About BidKar

The bill is a gate, not a badge. A seller may upload the original purchase bill and state what it says. Nothing renders until an administrator has checked the document and confirmed the numbers against it. No figure a seller types is ever shown to a buyer on the seller's word alone — which is the opposite of how “originally ₹40,000” usually works online.

The inspection happens against the seller's own declaration. A delivery partner arrives with the twelve statements that seller made about that specific item and checks it line by line. Other platforms inspect against a generic rubric, because a generic rubric is all they have. Here there is an itemised declaration to check against.

Buyers and sellers never see each other. Not as a setting that can be switched off, but because the columns do not exist. There is no phone number anywhere in this database.

Every bid is written by a single database function that takes a lock on the listing row first. Fifty people bidding the same amount in the same instant produces exactly one winner and forty-nine rejections, which is the behaviour a marketplace lives or dies on and the one most likely to be wrong.

Minimum increments scale with price, so a ₹400 lot moves in ₹10 steps and a ₹5,00,000 lot moves in ₹5,000 steps. The bid record is append-only: nothing is ever edited or deleted, because it is the evidence if a result is disputed.

A single Next.js application talking to Postgres through Supabase. Authorisation lives in the database as row-level security policies rather than in application code, so a bug in a page cannot leak something a policy forbids — there would be nothing for it to render.