Know the marginbefore you bid.
UK vehicle-appraisal Chrome extension with live comps, MOT history and a maximum bid calculated locally from your own costs and target margin.
- PreHammer analyses AutoTrader, eBay and Gumtree listings in one click.
- PreHammer returns BUY, PASS or DEPENDS verdict before you bid.
- PreHammer gives one instant appraisal and four more after email confirmation.
No signup for the first appraisal · No card
What you see on every listing
Ford Focus ST-Line · 2021 · 38,400 mi
Current bid £10,100 · Grade 2 · 1.5 EcoBoost
Retail anchor (8 sold comps)
Lower quartile · £13,500
Margin
| Bid + fee + all costs | £11,150 |
| Retail anchor | £13,500 |
| Projected margin | +£2,350 |
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
Install from the Chrome Web Store and run one appraisal immediately. Confirm your email to unlock four more. 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.
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
UK retail comps pulled now
Median and price band for that make, model and year, fetched when you click from live UK listing data, not a stale guide.
MOT evidence
Mileage trail and MOT history
Recorded mileage from MOT tests is checked against the listing. Listing says 67k but MOT says 94k? Flagged in red before you bid.
Margin table
Your maximum bid, calculated
Your saved buyer fee, prep, transport, selling costs and minimum margin are applied locally. Missing material inputs force DEPENDS.
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
Eight sold comps. A £300 buyer fee plus £750 saved costs leaves £2,350 projected margin; maximum bid £10,950.
Actively buying UK stock?
Bring one live lot to a setup call
We are onboarding 10 founding traders personally at £29/month—only after PreHammer works on your real buying workflow. The concierge pilot includes a 30-minute setup call and direct access; the self-serve plans below do not.
One flip pays for the year
Try one appraisal instantly, then confirm your email for four more. Pick a plan when you're buying regularly.
Free trial
1 instant + 4 after email confirmation · no card
- ▪Full sheet on any listing
- ▪Live UK retail comps
- ▪MOT history & clocking check
Ex VAT · Cancel anytime via Stripe
FAQ
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.
Does the profit table change for auction lots?+
Yes. Save your actual buyer fee in Deal assumptions. PreHammer keeps it in Chrome and applies it to each auction lot instead of guessing a generic premium.
How fresh are the retail comps?+
Pulled when you click from live UK sold and active listing data matched to make, model, year and mileage, not a printed price guide.
What if there's no reg plate on the listing?+
Margin and comps still run from the ad text. Registration-based evidence stays empty and the verdict flags what's unverified.
Any setup beyond installing the extension?+
No setup for your first appraisal. We host MOT and comp lookups. Subscribers paste the key from their checkout email once.
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.
Lost your subscription key?+
Open Account in the footer and sign in with your checkout email. You can copy your key there anytime. If you cannot sign in, use Recover key (email plus last 4 characters of your key).
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 →