Wasm Wasmtime

This one's for when you need to run WebAssembly outside the browser. It covers the wasmtime runtime from CLI basics through Rust embedding, which is where it gets interesting for production use. The fuel metering section is what you want if you're running untrusted code and need hard limits on CPU consumption. It also walks through the component model and WIT interfaces, which is the newer typed approach to WASM modules rather than raw exports. The WASI preview2 coverage is solid for filesystem and networking APIs. If you're building serverside WASM infrastructure or need to sandbox plugins in a Rust app, this gives you the practical commands and code patterns without the usual WebAssembly evangelism.

skills.sh installs: 532
GitHub stars: 279
last updated: Aug 21, 2026

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Install

$ npx -y skills add mohitmishra786/low-level-dev-skills --skill wasm-wasmtime --agent claude-code

Installs into .claude/skills of the current project.

Files

wasmtime — Server-Side WASM Runtime

Purpose

Guide agents through wasmtime: running WASM modules from the CLI, WASI APIs, the component model with WIT interfaces, embedding wasmtime in Rust applications, fuel metering for sandboxed execution, and debugging WASM with DWARF debug info.

Triggers

"How do I run a WASM file with wasmtime?"
"How does WASI work with wasmtime?"
"How do I embed wasmtime in my Rust application?"
"What is the WebAssembly component model?"
"How do I limit WASM execution with fuel?"
"How do I debug a WASM module in wasmtime?"

Workflow

1. wasmtime CLI

# Install
curl https://wasmtime.dev/install.sh -sSf | bash

# Run a WASM module
wasmtime hello.wasm

# Run with WASI arguments
wasmtime prog.wasm -- arg1 arg2

# Pre-open directories (WASI filesystem sandbox)
wasmtime --dir /tmp::/ prog.wasm    # map host /tmp to WASI root

# Pass environment variables
wasmtime --env HOME=/home/user prog.wasm

# Invoke specific exported function
wasmtime run --invoke add math.wasm 3 4

# Inspect exports
wasmtime explore math.wasm    # interactive explorer
wasmtime inspect math.wasm    # show all exports/imports

SKILL.md on GitHub