.wasm QA Fixtures DevTools, Captures & Bundles CC0 Public Domain · CI/CD Safe

Sample .wasm (WASM) Test Files & Edge Cases

Deterministic WebAssembly Binary Module fixtures engineered for automated unit tests, parser fuzzing, and upload validation pipelines. Pull directly in GitHub Actions with immutable SHA-256 verification.

minimalexpect: valid

minimal-add.wasm

41-byte valid WASM v1 binary exporting `add(i32, i32) -> i32`, directly instantiable via `WebAssembly.instantiate()`.

↓ Download (41 B)

SHA-256: f61fd62f57c41269c3c23f360eeaf1090b1db9c38651106674d48bc65dba88ba

Exact: 41 bytes

curl -fsSL https://fileformat.co/fixtures/v1/wasm/minimal-add.wasm -o minimal-add.wasm \
  && echo "f61fd62f57c41269c3c23f360eeaf1090b1db9c38651106674d48bc65dba88ba  minimal-add.wasm" | shasum -a 256 -c

realisticexpect: valid

env-import-memory.wasm

Contains Type, Import, Function, Memory, Export, and Code sections for symbol scanner tests.

↓ Download (80 B)

SHA-256: f6462abef751b355d056c266a6e5d376afb018bd445477af9d9df333fa0f4f47

Exact: 80 bytes

curl -fsSL https://fileformat.co/fixtures/v1/wasm/env-import-memory.wasm -o env-import-memory.wasm \
  && echo "f6462abef751b355d056c266a6e5d376afb018bd445477af9d9df333fa0f4f47  env-import-memory.wasm" | shasum -a 256 -c

edge-caseTruncated Code Sectionexpect: parser_error

truncated-code-section.wasm

WASM binary whose Code section LEB128 byte length exceeds remaining file bytes.

↓ Download (75 B)

SHA-256: a43778279d60ece37b28759e01fc505e73e18e6274db914e148bd8bfdd8b295d

Exact: 75 bytes

curl -fsSL https://fileformat.co/fixtures/v1/wasm/truncated-code-section.wasm -o truncated-code-section.wasm \
  && echo "a43778279d60ece37b28759e01fc505e73e18e6274db914e148bd8bfdd8b295d  truncated-code-section.wasm" | shasum -a 256 -c

Safe-by-Design Client-Side Synthesizer

In-Browser Edge-Case & Malformed Fixture Mutator

Zero Upload · Generated in RAM

Need negative test fixtures for parser fuzzing or upload gateway validation? Mutate minimal-add.wasm directly in your browser without hosting unsafe payloads on public URLs.

1. Base Input Source

Default Fixture: minimal-add.wasm

2. Select Mutation Operator

Tests graceful EOF / footer corruption handling without process panic or OOM.