Tamil Fonts Converter - for macOS - Convert from any Tamil font encoding to any other Tamil font encoding (SaiIndira, Unicode, Stmzh, Bamini, Shreelipi, etc.)

It is inbuilt into the latest version of 'Azhagi for Mac' app (azhagi-for-mac.php), just in the same way it is inbuilt in the Windows apps (Azhagi+, Azhagi++, AAW, etc.).
So, you may please visit the download section of Azhagi for Mac app, read the instructions therein, email me to obtain (for free) the download link for the "latest version" of 'Azhagi for Mac' and thereafter you can start using the inbuilt 'Tamil fonts converter' in it.

Note: There are actually 2 versions of 'Azhagi for Mac' (older and latest). The older version 18 can be freely downloaded by all. For the latest version, one has to email me to obtain its download link (for free).

It is, as such, self-explanatory.

You can access the converter from the 'Tools' menu and also by clicking the 'Converter' button on the starting screen of 'Azhagi for Mac'.
You can always click the 'Convert' button to effect the conversion.
If 'Auto Convert' is kept on, the conversion takes place automatically even without clicking the 'Convert' button.
The 'Font Selection Assister' buttons assist you to quickly set a font for each of the 'from' and 'to' encodings so that after after pasting the text in your 'from' box, the 'from' box shows the Tamil text in Tamil itself (as you can see in the screenshot above). Similarly, after conversion, the 'to' box also will show the Tamil text in Tamil itself.
The 'Auto Detect' option is quite a powerful one. But, please note that, more the text you paste in the 'from' box, more the accuracy. The listbox below the 'Auto Detect' option lists the fonts detected for the pasted text, ranked in the order of 'most probable' to 'least probable'.
In case the top-detected font encoding does not seem to be correct, you can always click on 'the encodings listed below the top-detected encoding', one after the other. If Auto-Convert option is ON, the conversion will take place automatically for each of the encodings and you can easily 'zero in' on which encoding is the correct one for the pasted text.
The 'Normal quotes' option is effective during Non-Unicode to Unicode conversion only.
The 'New form of ir/ri/ree' option is effective during Unicode to NonUnicode conversion only.
The 'Convert single vowel signs' option is useful when you try to convert sentences like below:
தமிழில் உள்ள உயிர்க்குறிகள்: ா ி ீ ு ூ ெ ே ை ொ ோ
For any pasted text, with 'Auto Convert' ON, you can keep selecting all the 'To' encodings one after the other (either using the mouse OR the keyboard), to see the conversion of the pasted text in each of the 'To' encodings.
Actually, you can even type straightaway in the 'From' text box in Unicode, Bamini, etc. (pressing Alt+3, Alt+B, etc.) and you can see the converted text appearing automatically in the 'To' text box.