When a page misbehaves on a phone and nowhere else, you need its console, and the phone doesn’t show it. Mobile Dev Browser is a browser that captures console.* output, uncaught errors and unhandled promise rejections as you browse, so you can see what went wrong where it went wrong.

Viewing logs is free. A one-time purchase unlocks copying and exporting them to other apps.

Everything you browse and every log it captures stays on your device unless you choose to share it.