Seesaw is a web-based tool Julian and I built for inspecting complex JSON structures, without having to click to expand and collapse folders. You can click a box to zoom to it, or use the arrow keys to navigate around the structure.
The central conceit of Seesaw is that everything is either a bottom-level key-value pair, or a box containing either key-value pairs or other boxes. Every JSON element is drawn onscreen on load, and each associated div is printed nested inside its parent. Bottom-level key-value pairs are colored consistently, so that a
name key is, for example, always red. This, coupled with the tendency of arrays to look visually consistent, makes exploring a complex, nested data structure much easier.
The up and down arrows go up and down a level in the object, and the left and right arrows navigate to siblings.