DevTools

Using DevTools

When running your Worker locally using wrangler dev, you automatically have access to Cloudflare’s implementation ↗ of Chrome’s DevTools ↗. DevTools help you debug and optimize your Workers.

Note

You may have experience using Chrome’s DevTools for frontend development. Notably, Worker DevTools are used for backend code and not client-side JavaScript.

Opening DevTools

To get started, run your Worker in development mode with wrangler dev, then open the DevTools in the browser by hitting d from your terminal. Now when you access this worker locally, it can be debugged and profiled with this DevTools instance.

Alternatively, both the Cloudflare Dashboard ↗ and the Worker’s Playground ↗ include DevTools in their UI.

DevTool use cases

DevTools can be used in a variety of situations. For more information, see the documentation:

• Debugging code via breakpoints and logging
• Profiling CPU usage
• Addressing out of memory (OOM) errors

Related resources

• Local development - Develop your Workers and connected resources locally via Wrangler and workerd, for a fast, accurate feedback loop.