LLM JSON Output Validator
Paste raw LLM output — even with markdown fences or prose around it — and this tool recovers the JSON, tells you which recovery stage worked, and optionally validates it against your expected JSON Schema. Everything runs in your browser.
| Path | Problem | Expected | Got |
|---|
About this tool
Models in "JSON mode" still wrap output in markdown fences or chat around it more often than you'd like. This tool mirrors the recovery pipeline real production code uses: try a direct JSON.parse, then strip ```json fences and retry, then fall back to bracket-matching salvage — find the first { or [ and scan to its matching close, respecting strings and escapes. It reports honestly which stage succeeded, so you know how mangled the output was. The schema check covers a practical draft-07 subset (type, required, properties, items) — enough to catch missing and mistyped fields, not a full validator.
Your data never leaves the page — there is no server, no upload, and no tracking of tool inputs.