Generally, visa requirements depend on your nationality and the purpose and duration of your visit. Find below the details for the requirements of different nationalities.
For EU/EEA/Swiss citizens: Citizens of the European Union (EU), European Economic Area (EEA), and Swiss do not need a visa to travel to Portugal for less than 90 days. Still, If you plan to settle down permanently in Portugal, you must obtain the NIF Portugal and Registration Certificate (CERTIFICADO DE REGISTO DE CIDADÃODA UNIÃO EUROPEIA). Citizens of many other countries, including the United States, Canada, Australia, New Zealand, Japan, South Korea, Brazil, and others, can enter Portugal for short stays (usually up to 90 days within 180 days) for tourism or business purposes without a visa. Citizens of countries such as India, China, Nigeria, South Africa, Pakistan, and others typically require a visa to enter Portugal for short-term stays. The specific visa requirements depend on the traveller's nationality and the purpose of the visit. Moreover, If you plan to visit Portugal from one of these countries, it is important to check the latest visa requirements and regulations. You can contact the nearest Portuguese consulate or embassy or visit the official website of the Portuguese government for up-to-date and accurate information on visa application procedures, required documents, and any changes in visa policies.