H2testw Download: How to Detect Fake SD Cards & Flash Drives: Buying flash storage online can be risky. Many online marketplaces are flooded with counterfeit memory cards and USB drives that claim to have massive storage capacities but actually hold very little data.
H2testw is a completely free diagnostic tool designed specifically to detect such fraud. It was created by German developer Harald Bögeholz for c’t magazine. To determine your drive’s true capacity, it performs a comprehensive “write-and-verify” test on the device.
H2testw Overview
| Detail | Info |
|---|---|
| Software name | H2testw |
| Current version | v1.4 |
| File format | .exe inside a .zip file |
| Download size | 213 KB |
| Works on | Windows 11, 10, 8, 7, and XP |
| Price | Free (Freeware) |
Why Test Your Drive?
Fake drives use modified firmware. Plug in a fake “512GB” card, and your computer will show 512GB free, even though the real chip inside might only hold 8GB or 16GB.
Once you copy files past that real limit, one of two things happens: the drive throws errors, or it quietly overwrites your older files without telling you. Either way, you lose data.
Running H2testw catches this before it happens. It also flags bad sectors on real drives that are simply wearing out with age.
How to Test a Drive
H2testw fills your drive with test data, then reads it back to check that every byte matches.
- Back up and format. Connect your drive, save any files you want to keep, then quick-format it as exFAT or NTFS.
- Open the tool. Extract
h2testw_1.4.zipand double-clickh2testw.exe. - Switch to English. The app may open in German; click the English option in the top left.
- Select your drive. Click Select target and choose the correct drive letter.
- Start the test. Make sure “all available space” is selected, then click Write + Verify. Leave the drive connected until it’s done.
Testing takes time; larger drives can take a few hours since every sector gets written and checked. This is normal.
Reading Your Results
Once the progress bar reaches 100%, review the final log readout:
- “Test finished without errors” (green status): Your drive is completely genuine, matches its retail packaging, and is safe for everyday data storage.
- “The media is likely to be defective” (red status): Your drive is definitely counterfeit. The log will clearly show the actual capacity limits (e.g., “Data lost: 112 GB”), proving that the chip inside is significantly smaller than the stated capacity.
Using H2testw on Mac or Linux
H2testw itself only runs on Windows. If you’re not on Windows:
- Mac: Use F3XSwift, a free Mac app that runs the same write-and-verify test.
- Linux: Use F3 (Fight Flash Fraud), a built-in command-line tool. Run
f3writefollowed byf3readto get the same result.