Vyapar, myBillBook and Book Keeper each write a Tally-format XML export as well as their own Excel reports. The Tally-format export is the faster path — it is read directly, the same way a Tally Day Book is, and carries masters and vouchers in one file.
Vyapar
Reports → Party Report → Excel; Reports → Item Report → Excel for the two masters. Or Menu → Utilities → Export to Tally for an XML of your masters and vouchers together — drop it on the same Pick screen and it is read like Tally's own Day Book export.
myBillBook
Reports → Party Statement and Item Report → Download Excel for the masters. In myBillBook, Settings → Export to Tally writes an XML of parties, items, sales and purchases — but payments and expenses are NOT in that export; bring those across from the report Excel instead, as a second file.
Book Keeper
Reports → each report → Export to Excel, one report at a time. Or Export → Tally XML for masters and vouchers together — drop it on the same screen; it is read like Tally's own export.
What comes across today
Parties, items, your chart of accounts with opening balances, invoices, bills, payments and journals — whichever file you bring, Excel or the Tally-format export.
What is deliberately not copied
Filed GST returns, IRNs and e-way bills stay with the portal that issued them. Bank-statement matches and attached files are not copied either. Vyapar's own bill layouts and loyalty points stay in Vyapar; myBillBook's reminder history and its own bill formats stay in myBillBook.
After you drop the file
Same five screens as every other source — matching columns, a dry run with a verdict on every record, then Import and Reconcile. The mechanics (and how undo and re-imports work) are in Import your data from Zoho, Odoo, Vyapar or a spreadsheet. Back to the full list of sources.