SQLite vs Firebase vs Web(HTTP GET POST) vs Tiny Web DB

i want to make 2 app , the first app is a login and register app and the other one is a chat app , and i created a MySQL Database and i know how to use HTTP GET and POST on Xcode , but i want to ask that how can i do it on Makeroid , And i only know how to use Tiny Web DB , so i want to ask that which database components is better to use if i have already created a MySQL Database and i want to know that the Pros and Cons of SQLite , Firebase , Web and Tiny Web DB , and please also talk about how to use for each of these Database Components