Connect the books to the tools already in use.
Seven triggers (new invoice, invoice paid, new bill, new payment, new customer, new supplier, new promise), two actions (create customer, create invoice with GST computed), three searches — with ready-made setups for Google Sheets, Slack, Gmail, Google Calendar, Google Forms and Shopify.
The same per-business key works from anything that speaks HTTP; amounts in rupees, rates in percent.
Each person connects their own Gmail or Google Workspace mailbox with a single permission — send email — so invoices leave from their address; nothing here can read their mail.