HearthCardCheck

A counterfeit memory card is a small, genuine card whose controller chip has been programmed to report a much bigger size. Anything written past its real capacity either wraps back over earlier data or simply vanishes, which is why photos and videos silently corrupt weeks after they were saved. HearthCardCheck finds that out before you trust the card with anything.

How it works: the app writes a verifiable pattern across the whole card, stamping every small block with its own exact position, then reads all of it back. On a genuine card every block returns exactly what was written. On a fake, blocks come back wrong, and counting the ones that still match reveals the true, reliable capacity. The verdict is plain: genuine, or fake and here is how much it really holds.

Works with SD cards, microSD cards and USB flash drives - anything Windows can see. Three levels of thoroughness: a quick sample, the first 8 GB, or the whole card verified byte by byte. Along the way it also reports the card's read and write speed and whether it looks healthy or is wearing out, so you learn not only whether the card is genuine but whether it is still worth using.

It can also repair a fake. It does not add space that was never there: it measures the exact real capacity, then lays down a single partition that fits only the genuine memory, so Windows never writes to the fake region again and the card becomes reliable at its true, smaller size. Repairing is destructive, so the app explains exactly what it will do, shows the precise steps, asks Windows for administrator permission, and only proceeds after you confirm.

Important to know: testing erases the card. To give an honest result the app writes across every part of it, so copy off anything you want to keep first. And a card that is genuinely failing, rather than simply counterfeit, may still be unreliable even after a repair.

Everything runs locally. No account, no analytics, no cloud - nothing about the card or its files leaves the computer. Pay once, no subscription. Available in 18 languages, and there is a free trial through the Microsoft Store.