The Thai alphabet can feel overwhelming due to the high number of consonants and vowels. Ive prioritized the order in which I believe you should learn the letters. I came up with this order over many years of teaching Thai to foreigners and it is what I use in my much more comprehensive online course, Read Thai in 2 Weeks. Its worth noting that I purposely leave out the least common consonants and vowels as the rarer items are just a distraction for those just starting out.
The letters of the alphabet are split up into 3 groups generally known as "consonant classes" and this app allows you to quickly look up a letter to see what class a particular letter is which is necessary in determining the tone. You will eventually need to learn what class each letter belongs to, but during those first couple of weeks when you will inevitably forget which class a consonant belongs to, this may be useful.
Note that this is not intended as an all-in-one app, but rather it is to help you quickly look up and review individual letters (and their respective sound and class) no matter what level you are. The current version does not include any explanations on how to pronounce any of the consonants or determine the tone of word. Most importantly, it does not include transliteration. Transliteration may seem helpful, but it will mess up your pronunciation and in the same amount of time you could have just learned the alphabet.