FetchSandbox is a sandbox environment that lets developers and AI coding agents test API integrations without consuming real API quota. It connects to IDEs like Cursor, Claude Code, Windsurf, and VS Code via a single MCP configuration, enabling webhook delivery testing, retry simulation, async workflows, and failure states. Over 70 pre-configured APIs are available, including Stripe, GitHub, Twilio, and OpenAI. Each workflow run produces a verifiable receipt URL that can be shared in pull requests or team communication tools.