In Hungary, the official local currency is FORINT (HUF) since 1946. The name comes from the name of the city Florence, where golden coins had been minted.
You have a lot of options for changing currencies in Hungary. One of them is changing at banks and ATMs. There are a lot of exchange shops around Budapest and many of them are not charging any commission.
Credit cards are accepted at most places in Budapest, but in some smaller shops you can only pay by cash. If you have doubts, look for symbols and tags of the accepted cards on the window of the shop. The most popular credit cards are VISA, MasterCard and American Express.
Please note, that some shops accepts Euro but the exchange rate can be worse than the official.
You can find the official daily exchange rate at: https://www.mnb.hu/en/arfolyamok