gst_einvoice 0.1.0

Build and validate India GST e-invoice (INV-01 v1.1) JSON in pure Dart. GSTIN checks, CGST/SGST/IGST math and pre-submission validation.

example/example.dart

// ignore_for_file: avoid_print

import 'dart:convert';

import 'package:gst_einvoice/gst_einvoice.dart';

void main() {
  // 1. Check a GSTIN.
  final check = Gstin.check('27AAPFU0939F1ZV');
  print('GSTIN check: $check');

  // 2. Work out GST for one line.
  final line = GstCalculator.forLine(
    quantity: 10,
    unitPrice: 500,
    discount: 500,
    gstRate: 18,
    kind: SupplyKind.intraState,
  );
  print(line); // taxable 4500, cgst 405, sgst 405, total 5310

  // 3. Build an invoice. These GSTINs are made-up test values.
  final invoice = EInvoice(
    documentNumber: 'INV/2026-27/0001',
    documentDate: DateTime(2026, 11, 2),
    seller: Party(
      gstin: '24AAAAA0000A1Z8',
      legalName: 'Sample Traders',
      address1: '12 CG Road',
      location: 'Ahmedabad',
      pincode: 380009,
    ),
    buyer: Party(
      gstin: '24BBBBB1111B1ZT',
      legalName: 'Demo Electronics',
      address1: '5 Ring Road',
      location: 'Surat',
      pincode: 395003,
    ),
    items: const [
      InvoiceItem(
        description: 'Wireless Mouse',
        hsnCode: '847160',
        quantity: 10,
        unit: 'NOS',
        unitPrice: 500,
        discount: 500,
        gstRate: 18,
      ),
    ],
  );

  // 4. Check it before sending it anywhere.
  final problems = invoice.validate();
  print(problems.isEmpty ? 'No problems found.' : problems.join('\n'));

  // 5. This JSON is what you send to the IRP (directly or through a GSP).
  print(const JsonEncoder.withIndent('  ').convert(invoice.toJson()));
}