Edge Runtime Simulator

edge-runtime is a JavaScript/TypeScript library, currently at version 4.0.1, developed by Vercel. It provides a robust, spec-compliant environment for simulating Vercel Edge Functions or any Web-standard compliant JavaScript code within Node.js or a CLI. This enables local development, testing, and debugging of Edge Functions without requiring actual deployment, significantly streamlining the development workflow. The library aims to faithfully replicate the Edge Function environment, offering Web APIs like `fetch`, `Request`, `Response`, and `URL` as globals within its isolated context. It maintains an active release cadence, with major versions typically aligning with Node.js LTS updates or substantial API enhancements, as demonstrated by the v4.0.0 release which raised the minimum Node.js version requirement. Its core differentiation lies in providing a high-fidelity simulation of the Vercel Edge context.