What Is a Controller Mapping Viewer?
This tool shows every button and axis your controller exposes to the browser, labeled by its raw numeric index, and highlights each one in real time the instant you press it or move a stick. It's built for the practical, slightly technical need of figuring out exactly which index number corresponds to a specific physical button or stick - information that remapping software, emulator configuration files, and custom game input bindings frequently ask for by number rather than by name.
How to Use the Controller Mapping Viewer
- Connect your controller and press any button so the browser detects it.
- Press each button one at a time and note which "B" number highlights green.
- Move each stick and trigger, and note which "A" (axis) numbers respond and by how much.
- Write down the index numbers you need for whatever remapping tool or config file you're working with.
How It Works
This tool reads the standard Gamepad.buttons and Gamepad.axes arrays every
animation frame, displaying each entry's current numeric value alongside its array index - the same index
numbers used internally by the Gamepad API and referenced by many external configuration tools. A button or
axis highlights whenever its value crosses a small activity threshold, making it immediately obvious which
index just responded to your input.
Understanding Your Results
- Each physical button lights up exactly one index consistently - your controller has a clean, standard mapping, which is the expected and most common case for modern controllers.
- A trigger appears as both a button and an axis - common on certain controllers where analog triggers report their pressure both as a button value and a separate axis value simultaneously.
- Index numbers differ from what you expected based on another source - different controllers, and sometimes different browsers, can map the same physical button to a different index; always verify with a live tool like this one rather than assuming a fixed universal standard.
- An index doesn't respond to any input at all - either that slot isn't used by your specific controller model, or that particular button/axis isn't functioning.
Browser Limitations
The Gamepad API attempts to normalize many controllers to a "standard" mapping where possible, but non-standard or less common controllers may report indexes differently between browsers, or may not be recognized as "standard" at all - in which case raw indexes are still shown accurately, just without the conventional standard-layout guarantee.
Common Mistakes to Avoid
- Assuming index numbers are identical across all controller brands - always confirm with a live check like this one rather than assuming a fixed universal numbering.
- Testing with very light button presses - some buttons and triggers report a smooth analog value; a very light touch might not cross the activity threshold used for highlighting here.
- Forgetting triggers can appear on both button and axis lists - check both sections if you're specifically mapping trigger inputs.
Frequently Asked Questions
Why do I need this instead of just looking up a standard controller layout online?
Index numbering can vary between controller models, operating systems, and even browsers, so a live check on your specific setup is more reliable than a generic reference chart.
Why does one trigger show up in both the buttons and axes sections?
Analog triggers on many controllers report their pressure amount as both a button value and a separate axis value at the same time, which is standard Gamepad API behavior for that input type.
Can I use this to actually remap my controller?
This tool only displays raw index information; actual remapping needs to be done in your operating system's controller settings, a dedicated remapping utility, or the specific game or emulator's own control configuration.
Is my controller input data stored or sent anywhere?
No. Everything is read and displayed live in your browser only, and nothing is transmitted or saved.
Why does a button show a decimal value instead of just pressed or not?
Many modern controllers report button pressure as an analog value between 0 and 1, not just a simple on/off state, which is especially common and useful for triggers and pressure-sensitive face buttons.
Conclusion
Whether you're setting up a custom emulator profile or troubleshooting a remapping tool that's asking for specific index numbers, this gives you exact, live-verified answers straight from your own hardware. For overall button and stick health, pair this with the Gamepad Tester.