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Know Your Buy
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Check a used laptop before you pay.

Run Know Your Buy from a USB stick on the seller's laptop. In about 8 minutes it tests the battery, storage, processor, graphics, memory and fan, then tells you to buy, negotiate or walk away.

Download for WindowsSee a sample report
  • Free
  • No install
  • Works offline
  • Windows 10 and 11

Know Your Buy report

Intel Core i5-8350U, 16 GB RAM, 512 GB SSD

Sample
  • CheckBatteryAbout 2.5 h of use, not 4 h like new61% health
  • OKStorageNo bad sectors, normal speed93% life left
  • OKProcessorStayed at full speed under load86 °C peak
  • OKMemoryNo errors found16 GB
  • OKFanSpeeds up under loadWorking

Ask for about ₹3,000–5,000 off for a new battery.

Good for

  • College & office: Good
  • Coding: Good
  • Video editing: Okay
  • Gaming: Not a fit
Sample Know Your Buy report. Verdict: Negotiate. Ask for about ₹3,000–5,000 off for a new battery.

Know Your Buy at a glance

What it is
A free portable app that tests a used laptop's hardware and gives a plain verdict: Buy, Negotiate or Walk away.
Who it's for
Used-laptop buyers, mostly in India, meeting a seller in person. No technical knowledge needed.
Price
Free for buyers.
Runs on
Windows 10 (1809 or newer) or Windows 11, 64-bit. Mac: macOS 13 Ventura or newer, Apple Silicon and Intel.
Install
None. Copy one file to a USB stick and run it on the seller's laptop. Clean up & Exit removes everything it created.
Time
About 8 minutes for Run All. Optional 1 to 5 minute stress test.
Internet
Not needed. Nothing is uploaded.
Tests
Battery health, storage health and speed, processor benchmark and overheating, graphics, memory, fan (where exposed).
Output
Verdict, Good / Okay / Bad rating for college & office, coding, video editing, gaming, confidence per result, repair cost estimates, PDF report saved to the USB stick.
Not yet
guided checks for the screen, keyboard, speakers, webcam and ports; spotting faked specs, like a processor name edited in Windows; BIOS lock and Windows activation checks; a fair price estimate for the laptop.

A 15-minute look can't tell you what's wearing out inside.

Sellers aren't always lying. Often they don't know either. Know Your Buy measures it.

  • “Battery is perfect, it lasts all day.”

    The battery holds 58% of its original charge. Expect about 2 hours away from the plug.

  • “Hardly used. The SSD is like new.”

    The drive has been powered on for 14,200 hours and has started replacing bad sectors.

  • “It never heats up.”

    Under load the processor reaches 99 °C and slows down by 40%. The fan or thermal paste needs work.

Examples. You'll see the real numbers for the laptop in front of you.

How it works

  1. 1

    Copy Know Your Buy to a USB stick

    Do this at home. It's one file, about 72 MB. Nothing to install.

  2. 2

    Run it on the seller's laptop

    Plug in the stick, open Know Your Buy and press Run All. It takes about 8 minutes and tells you when to unplug the charger.

  3. 3

    Read the verdict

    Buy, negotiate or walk away, with a plain reason for each. Save the PDF report to your stick, then press Clean up & Exit.

What Know Your Buy checks

How each check works

  • Battery

    How much charge the battery still holds and how many times it has been charged.

    Real hours of use, and a replacement price estimate when it's worn.

  • Storage

    SSD or hard-drive health counters, plus real read and write speed.

    Whether the drive is wearing out. The speed test writes at most 1 GB and deletes it.

  • Processor

    A minute at full load while it watches every core's temperature and speed.

    Overheating and slowing down, which usually means dried thermal paste or a clogged fan.

  • Graphics

    Every graphics chip in the laptop under load: Intel, AMD and NVIDIA.

    Crashes, calculation errors and overheating.

  • Memory

    Writes and checks test patterns across the RAM, up to about 2 minutes.

    Faulty memory, which causes random crashes.

  • Fan

    Whether the fan speeds up when the laptop gets hot.

    A dead or stuck fan. Skipped on laptops that hide their fan sensor.

  • Stress test

    Processor and graphics at 100% together for 1, 3 or 5 minutes.

    Problems that only show up when the laptop works hard for a while.

  • Specs

    Model, processor, graphics, RAM size and speed, and drives in one place.

    What you're actually buying, without digging through Windows settings.

Every result comes with a confidence level, High, Medium or Low, because some laptops report their numbers badly and some counters can be reset.

One clear answer at the end

  • Buy

    No serious problems found. All that's left is agreeing on the price.

  • Negotiate

    It works, but something will cost money soon, like a worn battery or an overheating processor. Use the report to ask for less.

  • Walk away

    Something is failing: memory errors, a dying drive, or crashes under load.

And what the laptop is good for

A laptop can be fine for college but too slow for editing. Know Your Buy rates it for each use:

  • College & office
  • Coding
  • Video editing
  • Gaming

Safe to run on someone else's laptop

Know Your Buy asks for administrator rights because reading temperatures and drive health needs them. Here's what it does with them, and what it doesn't.

Show the seller what Know Your Buy does
  • Nothing gets installed. Know Your Buy runs from your USB stick.
  • The storage test writes at most 1 GB into free space and deletes it straight after.
  • It doesn't open, read or change anyone's files.
  • No internet needed. Nothing is uploaded.
  • Clean up & Exit removes everything Know Your Buy created on the laptop.

Coming next

Not in the current version yet.

  • Guided checks for the screen, keyboard, speakers, webcam and ports
  • Spotting faked specs, like a processor name edited in Windows
  • BIOS lock and Windows activation checks
  • A fair price estimate for the laptop

Questions

Read all questions
  • Is Know Your Buy free?

    Yes. Know Your Buy is free for buyers.

  • Does it need internet?

    No. Everything runs on the laptop, and nothing is uploaded.

  • Will it work on the seller's laptop?

    Windows 10 (version 1809 or newer) and Windows 11, 64-bit, plus a Mac version for Apple Silicon and Intel Macs on macOS 13 or newer. On Windows, the seller may need to approve administrator access with their password; on a Mac no password is needed.

  • Can the results be wrong?

    Some laptops report their numbers badly, and some counters can be reset. Every result shows a confidence level, High, Medium or Low, so you know which ones to trust.

Take it to your next laptop meeting.

Put Know Your Buy on a USB stick tonight. It's free and takes a minute.

Download for WindowsRead the buyer's guide