How online auctions work
Online auctions take the familiar logic of the saleroom — competitive bidding against a deadline — and run it on software so buyers can take part from anywhere. Here's how the mechanics actually work, from the first bid to settlement, and how the main auction types differ.
By the BidWright team · Auction software studio
The basic idea
An auction is simply a way to find the market price of something by letting buyers compete. A seller lists a lot (the item for sale), buyers place bids, and when the auction closes the lot goes to the winning bid — provided it meets any reserve (a hidden minimum the seller will accept). Online, all of this happens on a website or app instead of in a physical room, which means the pool of buyers is far larger.
How bidding works
Two features do most of the heavy lifting in a well-built online auction:
Proxy bidding
You set the maximum you're willing to pay and the system bids for you in small steps, only as much as needed to stay in front. You might set R50,000 and still be winning at R32,000 if nobody pushes you. It rewards your true valuation, not your reflexes.
Soft close (anti-sniping)
If a bid lands in the last moments, the closing time extends by a short window. That stops "sniping" — winning by bidding at the final second — so the genuine highest bidder takes the lot.
Increments (the minimum step between bids) are usually set automatically by a bid ladder, so the jumps stay sensible as the price climbs. Bidders can watch lots, get outbid alerts, and bid from a phone.
The main types of online auction
"Auction" covers several different mechanisms. The right one depends on what you're selling and what you want to optimise for. We cover the differences in detail in types of auctions explained, but in short:
- Timed / English — the classic ascending auction; the highest bid at close wins.
- Reverse / Dutch — the price starts high and falls until someone buys; fast and great for clearance.
- Sealed bid — bids stay hidden until close; used for tenders and discreet, premium sales.
- Live (automated) — a software auctioneer runs a real rostrum cadence: going once, going twice, sold.
Registration, deposits and trust
Because money changes hands, serious platforms qualify bidders before they can bid. That usually means registering an account, accepting the conditions of sale, and — for higher-value lots — verifying identity and placing a refundable deposit. Deposits keep bidders genuine and cut bad debt, which matters a lot in vehicle, property and livestock sales.
What happens after the hammer falls
When a lot sells, the platform calculates the total — the winning bid plus any buyer's premium and applicable taxes — issues an invoice, and handles payment through the seller's chosen gateway. The seller's commission and payout are worked out automatically, and the deposit is either applied or refunded. Everything is logged, which gives executors, finance teams and auditors a clean record.
Is it safe and legal?
Yes — a bid is a legal offer, and the winning bid forms a contract on the published conditions of sale that bidders accept at registration. In South Africa, well-run platforms also align data handling with POPIA, keep a versioned terms-acceptance trail, and use role-based access and activity logging. The protections are only as good as the software, which is one reason serious operators prefer a platform built and owned by one team rather than a stack of third-party plugins.