Billing software for Delhi's neighbourhood shops.

A large share of what fills a Delhi kirana shelf passes through a few old streets. Khari Baoli, at the western end of Chandni Chowk beside Fatehpuri Masjid, has traded since the 17th century and is called Asia's largest wholesale spice market. It deals in spices, nuts, herbs, dry fruits, rice and tea, and supplies buyers across North India, from Jammu and Kashmir to Rajasthan and Madhya Pradesh. The adjoining Gadodia Market, built by merchants in the 1920s, makes the same claim. A little further west, Sadar Bazaar is often called the largest wholesale market in India, selling household goods, toys, imitation jewellery and stationery in bulk.

Fresh produce moves through Azadpur Mandi in North Delhi, which is considered the largest fruit and vegetable market in Asia. Between these markets, a single general store can end up buying masala and dry fruits from Khari Baoli, plastic ware and stationery from Sadar Bazaar, and packaged goods from a distributor, each with its own bill and its own way of packing.

That mix is what makes a Delhi shelf hard to manage. Some items carry a barcode, many loose or locally packed ones do not, and new lines appear after every wholesale trip. Bazaar IQ scans barcodes from the phone camera and finds everything else by name. An item that is not in the catalogue yet can still be billed, so a new product from this week's trip does not hold up the queue. Bulk purchases go into storage (godown) stock and are counted separately from the shelf, which helps when the back room holds three cartons and the shelf only one.

Hindi and English are Delhi's official languages, with Punjabi and Urdu as additional official languages. In the 2011 census about 81.3 percent of the city spoke Hindi, so it is the language most counters run on. Bazaar IQ can be used in Hindi or English, as well as Marathi and Gujarati. Delhi has its own legislature, so for GST it is treated like a state: every GSTIN registered here begins with 07, and a sale within Delhi shows CGST and SGST. Regular dealers print tax invoices with HSN codes and that split. Composition-scheme shops print a Bill of Supply carrying the composition line the law requires, and unregistered shops a plain cash memo. Colony regulars who pay weekly or monthly can buy on khata, which is built into billing and keeps a running balance for each customer.