A free online JSON viewer for large payloads

Use the browser find shortcut on the output pane. Because every value is on its own line with its full path, a text search lands you on the exact node instead of the first brace near it.

No, and that is deliberate. Collapsing works well for browsing a small document, and badly for finding one field in a large one. A flat searchable listing is faster for the second case.

Up to a few megabytes comfortably. Output is capped at two thousand lines so the tab stays responsive; beyond that, narrow the payload before pasting.

Yes. Everything runs in the browser, so an API response with real customer data never leaves your machine.

You get the line, column and offending character rather than an empty pane, so a viewer doubles as a quick syntax check.