Ask HN: Is there a web app to inspect network requests from any device?

Desktop browsers let you inspect network traffic via a developer console. For mobile devices you can install software like Charles proxy onto your local computer and proxy HTTP and HTTPS traffic from your phone through that computer and inspect there.

Is there a web app that does what Charles proxy does? If not, why? Would a web proxy that allows developers to see network requests sent by their phones or any other device that doesn't have a developer console be useful?

Would people pay for this?