The keymapping is fairly natural (with some additional shortcuts). The following are some of the features.

• অ is represented by a, not o. Therefore, আ is represented by aa or A, and ও is represented by o.
• For the longer sounds, type twice or use capital letters, i.e., aa or A for আ, ii or I for ঈ, uu or U for ঊ, and so on.
• ঋ is represented by wri.
• For অ্যা and এ্যা type aaY and eeY.
• For the aspirated sounds, use h, eg. kh for খ, gh for ঘ, etc.
• For the harder/longer sounds, type in capitals, e.g. T for ট, Th for ঠ, D for ড, N for ণ, R for ড়, J for য.
• ঙ is Ng, ঞ is Nj.
• ng is encoded as ং if followed by a consonant, otherwise as ঙ্গ.
• শ, স and ষ are sh, s and S (or Sh), respectively.
• For ্ use `.
• ব is encoded both as b and as w; y encodes য়, except when it follows a consonant, when it (as well as Y) encodes য-ফলা. The only difference between them is the behavior when following গ: gy is জ্ঞ and gY is গ্য.
• For juktakkhors, type the consecutive consonants. For example, ndr for ন্দ্র, kt for ক্ত, shr for শ্র. Therefore, ব-ফলা is w, র-ফলা is r, য-ফলা is y.
• Some juktakkhors have shortcuts (like gy for জ্ঞ and গ্য use gY). Some extra ones are nj for ঞ্জ, x for ক্ষ (the usual method to enter ক্ষ would have kS). I will leave the rest to you to discover for yourself.
• ঃ is represented by H; for ঁ, use ~ or ^.
• It is often useful to disrupt the phonetic transliteration; use # or $. For example, to type করতে, type kar#te; if you type karte, you get কর্তে; you may also type karate to get করতে, although that is a bit unnatural. This is also needed to write certain combinations. For instance, to write ওই, type o#i, since oi converts to ঐ.
• To type some strange juktakkhors, you need to type the hasanta explicitly. For example, for ক্হ, type k`#h, since kh is খ.

Some examples.

• বাংলা bAnglA or baanglaa
• রবীন্দ্র rabIndra
• তৎক্ষণাৎ tat`xaNAt`
• নমোঽস্তুতে namoostute
• হ্যাঁ hyA^
• তত্ত্বালোচনা tattwAlochanA
• জিজ্ঞাসা jigyAsA
• ভাগ্য bhAgYa
• পরেদ্যবি paredyabi
• সন্ধ্যার্ঘ্য sandhyArghya
• কলকাতা kal#kAtA

Copyright (C) 2021 Sucharit Sarkar. This code is covered under the GNU GPLv3. In summary, you may inspect, modify, and redistribute the code at your free will, as long as you include your source files and preserve the original copyright notices.