I need a production-ready solution that plugs into Tally, reads and writes data seamlessly, and removes as much manual bookkeeping effort as possible for a handful of our chartered-accounting clients. The platform must cover three flows: Expense Invoices • Capture PDFs or scanned bills with OCR, push the key fields into structured tables, let a reviewer tweak anything the model is unsure about, then post the clean voucher straight to Tally. The workflow should also fetch existing ledgers from Tally so duplicate supplier names or GSTINs are never created. Sales Invoices • Our clients already raise invoices in their own software; I want those documents pushed into Tally through an API route, not by file upload. A lightweight mapping screen is fine, but the transfer itself must be fully automated and two-way (status updates back to the source app). GST Compliance • For every purchase entry the system should ping the GST portal (or consume the downloaded JSON) and confirm that the vendor bill appears in GSTR-2B. Any mismatch, rate error, or duplicate credit must be flagged on a dashboard and exported for follow-up. Core expectations – End-to-end Read/Write integration with Tally via XML, ODBC, or TDL gateway—whichever delivers the most stable throughput – Robust OCR layer (Tesseract, Google Vision, or similar) blended with a quick manual-edit screen so tricky images never break the process – Clean, searchable database and audit logs for every sync event – Role-based access and client segregation; each firm’s data must stay ring-fenced – Clear deployment guide so my in-house team can host it on our own server I’m comfortable with Python, Flask/FastAPI, and Postgres if that helps you frame the stack, but I’m open to other proven approaches provided the end result meets the three functional pillars above and can scale to roughly 20,000 vouchers a month without a rewrite. When you respond, please outline: 1. The libraries or SDKs you’d use for Tally connectivity 2. Your preferred OCR and GST API strategy 3. A timeline with key milestones from prototype to final roll-out A concise demo or screen capture of a similar integration you’ve completed will move your bid to the top. Would prefer developers who are based in Mumbai, and should have experience working with Tally XML import/export.