Error coin auctions: misprints and genuine mint errors, searched at once

Error coins, genuine mint mistakes like off-center strikes, doubled dies, wrong-planchet coins, or the well-known "fried egg" undersized flan error, slipped past quality control before entering circulation, and a verified error can be worth many times face value. Because they're accidents, they can turn up in any denomination or country, without warning.

Why error coin lots get missed

A genuine mint error is easy to dismiss as a damaged or worthless coin if you don't recognise it, and a seller who doesn't know what they're holding often lists it as ordinary loose change rather than a genuine error.

One search across every platform: including a numismatic specialist

Auction Bid Assistant's free browser extension searches the-saleroom, EasyLive, Bidspotter, Invaluable, NumisBids, iCollector and LiveAuctionWorld simultaneously, alongside eBay. NumisBids is itself a platform dedicated entirely to coin and banknote auctions worldwide, so a single search here already reaches specialist numismatic sales as well as the general auction houses where mis-catalogued lots hide. Search "error coin," "mint error," "off-center," or a specific denomination and results return across all of them, with images, estimates, current bids where shown, and sale countdowns, sorted by platform in tabs.

Real results for "error coin": genuine misprint and off-center UK coin errors, including a rare minting error 50p, found in one search.

It works by searching from inside your own browser, the same as opening and searching each site yourself, just done in seconds. Nothing is stored on our servers, permissions are minimal, and the extension never places a bid on your behalf.

Alerts: the single most useful feature for error coins

Because a genuine error might only ever be listed once, save a search ("error coin," a specific fault type, or a denomination) and get emailed the moment a new lot matches it, across all covered platforms including eBay and NumisBids, rather than relying on remembering to check each one.

Want to try before installing?

The same search box works on this website with no install at all for eBay, iCollector, LiveAuctionWorld and Featured Auction catalogues, a quick way to see matching error coin lots before adding the rest of the platforms via the extension.

Built for how error coin collectors actually work

Save any lot with one click from search results, export your shortlist as a printable PDF or CSV before a sale, and on the day itself the optional live bridge feeds the auctioneer's asking price into the free bid calculator, so your maximum (with buyer's premium and VAT included) is always in front of you.

Common questions