Small tools that solve real problems
Test your keyboard, mic and screen, work out circuits, or challenge your reflexes. Free, private, no sign-up.
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Your device right now
Measured live in this tabEach bar is one frame your screen drew.
Press any key. Each key you press shows up here. Open the keyboard tester to check every key.
Most popular tools
Open one and get an answer in seconds.
All 25 tools
Grouped by what they help you do.
Device Tests
Check your keyboard, mouse, microphone, webcam, speakers, screen and controller.
Keyboard Tester
Find dead, stuck or double-typing keys and check ghosting.
Mouse Tester
Test every button and the wheel, and detect double-click faults.
Microphone Test
See a live volume meter and record a clip to hear yourself.
Webcam Test
Live preview with resolution, frame rate and snapshots.
Left/Right Speaker Test
Check left/right channels, stereo and bass-to-treble range.
Dead Pixel Test
Fill the screen with solid colors to find dead or stuck pixels.
Refresh Rate Test
Find out if your screen really runs at 60, 144 or 240 Hz.
Gamepad Tester
Check buttons, triggers and analog stick drift on any controller.
Electrical Calculators
Ohm's law, power, resistors, LEDs, voltage drop, wire sizes, batteries and more.
Ohm's Law Calculator
Enter any two of V, I and R to get the third, plus power.
Electrical Power Calculator
Convert between watts, volts, amps and ohms, including 3-phase.
Resistor Color Code Calculator
Decode 4, 5 and 6 band resistors, or find the bands for a value.
LED Resistor Calculator
Pick the right series resistor and wattage for any LED.
Series & Parallel Resistor Calculator
Total resistance of any number of resistors in series or parallel.
Voltage Drop Calculator
Check cable voltage drop and find the right wire size.
AWG to mm² Wire Gauge Converter
Convert AWG ↔ mm² and diameter, with a full gauge chart.
Battery Runtime Calculator
How long a battery lasts, or what size you need.
Capacitor Code Calculator
Decode codes like 104 or 4n7 into pF, nF and µF.
kWh to Joules Energy Converter
Convert kWh, J, Wh, kcal, BTU, therms and more.
Games & Skill Tests
Typing speed, reaction time, click speed, aim training, memory, spin wheel and dice.
Typing Speed Test
Measure your words per minute and accuracy.
Reaction Time Test
Click when it turns green and measure your reflexes in ms.
Click Speed Test (CPS)
How many clicks per second can you do?
Aim Trainer
Hit targets fast to train mouse speed and accuracy.
Memory Game
Flip cards and find all the matching pairs.
Spin the Wheel
Random name picker wheel for classes, giveaways and decisions.
Dice Roller
Roll d4 to d100 with modifiers, for board games and RPGs.
No tools match your search. Try a shorter word, like “mic” or “volt”.
Built to be useful, then get out of your way
Every tool opens instantly, runs in your browser and never asks for an account.
Free, no sign-up
Every tool works instantly. No accounts, no downloads, no trials.
Private by design
Tools run in your browser. Camera, microphone and everything you type stay on your device.
Works everywhere
Built to be fast on phones, tablets and computers, in light or dark mode.
Formulas shown
Calculators show the formula they use, so you can check every result.
Questions people ask
Are these tools really free?
Yes. Every tool is completely free to use, with no sign-up, no limits and no paid version. The site is supported by ads.
Do you store my data?
No. Tools run in your browser, so the values you enter and the audio or video from device tests stay on your device. See our privacy policy for details.
Do the tools work on my phone?
Yes. All tools work on phones and tablets. A few tests, such as the keyboard and mouse testers, are naturally most useful on a computer.
Can I suggest a new tool?
Please do. Send us a message with your idea. New tools are added regularly.