Test Your Custom Keyboard Key Mappings
Build a mapping list, press keys and instantly see the physical key and the output it should produce. Verify remap configurations before you rely on them.
Mapping Verification Features
Everything you need to confirm a keyboard remap configuration
One-Click Capture
Press a key to capture the source, press again to set the target - no typing required
Live Mapping Preview
Each key press shows the physical key, its code and the mapped output side by side
Rule Table
Review every mapping with its target and hit counter to spot duplicates or gaps
Ready Presets
Load common layouts such as WASD to arrows or Caps Lock to Escape in one click
Import & Export
Save rules as JSON and load them again on another device or browser
Fully Local
Key events never leave your browser and no keystrokes are recorded to any server
How to Test Key Remapping
Four steps from an empty rule list to a verified mapping
Add a mapping
Click the capture box and press the key you want to remap, then press the key it should become
Start test mode
Enable test mode so every key press is compared against your rule list
Press your keys
Press each mapped key and confirm the live result shows the expected target output
Export the rules
Download the verified mapping as JSON to keep it as documentation or share it
Browser Compatibility
Keyboard events are handled natively by every modern browser
Chrome
Full SupportFull support including key code capture
Edge
Full SupportFull support on Chromium-based Edge
Firefox
Full SupportFull support with standard key codes
Safari
Full SupportSupported on macOS and iPadOS with a hardware keyboard
Frequently Asked Questions
Common questions about testing keyboard remapping
Does this page actually remap my keys?
No. A web page cannot change system-level keyboard behaviour. This tool verifies the mapping logic, so you can confirm that a remap created with PowerToys, AutoHotkey, Karabiner or a keyboard firmware is set up the way you intend.
What is the difference between a key and a key code?
The key value depends on layout and modifiers (for example 'a' versus 'A'), while the key code identifies the physical position (for example KeyA). Mapping tools usually work with physical codes, which is why both are shown.
Why is a key not detected at all?
Some keys, such as the Windows key, Print Screen or media keys, are intercepted by the operating system before reaching the browser. Remap tools can also swallow keys entirely if a rule is misconfigured.
Can I test layered or chord mappings?
Simple one-to-one mappings are fully supported. For chords, note that this tester records the single key that produced the event, so a chord will appear as its resulting key.
How do I share my mapping with someone else?
Use the export button to download a JSON file, then share it. The import button loads it back into the rule table on any computer.
Are my keystrokes sent anywhere?
No. All key handling is done in your browser. Nothing is logged, uploaded or stored on a server.