What is this JSON validator & diff tool?
A free, browser-based tool that validates JSON and compares two JSON documents. Paste a single document to check whether it is well-formed — invalid JSON is reported with a clear message plus the line and column where parsing failed. Or switch to diff mode and paste two documents to see exactly which keys were added, removed, or changed, each labelled with its JSON path (e.g. a.b[0].c). Everything runs locally in your browser, so your data is never uploaded.
How to use it
- Choose a mode: “Validate one” to check a single document, or “Diff two” to compare A and B.
- Paste your JSON. Validation runs live as you type.
- In validate mode, read the valid badge (with type and key/item count) or the line/column error.
- In diff mode, review the added / removed / changed lists, then copy the report.
Common use cases
- Debugging an API response or config file that won't parse — find the exact line and column.
- Reviewing what changed between two versions of a config, fixture, or payload.
- Verifying a hand-edited JSON file before committing or deploying it.