rates for $100 and $50 notes. NB: latest news is that only US$ notes printed after 2013 will be exchanged!
For an indication on current exchange rates check https://crdbbank.co.tz/exchange-rates/
The bigger hotels, restaurants and car rentals have credit card facilities. A surcharge of 5% is applicable. Be aware that at many places credit cards are not accepted.
ATMs: You can only draw Tzs against your credit card or a card with a Visa or Mastercard logo. An ATM is at the airport parking lot, there are a few other ATMs in Stone Town. Most ATMs have a maximum payout of Tzs 400,000 per withdrawal. You can use your credit card multiple times until your daily withdrawal limit on your credit card is reached. You might have to visit different ATMs though.
There are NO ATMs outside of Stone Town, with these 2 exceptions:
Paje: The Barclays ATM is at the UP petrol station close to the police checkpoint
Dunga: The NMB ATM is between Dunga and Koani (central Zanzibar)
Petrol costs Tzs 2376 per liter for Super (mid June 2019) and is paid in Tzs. You can also pay in US$ but you’ll get a really bad exchange rate.
Simcard/internet: You can buy a simcard at the airport. A Zantel simcard loaded with 3GB costs US$ 20 (Zantel is the service provider with the most coverage on Zanzibar).
Wi-Fi hotspots in Stone Town are at the airport, ferry port, at Forodhani Gardens, Mercury’s Restaurant and La Taverna restaurant. Most hotels and restaurants offer free Wi-Fi for their guests.