Thailand is a party to hundreds of international treaties. There is no official Thai treaty series - nor a Thai online platform containing all treaties to which it is a party. The best way to find all bilateral and multilateral treaties to which Thailand is a party is to use the United Nations Treaty Series Online - this resource is official and up to date. Select Participant Search from the top menu, and then Thailand from the drop down list of countries. To cite treaties, use the UNTS citation provided in this database.
Wikipedia also lists many bilateral and multilateral treaties to which Thailand is a party.
In general, most treaties cannot be signed and ratified by the Executive alone - parliamentary approval or the signature of the King is required for Thailand to become a party to the treaty. Article 178 of the 2017 Constitution provides that:
Once ratified, treaties are not automatically binding in Thailand.Thailand has a dualist approach to incorporating treaties into domestic law - treaties are only binding on Thai courts if they have been transformed into a national law by, for example, an Act of Parliament. Under traditional Thai practice, if a treaty is already consistent with Thai laws, it does not need to be ratified by Parliament. However, without such ratification, it cannot be invoked directly in domestic courts as binding on those courts. With regard to human rights treaties, although the Constitution is silent on this point, there is still an international obligation not to undermine a human rights convention, with or without a national law to implement it. Some domestic courts are quite active in referring to international treaties, even if there is no domestic law that implements them directly.
Source: Vitit Muntarbhorn, The Core Human Rights Treaties and Thailand (Brill, 2016) 5-6, 9
See also the following open access articles:
The Rule of Law in Armed Conflict (RULAC) Project website includes information on the international human rights and humanitarian treaties and regional treaties to which Thailand is a party, along with relevant national legislation.
Thailand is a party to 7 out of the 9 core human rights treaties (implying full legal commitment), and has signed but not ratified the International Convention for the Protection of All Persons from Enforced Disappearances (CED), indicating a political commitment which is not yet fully binding. To date It has not signed or ratified the Convention on the Protection of the Rights of All Migrant Workers and of their Families (CMW).
Thailand has also signed but not ratified the Rome Statute on the International Criminal Court.
The RULAC international treaties page also lists all reservations, derogations and declarations made by Thailand on each human rights and humanitarian law treaty - however, although handy, this site has not been updated since 2012 and, for example, several declarations have been withdrawn since then. So always check the up to date participant information on the official United Nations Treaty Series Online database - this lists reservations, ratifications, objections etc.