How to Build a GST-Integrated Website for Your Indian Business

What "GST Integration" Actually Means for a Website

Many web developers claim their websites are "GST compliant" when all they have done is add a GST number to an invoice template. True GST integration for an Indian business website means something much more specific:

• Correct tax calculation: The website calculates CGST+SGST for intra-state transactions and IGST for inter-state, based on the seller's and buyer's states
• HSN/SAC code assignment: Every product or service on the website has a correct HSN or SAC code that determines the applicable GST rate
• GSTIN validation on B2B checkout: When a business customer enters their GSTIN, the website validates it against the GST portal API and auto-fills their registered business name and address
• e-Invoice generation: For eligible businesses, every B2B invoice generates an IRN from the IRP portal before the invoice is finalised
• Invoice numbering: Sequential invoice numbering per financial year as required under GST law
• GSTR-1 exportable data: All sales data stored in a structure that can be exported for GSTR-1 filing without manual reformatting

GSTIN Validation on Checkout

For B2B e-commerce or service portals, allowing business customers to enter their GSTIN at checkout — and validating it against the GST portal — is essential for both your compliance and theirs. When a valid GSTIN is entered, the system should:

1. Call the GST public API to verify the GSTIN is valid and active
2. Auto-fill the registered business name and address from the GST database
3. Determine whether to apply CGST+SGST or IGST based on the customer's registered state vs seller's state
4. Mark the transaction as B2B for GSTR-1 reporting

Without this validation, B2B invoices may contain incorrect GSTINs, which means the recipient cannot claim ITC on their purchase — a significant issue that can cost your customers lakh of rupees in denied ITC claims.

Razorpay GST Split Payments

Razorpay — India's leading payment gateway — supports routing split payments, which is critical for marketplace websites or service platforms that collect payment on behalf of service providers. Razorpay's Route feature allows the base amount and GST component to be separately routed to different accounts if needed.

For standard B2C websites, the primary Razorpay requirement is that the payment amount must exactly match the invoice total including GST — and the payment confirmation must trigger automatic invoice generation with correct GST breakup. Digitruinx integrates Razorpay payment confirmation webhooks with automatic GST invoice generation and WhatsApp delivery — the complete post-payment flow handled automatically.

e-Invoice Eligibility and Website Integration

If your business has aggregate annual turnover above ₹5 crore, you are required to generate IRN (Invoice Reference Number) for all B2B invoices. This applies to invoices generated through your website as well. A correctly built GST-integrated website checks e-Invoice eligibility for each transaction and calls the NIC IRP API to generate IRN before finalising the invoice.

The technical implementation involves: authenticating with the GST e-Invoice API using your GST credentials, formatting the invoice payload in the required JSON schema, submitting to the IRP portal, receiving the digitally signed IRN and QR code, and embedding the QR code in the final invoice PDF sent to the customer.

Digitruinx builds e-Invoice generation directly into web portals for eligible businesses — this is a standard feature of the IT Portal for any business above the threshold.

GSTR Data Export from Website

Every order on your website generates a GST transaction that must be reported in GSTR-1. A properly built website stores all GST-relevant data in a structured database and provides a monthly export in the format required for GSTR-1 filing: B2B transactions (with customer GSTIN, invoice number, taxable value, tax rates), B2C large transactions, B2C small transactions summary, and credit notes.

The monthly data export should be available with one click — ideally in the JSON format accepted by the GST portal or the Excel format accepted by most filing tools. This is the feature most cheaply-built Indian websites miss, requiring manual data entry into the GST portal at month end.

How Digitruinx Builds GST-Aware Web Portals

Digitruinx's approach to GST integration in web development is systematic and built on years of Indian compliance experience. Every Digitruinx web portal includes:

• HSN/SAC master database seeded for the client's product/service categories
• State-wise GST rate calculation with automatic CGST/SGST vs IGST determination
• GSTIN validation API integration for B2B checkout
• e-Invoice API integration for eligible businesses
• Sequential invoice numbering with financial year reset
• Monthly GSTR-1 export in JSON and Excel formats
• Razorpay integration with automatic invoice generation on payment confirmation
• WhatsApp invoice delivery with PDF attachment