The problem
Property auction houses have traditionally run on a patchwork: catalogues as PDFs, legal packs sent out on request, bids taken in the room or by phone, deposits chased by hand and identity checks done on paper. Buyers want to see everything online and bid from anywhere, and the auction house still has to meet its anti-money-laundering duties.
The idea
Landmark Auctions puts the whole sale online for The Landmark Partnership, a UK residential and commercial property auction house. Each lot carries the details buyers actually check (guide and reserve price, lot number, tenure, EPC rating, council tax band, viewings, completion dates), its legal pack, and online bidding. Behind it sits a back office where agents manage their own lots and admins run auctions and assign work.
How it's built
The platform is a Node.js and Express API on PostgreSQL, with Redis and a separate headless Chrome container that gathers public property details when a lot is set up. It runs in Docker on Agile Tech's own server behind Cloudflare. Deposits and commission are taken through Stripe payment intents in pounds, so card details never touch the platform.
Access is role-based, with admin, agent and bidder roles checked in the browser and enforced again at the API. Sign-up records GDPR consent, admin actions are written to an audit log, and the API has rate limiting and security headers.
Fair bidding
Each bid is written inside a database transaction that also marks the current winning bid, so two people can't both believe they're winning. Bids go up in steps of at least £250. Proxy bids, where the platform bids for you up to a limit, are only allowed once a deposit is in place. A bid in the last 30 minutes pushes the finish out to at least an hour away, which takes the point out of last-second sniping.
Identity, timed around the hammer
The most interesting decision was when to check who a bidder is. Checking everyone up front puts people off before they've found a property they care about. So registered users can bid, and identity and anti-money-laundering checks become an obligation the moment someone wins: one per lot and winner, with a deadline, tracked until it's met.
Where it doesn't fit (yet)
The catalogue is live, and the online bidding, deposits and post-win checks are built ahead of the first fully online sale. Deferring checks until after a win lowers the barrier to bidding, but a winner who can't pass them means the lot has to be offered again, which is why deposits matter. And a soft close makes busy auctions run longer, which suits sellers more than impatient bidders.
What I took from it
In regulated transactions, identity is a timing decision. Verify everyone up front and nobody bids; verify nobody and the business is exposed. The design is in choosing the exact moment to check, and making sure the obligation can't quietly slip.