Mobile to Tally API intergration

I need a clean, reliable bridge between my mobile and Tally so that product, party and invoice data stay perfectly in sync. The integration has to work both ways: my app must be able to push freshly-created records into Tally, and it must be able to pull any updates or new entries back out again for real-time use.

The focus is strictly on those three datasets—products, parties and invoices—nothing else for now. I am open to whichever technical route you find most stable, whether it involves TallyPrime’s XML interface, TDL customisations, ODBC, a lightweight REST layer or a hybrid of these. What matters to me is that calls from the app return the expected JSON quickly and that writes land in Tally without manual intervention.

Acceptance criteria
• End-to-end demo showing bi-directional sync of one product, one party and one invoice.
• Clear setup notes so I can reproduce the connection on another machine.
• Source code or scripts documented well enough for my internal team to maintain.

If you have proven experience integrating Tally with mobile stacks, I’d like to see an example build or brief walkthrough of how you handled authentication and error handling.