Make sure to apply for a visa before your trip to Sri Lanka. You can apply for an Electronic Travel Authorization (ETA) online, which usually takes a few minutes to process.
The official website to apply for an Electronic Travel Authorization (ETA) for Sri Lanka is https://eta.gov.lk/etaslvisa/.
Regarding visa information, you can contact the official source for visas and immigration in Sri Lanka.
Department of Immigration and Emigration
Ananda Rajakaruna Mawatha,
Maradana,
Colombo 10.
Tel:+94-11-5329000/+94-11-5329316/20/21/25
www.immigration.gov.lk