The Thai Visa Exemption Scheme allows tourists from 64 countries to enter Thailand without applying for a visa. Travelers can visit Thailand for up to 30 days if they are entering Thailand through an international airport or land border checkpoint from a neighboring country. Check it here for the full list of the countries that are allowed to enter Thailand under the VISA EXCEMPTION RULE:
https://www.thaiembassy.com/thailand-visa/thai-visa-exemption-and-bilateral-agreement

The Visa On Arrival scheme allows passport holders of 19* listed countries and territories to enter Thailand without needing to apply for a Tourist Visa from a Thai Embassy in their own country. Learn more about this by visiting this link: https://www.thaiembassy.com/thailand-visa/visa-on-arrival