From Shabaka Soft Ltd.:
Type Bangla using this phonetic keyboard. Very easy to use. Keyboard supports most modern English to Bangla phonetic typing method. Once done click on email button to send it to anyone. You can also copy paste and save it in any other application such as Notes. No need to learn any specific keyboard. This keyboard uses english phonetic typing method. for example you will type 'Amar sonar bangla' to see it in Bengali font. To do a combination character you will join it with q character. for example t+q+t will give you bangla 'ta' conjunction.