A real non-destructive storage capacity and sector integrity verifier for Linux USB flash drives, SD/microSD cards, external SSDs, and mounted folders. A lightweight Linux alternative to H2testw and F3 (Fight Flash Fraud) for detecting counterfeit wrap-around capacity drives and silent bit corruption.

Key features:

• Live mounted filesystem inspector reading /proc/mounts and os.statvfs (device node, mountpoint, filesystem type, total/used/free GiB, and mount flags).
• Non-destructive sequential chunk writer (.scv files synced via os.fsync) embedding 64-bit global byte offsets and deterministic sector patterns into every 512-byte sector.
• Byte-for-byte readback verifier with SHA-256 digest checking and exact first bad sector / wrap-around alias offset detection to expose fake flash drives that overwrite earlier blocks.
• Visual per-chunk Write vs Read MB/s throughput chart, exportable TXT/JSON audit reports, and one-click test file cleanup.

Disclaimer: This project is an independent open-source tool and is not affiliated with, sponsored by, or endorsed by Harald Boegeholz, Heise Medien (c't), or H2testw.