Why fake drives are dangerous
A counterfeit USB stick or SD card has its controller reprogrammed to report a big capacity — 256GB, 1TB, 2TB — while the actual memory chip inside is a fraction of that. Everything looks fine at first. Then, once you write past the real size, the drive silently wraps around and overwrites your earliest files. You usually don't find out until the photos or backups you needed are already gone.
How the test works
The Drive Integrity & Capacity Test writes uniquely identifiable markers across the drive's entire claimed capacity, then reads them all back and verifies each one. A genuine drive returns every marker intact. A fake starts returning corrupted or wrong data past its true size — and the test reports exactly where the real capacity ends.
A Mac & Windows alternative to h2testw and F3
The classic tools for this are h2testw (Windows-only) and F3(command line). Cinder does the same full write-and-verify check with a simple interface, on both macOS and Windows, and it's free — no terminal, no license. If you searched for an “h2testw for Mac,” this is it.
Already lost files to a fake drive?
If a counterfeit drive already overwrote your data, some of it may still be recoverable. Cinder's main job is recovering deleted and overwritten files — scan and preview what's left for free, and only pay if you want to save it back. See how Cinder compares to Recuva if you're coming from Windows.
Common questions
How do I test if a USB drive or SD card is fake?
Write real data across the full claimed capacity and read it back. A genuine drive returns everything; a fake returns corrupted data past its true size. Cinder's test does this for you and shows the real usable capacity.
Is there an h2testw alternative for Mac?
Yes — this test runs on macOS (and Windows) with a simple interface, and it's free.
Will testing erase my files?
A full capacity test writes across the drive, so run it on an empty or formatable drive — ideally right after purchase.