Anti-Sniping (Soft Close)
Prevents last-second bids from stealing auctions by automatically extending the auction window when a bid lands in the final N seconds.
How it works
Configure two values per auction:
| Field | Default | Effect |
|---|---|---|
| Anti-snipe window | 60 s | Trigger zone — last N seconds of the auction |
| Anti-snipe extension | 120 s | Add N seconds when triggered |
When a bid lands inside the window, the engine extends end_date by the extension amount and increments total_extensions. The auction continues until bidding stops outside the window for the full extension period.
Original end: 18:00:00
Window: 60 s
Extension: 120 s
Bid at 17:59:30 → end = 18:01:30 (extended)
Bid at 18:00:30 → end = 18:02:30 (extended again)
No bid 18:01–18:02:30 → ends at 18:02:30 (final)
Per-auction or global
| Where | Effect |
|---|---|
| Per-auction fields (Add Auction → Schedule) | Highest priority |
Global defaults (wkafw_snipe_window, wkafw_snipe_extension) | Used when auction fields are 0 |
Max-extension cap
To prevent runaway auctions:
| Field | Default | Effect |
|---|---|---|
| Max extension cap | 0 (unlimited) | Total cumulative extension cap (in seconds) |
When total_extensions × extension ≥ max_extension, anti-snipe stops triggering — final bids no longer push the end date.
For a typical 1-hour auction:
| Cap | Behavior |
|---|---|
0 | Unlimited (default — auction can run forever) |
1800 (30 min) | Max 30 min beyond original end |
3600 (1 hr) | Max 1 hr — typical "soft cap" |
When anti-snipe does NOT apply
| Auction type | Reason |
|---|---|
| Sealed | Bids hidden — no "last seconds" anyone can target |
| Penny | Format already extends per-bid |
| Dutch | First-accept wins — no "last second" concept |
Bidder UX
When anti-snipe triggers, the front-end:
- Updates the countdown to the new
end_date - Shows a banner: "Auction extended +120s due to last-second bid"
- Plays a sound (if
wkafw_sounds_default = yes) - Re-rendres bid form with current state
The previous high bidder receives an Outbid email immediately.
Configuration recommendations
| Auction value | Window | Extension | Cap |
|---|---|---|---|
| Low (< $50) | 30 s | 60 s | 600 (10 min) |
| Mid ($50–$500) | 60 s | 120 s | 1800 (30 min) |
| High (> $500) | 120 s | 300 s | 3600 (1 hr) |
| No-cap luxury | 300 s | 600 s | 0 (unlimited) |
Higher-stakes auctions deserve longer windows + extensions to prevent serious bidders from getting sniped by automation.
Anti-snipe and proxy bidding
Proxy auto-bids interact with anti-snipe naturally:
- Late manual bid → triggers extension
- Proxy bid auto-fires to defend → may also trigger another extension
- Continues until proxy max is hit OR no new bids land in the extended window
The total auction duration can grow significantly if proxy maxes are high. Use the max extension cap to bound this.
Trigger logic
Pseudocode:
Reporting
Reports → Auction details show:
- Total extensions per auction
- Average extension count by auction type
- Auctions hitting the max cap
- Median final-bid timing (sniping pattern)
Edge cases
| Scenario | Behavior |
|---|---|
Bid lands at exactly end_date - window | Triggers (inclusive boundary) |
Bid lands at end_date + 0.001 (past end) | Rejected — auction ended |
| Cap reached, bid still placed | Bid accepted, no further extension |
| Anti-snipe disabled (window = 0) | Hard-end at original end_date |
| Server clock drift | Use UTC; sync NTP — drift causes false triggers |
Common questions
"Can I disable anti-snipe per auction?"
Set the window to 0. The trigger condition (seconds_left ≤ 0) is never true, so no extension fires.
"My auction extended 50 times — that's too much."
Set a max_extension cap. After cumulative extensions hit the cap, anti-snipe stops triggering and the auction can hard-end.
"I want fairer-than-anti-snipe — every bid extends by 5 minutes."
Set window equal to extension (e.g. both 300). Every bid in the last 5 minutes adds 5 minutes. Standard practice for live-stream auctions.