wasmedge validate CLI

After installation, users can execute the wasmedge validate command.

The wasmedge validate command loads a WebAssembly module and runs the validation phase, checking that the module conforms to the WebAssembly specification. It does not instantiate or execute the module. This is useful for verifying correctness of a WASM binary before deployment or execution.

$ wasmedge validate -h
USAGE
   wasmedge validate [OPTIONS] [--] WASM_OR_SO

...

Options

The options of the wasmedge validate command are as follows.

1. -h|--help: Show the help messages. Will ignore the other arguments below.
2. (Optional) --log-level: Set logging level. Valid values: off, trace, debug, info, warning, error, fatal. Default is info.
3. (Optional) --forbidden-plugin: List of plugins to ignore.
4. (Optional) WebAssembly proposals:
   • Use --wasm-1 to set the environment as WASM 1.0 standard. This standard includes the following proposals:
     • Import/Export of Mutable Globals
   • Use --wasm-2 to set the environment as WASM 2.0 standard. This standard includes the WASM 1.0 and following proposals:
     • Non-Trapping Float-to-Int Conversions
     • Sign-Extension Operators
     • Multi-value
     • Bulk Memory Operations
     • Reference Types
     • Fixed-width SIMD
   • Use --wasm-3 to set the environment as WASM 3.0 standard (Currently default since 0.16.0). This standard includes the WASM 2.0 and following proposals:
     • Tail call
     • Extended Constant Expressions
     • Typed-Function References
     • Garbage Collection
     • Multiple Memories
     • Relaxed SIMD
     • Exception Handling
     • Memory64 (currently not implemented)
   • Use --disable-import-export-mut-globals to disable the Import/Export of Mutable Globals proposal (Default ON).
   • Use --disable-non-trap-float-to-int to disable the Non-Trapping Float-to-Int Conversions proposal (Default ON).
   • Use --disable-sign-extension-operators to disable the Sign-Extension Operators proposal (Default ON).
   • Use --disable-multi-value to disable the Multi-value proposal (Default ON).
   • Use --disable-bulk-memory to disable the Bulk Memory Operations proposal (Default ON).
   • Use --disable-reference-types to disable the Reference Types proposal (Default ON).
   • Use --disable-simd to disable the Fixed-width SIMD proposal (Default ON).
   • Use --disable-tail-call to disable the Tail call proposal (Default ON).
   • Use --disable-extended-const to disable the Extended Constant Expressions proposal (Default ON).
   • Use --disable-function-reference to disable the Typed-Function References proposal (Default ON).
   • Use --disable-gc to disable the Garbage Collection proposal (Default ON).
   • Use --disable-multi-memory to disable the Multiple Memories proposal (Default ON).
   • Use --disable-relaxed-simd to disable the Relaxed SIMD proposal (Default ON).
   • Use --disable-exception-handling to disable the Exception Handling proposal (Default ON).
   • Use --enable-threads to enable the Threads proposal (Default OFF).
   • Use --enable-component to enable the Component Model proposal (Default OFF, loader phase only).
   • Use --enable-all to enable ALL proposals above.
5. Input WASM file (/path/to/wasm/file).

Example

Validating a correct module

We created the hand-written fibonacci.wat and used the wat2wasm tool to convert it into the fibonacci.wasm WebAssembly program. It exported a fib() function which takes a single i32 integer as the input parameter.

You can run:

wasmedge validate fibonacci.wasm

The output will be:

[2026-03-24 02:07:35.939] [info] Validation succeeded.

The exit code will be 0.

Validating an invalid module

We created the hand-written bad_validate.wat and used the wat2wasm tool to convert it into the bad_validate.wasm WebAssembly program. This module intentionally contains a type mismatch to demonstrate validation failure.

You can run:

wasmedge validate bad_validate.wasm

The output will be:

[2026-03-24 02:08:49.475] [error] validation failed: type mismatch, Code: 0x202
[2026-03-24 02:08:49.475] [error]     Mismatched value type. Expected: i32 , Got: i64
[2026-03-24 02:08:49.475] [error]     In instruction: end (0x08) , Bytecode offset: 0x00000026
[2026-03-24 02:08:49.475] [error]     At AST node: expression
[2026-03-24 02:08:49.475] [error]     At AST node: code segment
[2026-03-24 02:08:49.475] [error]     At AST node: code section
[2026-03-24 02:08:49.475] [error]     At AST node: module

The exit code will be 1.