Product architecture

How BidBosna works

A transparent look at our auction engine, bidding rules, notification fan-out, and commission logic.

End-to-end auction flow

Seller lists item

→

Browse & watch

→

Place bid

→

Bid validated

→

Outbid fan-out

→

Auction closes

→

Winner + payout

Authentication

Email + password
Role-based access (Bidder, Seller, Admin)
Session via signed JWT (15m) + refresh

Bidding engine

Validates increment ≥ admin-set minimum
Rejects seller self-bid
Atomic update + bid history append
WebSocket fan-out to viewers

Notifications

Outbid, won, lost, ending soon, new bid
In-app + email channels
Queue-backed with retries

Data layer

PostgreSQL primary
Redis for live bid state
S3-compatible image storage

Admin controls

Suspend/delete users
Remove listings
Tune commission, increments, durations

Performance

Edge cache for browse pages
Realtime bid updates < 250ms
CDN-delivered images

Bidding rules engine

Bid validation pipeline

1Authenticate user and load auction by ID
2Reject if auction.status ≠ active OR auction.endsAt ≤ now
3Reject if bidder.id == seller.id
4Reject if amount < currentBid + minIncrement
5Begin transaction → append bid → update currentBid
6Publish outbid event for previous leader
7Publish new_bid event to seller + viewers
8Commit + return updated auction snapshot

Auction closure

when (auction.endsAt reached):
  IF bids.length == 0:
    auction.status = "ended_no_sale"
  ELSE:
    winner = bids[0].user        // highest
    auction.status = "ended"
    commission = winner.amount
                 * settings.commissionPct
                 / 100
    payouts.create({
      seller: auction.seller,
      gross: winner.amount,
      fee: commission,
      net: winner.amount - commission
    })
    notify(winner, "won")
    notify(seller, "sold")
    notify(losers, "lost")

Commission model

Default fee

Adjustable by admin

Range

5–10%

Recommended band

Applied

On close

Calculated atomically