cloudflare-workers-multi-lang

cloudflare-workers-multi-lang is a skill for Claude Code from secondsky/claude-skills. It costs 45 tokens per session (1,322 once invoked), scanned A, original, MIT.

A guide to building Cloudflare Workers with Rust, Python, or WebAssembly, a portable format for running compiled code. It explains when to use each language for general applications, data and machine-learning work, or demanding computation.

In plain words
What is it for?
Use it when writing Workers outside JavaScript or TypeScript, adding WebAssembly modules, or moving performance-critical processing to Rust or WebAssembly.
Why use it?
It helps choose a suitable language and resolve issues such as missing dependencies, invalid WebAssembly modules, and CPU or memory limits.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the cloudflare-workers plugin — 10 skills, 5 commands shipped together

Good fit Use it when writing Workers outside JavaScript or TypeScript, adding WebAssembly modules, or moving performance-critical processing to Rust or WebAssembly.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/secondsky/claude-skills/cloudflare-workers-multi-lang
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add secondsky/claude-skills --skill cloudflare-workers-multi-lang
Clone the repo
git clone --depth 1 https://github.com/secondsky/claude-skills

Made for: Claude Code.

Or install cloudflare-workers, the plugin that ships this one along with the rest of its 10 skills, 5 commands.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cloudflare-workers-multi-lang

README.md
[![agentmods](https://agentmods.dev/badge/skills/secondsky/claude-skills/cloudflare-workers-multi-lang.svg)](https://agentmods.dev/skills/secondsky/claude-skills/cloudflare-workers-multi-lang)
Your own site
<a href="https://agentmods.dev/skills/secondsky/claude-skills/cloudflare-workers-multi-lang"><img src="https://agentmods.dev/badge/skills/secondsky/claude-skills/cloudflare-workers-multi-lang.svg" alt="Measured on agentmods" height="20"></a>
Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,322 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00045 $0.01322
Opus 5 $0.00023 $0.00661
Sonnet 5 $0.00009 $0.00264
Haiku 4.5 $0.00005 $0.00132

Measured 4d ago against content hash d4540ce033cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

cloudflare-workers-multi-lang scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

The scan reads SKILL.md. This mod also ships 6 executable files (scripts/build-rust.sh, scripts/build-wasm.sh, scripts/test-wasm.sh, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

async fn fetch(req: Request, env: Env, _ctx: Context) -> Result<Response> {
plugins/cloudflare-workers/skills/cloudflare-workers-multi-lang/SKILL.md · 187 lines

How it starts

The opening of the file, as written. The whole thing — 187 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Multi-Language Workers Development

Build Cloudflare Workers using Rust, Python, or WebAssembly for performance-critical operations.

Language Comparison

Feature JavaScript/TS Rust Python
Startup Fast Fastest (WASM) Moderate
CPU Perf Good Excellent Good
Memory Higher Lower Higher
Bundle Size Smaller Medium Larger
Type Safety Optional (TS) Strict Optional
Best For General apps CPU-intensive Data/ML

Quick Decision

Need maximum performance? → Rust/WASM
Heavy computation (crypto, image processing)? → Rust/WASM
Data processing, ML inference? → Python
General web apps? → JavaScript/TypeScript

Top 10 Multi-Lang Errors

Error Language Cause Solution
WebAssembly.instantiate() failed Rust Invalid WASM Check wasm-pack build output
Module parse failed: Unexpected token Rust ESM/CJS mismatch Use --target bundler
Cannot find module Python Missing dep Add to pyproject.toml
Out of memory All Large WASM Enable streaming instantiation
Exceeded CPU time limit All Long computation Chunk processing
wasm-bindgen version mismatch Rust Dep conflict Align versions in Cargo.toml
RuntimeError: unreachable Rust Panic in WASM Add proper error handling
TypeError: not a function Rust Missing export Add #[wasm_bindgen] attribute
Python worker startup timeout Python Slow init Minimize imports
SharedArrayBuffer not supported All Security Add COOP/COEP headers

Rust Quick Start

# Install tools
cargo install wasm-pack

# Create project
cargo new --lib my-worker
cd my-worker

# Add to Cargo.toml
cat >> Cargo.toml << 'EOF'
[lib]
crate-type = ["cdylib"]

[dependencies]
wasm-bindgen = "0.2"
worker = "0.3"
console_error_panic_hook = "0.1"

[profile.release]
opt-level = "s"
lto = true
EOF

Read the full file on GitHub · 187 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 187 lines · 45 tokens per session scan A d4540ce033cd

Subscribe to this mod's changes

cloudflare-workers-multi-lang is a skill published in the GitHub repository secondsky/claude-skills (215 stars, last pushed yesterday), licensed MIT. It adds 45 tokens to every session and 1,322 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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