This is the list of countries that can enter Brazil without visa but this information is for reference only, you should always confirm it with your nearest consulate
Andorra- Argentina – Austria – Bahamas – Barbados – Belgium – Bermuda -Bolivia – Bulgaria – Chile- Colombia – Costa Rica – Czech Republic – Denmark – Ecuador- Finland – France -Germany – Great Britain – Greece – HKBNO – HKSAR – Hungary – Iceland -Ireland – Italy – Israel – Liechtenstein – Luxembourg – Macau SAR – Malaysia – Malta – Monaco – Morocco – Namibia – Netherlands – New Zealand – Norway – Paraguay – Peru -Philippines – Poland – Portugal – San Marino – Slovenia – South Africa – South Korea – Spain – Surinam – Sweden – Switzerland – Thailand – Trinidad & Tobago – Tunis – Turkey – Uruguay – Vatican.
Other countries need a visa and they have to contact the nearest Brazilian consulate to obtain it. In some cases the visa can be somewhat expensive or lengthy. Brazil basically applies the principle of reciprocity, so if a country asks for a tourist visa to Brazilians they will ask tourist visa to that country, they will charge the same fee and demand the same requirements that the other country asks from Brazilians. Americans need a Tourist Visa before arrival to Brazil, the process for Americans to obtain such visa is very similar than the process for any other country to obtain a Tourist visa to USA: it is long, expensive and you need several documents.
Visa requirements for Transiting in Brazil
The rules are clear and widespread in many of the Brazilian consulate webpage. If one will transfer in an international flight in a Brazilian airport, without abandoning the international transit area and for a time no longer than seven hours, one can do so without a transit visa. You always have to confirm this requirement with the airline and with your closest Brazilian consulate before buying the airplane ticket. Several of the consulates even advises to send them an e-mail with the complete flight information and in this way they will confirm that the passenger does not need a visa to transit in the specific airport. Remember it is the passenger responsibility to be in possession of the required immigration documents before flying. The best way to do this is a phone call to the consulate.