Save this on your USB (Drive E:). Run it on the target computer. It installs the font for the current user only (no admin rights needed). Reboot the PC and the font is gone. This is the holy grail of portability.
This is the gold standard for Tamil typing. It has a portable version that doesn't require installation. jf banumathi font portable
This happens when the software cannot read the Unicode mapping. Ensure you are saving your original file in Unicode (UTF-8) format, not ANSI. If you type in Banumathi but save as plain text, the encoding breaks. Save this on your USB (Drive E:)
This is normal for portable workflows. Portable fonts are "volatile" by design. To fix this, keep the font file open in the background (the preview window) or use the PortableApps Font Loader plugin which creates a symlink. Reboot the PC and the font is gone
Portable tools can "load" the font temporarily while the application is running, making JF Banumathi available in Word, Photoshop, or Excel only for that session. How to Use JF Banumathi Portably