If you are in Singapore and looking at applying for a Thai visa at the Thai Embassy in Singapore then you can look on this website for the contact details of the Embassy and also look at the fees for each visa available. Note that there have been visa changes over the last few years for Singaporeans. These have been added below as a Singaporean does not need a tourist visa for Thailand however there are now limitations on how many times a land border can be used.
Thai Embassy Singapore – Thai Visa
As a Singaporean you can enter Thailand without a visa for 30 days with the visa waiver program. Since 2016 however you can only enter Thailand without visa through land border checkpoints only twice a calendar year. This is important if you are going to go through the Hat Yai immigration point by land through Malaysia or are going to backpack through Thailand. Note also that for on-arrival-visa tourists, they must be able to prove that they have adequate finances equivalent to at least 10,000 Baht per person or 20,000 Baht per family. This is very rarely asked for proof.
Note that certain rules have been changed over the years and that the Thai Embassy in Singapore for a Marriage Visa application will want you to complete all the forms as well as show 400,000 THB as proof of your ability to support yourself in Thailand. They will require a bank statement for this as proof of funds. They now also require a letter from your Thai spouse in support of this visa. Visa Application fee: S$100 for Single Entry (Cash only in Singapore Dollars)
For theApplication you will need to provide proof of 800,000 THB in your bank account as proof of funds so you will need a bank statement and a letter from your bank. You will also require a doctors certificate to show that you do not have a prohibited diseases such as (leprosy, Tuberculosis, Elephantiasis, drug addiction, third phase of Syphilis). This cannot be older than 3 months. You will also require a criminal record check which also cannot be older than 3 months. Permanent residents from Singapore will also be required to provide their Singapore Blue IC and Re-Entry Permit Form 7. Note also that you will need to be over the age of 50 for this visa. Visa Application fee: S$250 for Multiple Entries valid for One Year.