Learn Wat - 10 Code Examples & CST Typing Practice Test

WAT (WebAssembly Text Format) is the human-readable, assembly-like syntax used to represent WebAssembly binaries. It allows developers to write, inspect, debug, and understand Wasm modules using a clear, text-based format before compiling to .wasm.

View all 10 Wat code examples →

Simple WAT Module WAT Multiply Module WAT Subtract Module WAT Factorial Module WAT Fibonacci Module WAT Max Module WAT Min Module WAT Even Check Module WAT Odd Check Module WAT Toggle Module

Learn WAT with Real Code Examples

Updated Nov 25, 2025

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Code Sample Descriptions

Simple WAT Module

# wat/demo/add.wat
(module
    (func $add (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.add)
    (export "add" (func $add))
)

A basic WebAssembly Text Format (WAT) module that adds two numbers.

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WAT Multiply Module

# wat/demo/multiply.wat
(module
    (func $multiply (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.mul)
    (export "multiply" (func $multiply))
)

A WAT module that multiplies two numbers.

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WAT Subtract Module

# wat/demo/subtract.wat
(module
    (func $subtract (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.sub)
    (export "subtract" (func $subtract))
)

A WAT module that subtracts two numbers.

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WAT Factorial Module

# wat/demo/factorial.wat
(module
    (func $factorial (param $n i32) (result i32)
        (local $result i32)
        (local.get $n)
        i32.const 1
        i32.le_s
        if (result i32)
        then i32.const 1
        else
        local.get $n
        local.get $n
        i32.const 1
        i32.sub
        call $factorial
        i32.mul
        end)
    (export "factorial" (func $factorial))
)

A WAT module that calculates factorial recursively.

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WAT Fibonacci Module

# wat/demo/fibonacci.wat
(module
    (func $fib (param $n i32) (result i32)
        local.get $n
        i32.const 1
        i32.le_s
        if (result i32)
        then local.get $n
        else
        local.get $n
        i32.const 1
        i32.sub
        call $fib
        local.get $n
        i32.const 2
        i32.sub
        call $fib
        i32.add
        end)
    (export "fib" (func $fib))
)

A WAT module that calculates Fibonacci numbers recursively.

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WAT Max Module

# wat/demo/max.wat
(module
    (func $max (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.gt_s
        if (result i32)
        then local.get $a
        else local.get $b
        end)
    (export "max" (func $max))
)

A WAT module that returns the maximum of two numbers.

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WAT Min Module

# wat/demo/min.wat
(module
    (func $min (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.lt_s
        if (result i32)
        then local.get $a
        else local.get $b
        end)
    (export "min" (func $min))
)

A WAT module that returns the minimum of two numbers.

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WAT Even Check Module

# wat/demo/even.wat
(module
    (func $isEven (param $n i32) (result i32)
        local.get $n
        i32.const 2
        i32.rem_s
        i32.eqz)
    (export "isEven" (func $isEven))
)

A WAT module that checks if a number is even.

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WAT Odd Check Module

# wat/demo/odd.wat
(module
    (func $isOdd (param $n i32) (result i32)
        local.get $n
        i32.const 2
        i32.rem_s
        i32.const 0
        i32.ne)
    (export "isOdd" (func $isOdd))
)

A WAT module that checks if a number is odd.

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WAT Toggle Module

# wat/demo/toggle.wat
(module
    (global $state (mut i32) (i32.const 0))
    (func $toggle (result i32)
        global.get $state
        i32.const 1
        i32.xor
        global.set $state
        global.get $state)
    (export "toggle" (func $toggle))
)

A WAT module that toggles a boolean value between 0 and 1.

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Frequently Asked Questions about Wat

What is Wat?

What are the primary use cases for Wat?

Learning WebAssembly internals. Debugging or inspecting Wasm modules. Creating tiny hand-crafted Wasm binaries. Reverse engineering WebAssembly. Testing Wasm instructions or host bindings

What are the strengths of Wat?

Extremely lightweight and minimal. Perfect for learning WebAssembly internals. Direct control over Wasm structure and instructions. Readable and easy to experiment with. Useful for debugging compiler output

What are the limitations of Wat?

