Cloudflare Workers Runtime Apis

A comprehensive reference for the core runtime APIs you'll use in every Cloudflare Workers project. Covers fetch with timeout and retry patterns, streaming transforms for large payloads, crypto operations like SHA-256 and HMAC signing, cache API usage with waitUntil, WebSocket handling through Durable Objects with hibernation, and text encoding. The real value is in the error prevention table that shows you how to avoid the ten most common mistakes, like trying to read response bodies twice or forgetting to set fetch timeouts before hitting the 30 second worker limit. Load this when you're debugging stream locks, setting up caching, or implementing real-time connections.

skills.sh installs: 326
GitHub stars: 248
last updated: Aug 21, 2026

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Install

$ npx -y skills add secondsky/claude-skills --skill cloudflare-workers-runtime-apis --agent claude-code

Installs into .claude/skills of the current project.

Files

Cloudflare Workers Runtime APIs

Master the Workers runtime APIs: Fetch, Streams, Crypto, Cache, WebSockets, and text encoding.

Quick Reference

API	Purpose	Common Use
Fetch	HTTP requests	External APIs, proxying
Streams	Data streaming	Large files, real-time
Crypto	Cryptography	Hashing, signing, encryption
Cache	Response caching	Performance optimization
WebSockets	Real-time connections	Chat, live updates
Encoding	Text encoding	UTF-8, Base64

Quick Start: Fetch API

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    // Basic fetch
    const response = await fetch('https://api.example.com/data');

    // With options
    const postResponse = await fetch('https://api.example.com/users', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${env.API_KEY}`,
      },
      body: JSON.stringify({ name: 'John' }),
    });

SKILL.md on GitHub