No visa is required for passport holders from European Union, Albania, Andorra, Antigua and Barbuda, Argentina, Australia, Bahamas, Bahrain, Barbados, Belize, Brazil, Brunei, Canada, Chile, Colombia, Costa Rica, Dominican Republic, Ecuador, Fiji, Guatemala, Honduras, Iceland, India, Israel, Japan, Kuwait, Liechtenstein, Madagascar, Malaysia, Marshall Islands, Mexico, Monaco, New Zealand, Nicaragua, North Macedonia, Norway, Panama, Paraguay, Qatar, Russia, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, San Marino, Sao Tome and Principe, Saudi Arabia, Singapore, Solomon Islands, South Africa, South Korea, Switzerland, Turkey, Trinidad and Tobago, Tuvalu, Ukraine, United Arab Emirates, United Kingdom, United States, Uruguay, Vanuatu and Vatican.
You may be able to enter without a visa if you hold a valid Canadian, Schengen or US visa. This is not true for all nationalities, you will have to check with a consulate.
You may need to pay US$12 on arrival for a tourist card.
Visa requirements for El Salvador
El Salvador embassies