Not suitable for large-scale application development. No high-level abstractions (loops, structs, variables). Verbose for anything beyond small modules. Hard to maintain manually. Manual memory management required

How can I practice Wat typing speed?

CodeSpeedTest offers 10+ real Wat code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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Learn Wat - 10 Code Examples & CST Typing Practice Test

Code Sample Descriptions

Simple WAT Module

# wat/demo/add.wat
(module
    (func $add (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.add)
    (export "add" (func $add))
)

A basic WebAssembly Text Format (WAT) module that adds two numbers.

Let’s Try →

WAT Multiply Module

# wat/demo/multiply.wat
(module
    (func $multiply (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.mul)
    (export "multiply" (func $multiply))
)

A WAT module that multiplies two numbers.

Let’s Try →

WAT Subtract Module

# wat/demo/subtract.wat
(module
    (func $subtract (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.sub)
    (export "subtract" (func $subtract))
)

A WAT module that subtracts two numbers.

Let’s Try →

WAT Factorial Module

# wat/demo/factorial.wat
(module
    (func $factorial (param $n i32) (result i32)
        (local $result i32)
        (local.get $n)
        i32.const 1
        i32.le_s
        if (result i32)
        then i32.const 1
        else
        local.get $n
        local.get $n
        i32.const 1
        i32.sub
        call $factorial
        i32.mul
        end)
    (export "factorial" (func $factorial))
)

A WAT module that calculates factorial recursively.

Let’s Try →

WAT Fibonacci Module

# wat/demo/fibonacci.wat
(module
    (func $fib (param $n i32) (result i32)
        local.get $n
        i32.const 1
        i32.le_s
        if (result i32)
        then local.get $n
        else
        local.get $n
        i32.const 1
        i32.sub
        call $fib
        local.get $n
        i32.const 2
        i32.sub
        call $fib
        i32.add
        end)
    (export "fib" (func $fib))
)

A WAT module that calculates Fibonacci numbers recursively.

Let’s Try →

WAT Max Module

# wat/demo/max.wat
(module
    (func $max (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.gt_s
        if (result i32)
        then local.get $a
        else local.get $b
        end)
    (export "max" (func $max))
)

A WAT module that returns the maximum of two numbers.

Let’s Try →

WAT Min Module

# wat/demo/min.wat
(module
    (func $min (param $a i32) (param $b i32) (result i32)
        local.get $a
        local.get $b
        i32.lt_s
        if (result i32)
        then local.get $a
        else local.get $b
        end)
    (export "min" (func $min))
)

A WAT module that returns the minimum of two numbers.

Let’s Try →

WAT Even Check Module

# wat/demo/even.wat
(module
    (func $isEven (param $n i32) (result i32)
        local.get $n
        i32.const 2
        i32.rem_s
        i32.eqz)
    (export "isEven" (func $isEven))
)

A WAT module that checks if a number is even.

Let’s Try →

WAT Odd Check Module

# wat/demo/odd.wat
(module
    (func $isOdd (param $n i32) (result i32)
        local.get $n
        i32.const 2
        i32.rem_s
        i32.const 0
        i32.ne)
    (export "isOdd" (func $isOdd))
)

A WAT module that checks if a number is odd.

Let’s Try →

WAT Toggle Module

# wat/demo/toggle.wat
(module
    (global $state (mut i32) (i32.const 0))
    (func $toggle (result i32)
        global.get $state
        i32.const 1
        i32.xor
        global.set $state
        global.get $state)
    (export "toggle" (func $toggle))
)

A WAT module that toggles a boolean value between 0 and 1.

Let’s Try →

Frequently Asked Questions about Wat

What is Wat?

What are the primary use cases for Wat?

Learning WebAssembly internals. Debugging or inspecting Wasm modules. Creating tiny hand-crafted Wasm binaries. Reverse engineering WebAssembly. Testing Wasm instructions or host bindings

What are the strengths of Wat?

What are the limitations of Wat?

How can I practice Wat typing speed?

CodeSpeedTest offers 10+ real Wat code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.