GST Billing & Inventory Software – PHP MySQL Source Code

A complete GST billing and inventory system in PHP and MySQL. It handles the part most billing scripts get wrong: the tax itself. Intra-state sales split automatically into SGST and CGST, inter-state sales switch to IGST, HSN codes sit on the line items, and the invoice total prints in words the way a tax invoice is expected to.

What it does

Sales run from quotation to proforma to GST tax invoice, with barcode scanning at entry and barcode label printing for stock. Purchases run through supplier purchase orders that feed live stock, with reorder levels and low-stock alerts so you find out before an item runs out. Customers carry an outstanding balance and a printable statement, payments in and out post against the ledger, and sales returns calculate their own credit.

Highlights

• Automatic SGST and CGST versus IGST split, with HSN code support
• Quotation, proforma and GST tax invoice, all printable
• Purchase orders, stock adjustments, reorder levels and low-stock alerts
• Customer statements, outstanding due tracking, payments in and out
• Sales returns with credit calculation, plus expense management and ledger
• Sales, purchase, product, customer and profit and loss reports
• Roles and permissions matrix, user impersonation, activity logs and sessions
• Database backup, Google Drive backup, SMTP email, Google OAuth and OTP login

Who it is for

Distributors, traders, retailers and wholesalers who need GST-compliant invoicing with stock and receivables in the same system — and PHP developers who want a large, finished MySQL codebase to learn from or adapt for a client.