JSON Crack

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Build me a JSON viewer that draws the document as a graph — and note the core of this one is open source, so the honest starting point is that repository rather than a blank page.

**And the reason to run it yourself is not money.** Pasting an API response into somebody else's web page means pasting whatever was in it: a token, a customer's address, an internal identifier. A local viewer never sends it anywhere, and for anything from a production system that is the whole argument.

STACK
- One static page, or a small local application. No server at all is the point
- A layout library for the graph. Do not write a graph layout algorithm
- The browser's own JSON parser, with a streaming parser for anything large

THE VIEW
- Objects as nodes with their scalar fields listed inside, arrays as branches, references drawn as edges
- **Collapse by default below a depth**, and expand on click. A graph of a large document drawn all at once is a hairball and helps nobody
- Click a node to see its path — `data.items[3].owner.email` — and copy it. That path is what people actually came for, more often than the picture
- Search across keys and values, with matches highlighted in the graph and a list to step through
- A tree view beside the graph, because for a deep narrow document a tree is simply better and pretending otherwise is stubbornness

HANDLING WHAT PEOPLE ACTUALLY PASTE
- A malformed document is the common case. **Say where it broke, with the line and column and the surrounding text** — that error message is more valuable than the graph
- Trailing commas, single quotes, unquoted keys and comments all appear in the wild. Offer to repair them, showing the repair, rather than refusing
- Very large files: parse as a stream, render only what is on screen, and cap the node count with a clear message rather than freezing the tab
- Numbers beyond what a double can hold — a 64-bit identifier — lose precision silently in a normal parse. Detect the shape and keep the original text, or the tool quietly corrupts exactly the field somebody was checking

CONVERTING
- To and from YAML, CSV, and a type definition for the language you use. Generating types from a real response is the feature people use most after viewing
- A JSON Schema inferred from the document, which is a good first draft and should be labelled as a draft
- JSON Path or a query expression evaluated live against the document

EXPORT
- The graph as SVG and PNG at a size worth putting in a document
- The formatted document, and a minified one

PRIVACY, WHICH IS THE FEATURE
- Everything in the browser. No upload, no server round trip, no analytics on the page
- Say so plainly on the page itself, because a person about to paste a production payload is entitled to know before they do it
- If you add saving, save locally by default and make anything shared an explicit, obvious choice

WHAT MATTERS MOST
The error message on a broken document, and never sending the payload anywhere. The first is what the tool is opened for half the time; the second is why it can be opened with something real in the clipboard.