CodingPath Visualizer

Paste JSON and a Swift DecodingError string, and see exactly which node in the JSON tree caused the failure.

Usage

1. Paste your JSON payload into the JSON field.
2. Paste the output of String(describing: error) for a DecodingError into the DecodingError field.
3. The tree view highlights the node at the error's codingPath. For keyNotFound errors, the missing key is shown as a ghost entry.

Click any of the built-in examples to see it in action.

Supported error cases

Case	What it highlights
typeMismatch	The value that had the wrong type
valueNotFound	The null where a value was expected
keyNotFound	The parent object, with the missing key shown inline
dataCorrupted	The value that couldn't be parsed

Development

No build step required. Serve site/ with any static server:

python3 -m http.server -d site

Run tests

bun tests/run.js

Requires Bun (Node's fetch doesn't support file:// URLs). Tests can also be run in the browser by opening tests/index.html through a local server.

Regenerate fixtures

The fixtures/ directory is a Swift Package that produces real DecodingError strings by decoding intentionally malformed JSON. To regenerate:

cd fixtures && swift run Fixtures ../site/fixtures