Download Know Your Buy

Free for buyers. No installer. Put it on a USB stick and take it to the meeting. One download for Windows laptops, two for Macs (pick the one for the Mac you are testing).

Download for Windows coming soon

Know Your Buy 0.1.0 is being prepared for public download.

Mac · Apple Silicon (M1, M2, M3, M4)Mac · Intel (2018 or newer)

Mac downloads are being prepared alongside the Windows release.

What you need

Windows laptop

Windows: Windows 10 (1809 or newer) or Windows 11, 64-bit
Permission: Someone on the laptop must allow administrator access when Windows asks
USB stick: Any stick with 100 MB or more free, for the app and the reports
Internet: Not needed
Battery test: Needs the laptop's charger, so you can unplug it when asked

MacBook

macOS: macOS 13 Ventura or newer. Apple Silicon (M1 to M4) or Intel Macs from 2018
Permission: None. No admin password is needed on a Mac
USB stick: Formatted as APFS or Mac OS Extended (Disk Utility), 100 MB or more free
Internet: Not needed
First open: A one-time “Open Anyway” in System Settings, explained below

Know Your Buy doesn't run on Linux or Chromebook. Windows laptops with ARM processors (like Snapdragon) can run the Windows version, but slowly and with less accurate speed scores.

Which Mac version?

Macs come with two kinds of chip, and each needs its own build of Know Your Buy.

1
Click the Apple menu, then About This Mac
Top-left corner of the screen.
2
Read the Chip or Processor line
Chip: Apple M1 / M2 / M3 / M4 → download the Apple Silicon version. Processor: Intel → download the Intel version.
3
Not sure which Mac you'll be testing?
Put both on the USB stick. They are small. The Intel version also starts on an Apple Silicon Mac, but its speed scores are too low to trust, and Know Your Buy says so.

Put it on a USB stick

1
Download Know Your Buy
Do this at home, on your own computer. Windows: KnowYourBuy.exe. Mac: open the .dmg and drag KnowYourBuy.app out of it.
2
Copy it to a USB stick
Drag KnowYourBuy.exe or KnowYourBuy.app onto the stick. Nothing else is needed.
3
Take the stick to the meeting
Reports are saved to a KnowYourBuy-Reports folder on the stick, next to the app. The buyer's guide walks you through the meeting.

On a Mac: "Apple could not verify Know Your Buy is free of malware"

macOS shows this for every app that isn't registered with Apple yet. Know Your Buy is safe, but it isn't registered, so you will see it once on each Mac. Allowing it takes 20 seconds.

1
Double-click Know Your Buy, then click Done on the warning
Nothing opens yet. That's expected.
2
Open System Settings → Privacy & Security
Scroll down to the Security section.
3
Next to "Know Your Buy was blocked", click Open Anyway
Confirm with Open Anyway again. On macOS 13 and 14 you can instead Control-click Know Your Buy and choose Open.
4
Done. From now on it opens with a normal double-click on that Mac
The seller's Mac may show the same warning once. Repeat these steps there, or use the tip below.

No warnings at the meeting: macOS marks downloaded files, and that mark travels with the app onto the stick. After copying KnowYourBuy.app to your stick, open Terminal on your own Mac and run xattr -dr com.apple.quarantine /Volumes/YOUR-STICK/KnowYourBuy.app. Know Your Buy then opens on any Mac with a plain double-click. The same steps are in the READ ME FIRST file inside the download.

On Windows: "Windows protected your PC"

Windows shows this blue screen for apps it hasn't seen many times before. Know Your Buy is new, so you may see it.

1
Click More info
It's the small link under the message.
2
Check the app name says KnowYourBuy.exe
If it shows any other name, don't run it.
3
Click Run anyway
Know Your Buy opens.

Only run a copy you downloaded from this site. You can check the file is genuine using the fingerprint in Check your download below.

When Windows asks "Do you want to allow this app to make changes?"

Click Yes. Know Your Buy needs administrator access to read temperatures, fan speeds and drive health. Windows only shows those to administrator apps. (Macs need no password: macOS lets Know Your Buy read them directly.)

If Windows asks for a password, the seller needs to type it. Know Your Buy never sees it. If no one can approve it, Know Your Buy can't run on that laptop, which is worth knowing too.

What Know Your Buy does with administrator access

The optional temperature driver (Windows)

When Know Your Buy starts on Windows, it may offer to install a small driver called PawnIO. It lets Know Your Buy read exact processor temperatures. It's optional.

It's only installed if you agree.
Know Your Buy checks the driver is the genuine, signed file before installing it.
Clean up & Exit removes it again, if Know Your Buy was the one that installed it.
Without it, Know Your Buy still works and judges overheating from how fast the processor keeps working. Those results show a lower confidence.

Check your download

Every copy of Know Your Buy 0.1.0 has the same fingerprint (SHA-256). If yours matches, the file hasn't been changed.

Windows

Right-click the Start button and open Terminal or PowerShell.
Go to the folder with KnowYourBuy.exe and run:
```
Get-FileHash .\KnowYourBuy.exe
```
Compare the long code it prints with this one:

The fingerprint will be published here with the download.

Mac

Open Terminal (Applications → Utilities).

Run one of these, depending on the file you downloaded:

shasum -a 256 ~/Downloads/KnowYourBuy-AppleSilicon.dmg
shasum -a 256 ~/Downloads/KnowYourBuy-Intel.dmg