Know the marginbefore the hammer.
PreHammer overlays the listing you're already on — live comps, MOT history, auction premium and a BUY or PASS before you bid.
No card · BCA, Manheim, Copart, AutoTrader, eBay, Gumtree, Marketplace
What you see on every listing
Ford Focus ST-Line · 2021 · 38,400 mi
Ask £12,995 · Grade 2 · 1.5 EcoBoost
Retail (AutoTrader now)
£13,500 – £15,200 · mid £14,300
Margin
| Buy + premium + prep | £13,295 |
| Realistic sell | £14,200 |
| Profit | +£905 |
How it works
Three steps. Same on every site.
No dashboard to learn — it lives on the tab you already have open.
1
Install the extension
Chrome Web Store — paste your API key from the welcome email. Five full appraisals free, no card.
2
Open any listing
BCA, Manheim, Copart, AutoTrader, eBay, Gumtree or Marketplace. Click the PreHammer button on the page you are already on.
3
Read the sheet
Live comps, MOT trail, margin table and a BUY, PASS or DEPENDS — before you bid or message the seller.
Trader & Pro: BCA catalog spread scan ranks a whole results page by retail margin before you deep-dive lots.
The appraisal sheet
Everything you'd scribble on a notepad
One click. Same sections whether you're on an auction lot or a retail ad.
Verdict
BUY, PASS or DEPENDS — first
Not a wall of data. A straight call on whether the lot is worth your hammer, with the reasons underneath.
Retail comps
AutoTrader pulled now
Median, band and days-to-sell for that exact make, model and year — fetched when you click, not from last month's guide.
DVLA + MOT
Plate check and full MOT trail
Make, fuel, tax status and every recorded mileage. Listing says 67k but MOT says 94k? Flagged in red before you bid.
Margin table
Hammer to forecourt maths
Buy price, buyer's premium on auctions, prep, selling costs and a realistic ask — one profit number at the bottom.
Known faults
Expensive surprises, upfront
Model-specific fault list with typical UK repair bands and eBay parts links — DSG, timing belt, EGR, the usual killers.
Pass early. Bid with a number.
Real decisions the sheet is built for.
Vauxhall Corsa 1.2 · 2019 · 67,200 mi
Auction · Grade 3
MOT trail shows 94,100 mi at last test — listing under-reported mileage. Retail mid £7,200. Walk.
Ford Focus ST-Line · 2021 · 38,400 mi
Auction · Grade 2
Clean MOT, no clocking flags. Retail mid £14,300 after premium and prep — est. +£905 margin.
One flip pays for the year
5 free full appraisals to start. Pick a plan when you're buying regularly.
Free trial
5 full appraisals · any listing · no card
Starter
200 appraisals / mo
Side flips & one-offs
- ▪Full sheet on any listing
- ▪Live AutoTrader comps
- ▪DVLA, MOT & clocking check
Trader
500 appraisals / mo
Catalog days & weekly buying
- ▪Everything in Starter
- ▪BCA catalog spread scan
Pro
Unlimited appraisals
Full-time buying desk
- ▪Everything in Trader
- ▪Unlimited catalog scans
Ex VAT · Monthly · Cancel anytime via Stripe · Starter is single-lot only; catalog scan from Trader up
FAQ
What is BCA catalog spread scan?+
On BCA catalog results pages, Trader and Pro plans can rank every lot by retail spread — live AutoTrader median minus BCA estimate. It does not run a full MOT/DVLA appraisal on each lot; click ⚡ on a row for that (one scan each). BCA only — beta, depends on BCA page structure.
What counts as a scan?+
One full appraisal, one scan. Re-opening the same listing uses cache and doesn't count. Allowance resets on the 1st of each month. Catalog spread scan uses separate comp lookups on Trader and Pro.
Does the profit table change for auction lots?+
Yes — on BCA, Manheim and Copart we add buyer's premium and adjust sell-side estimates for auction-bought stock.
How fresh are the AutoTrader comps?+
Pulled live when you click — actual search results for that make, model and year, not a stale price guide.
What if there's no reg plate on the listing?+
Margin and comps still run from the ad text. DVLA/MOT sections stay empty and the verdict flags what's unverified.
Any setup beyond installing the extension?+
Paste your API key from the welcome email. We host DVLA, MOT and comp lookups — you don't configure data feeds.
Can I cancel any time?+
Yes — open the billing portal at prehammer.com/billing with your checkout email. Access continues until the end of your billing period.
Run it on your next lot
Install, open a listing, hit appraise. You'll know if the margin works before you bid.
Chrome Web Store →