AI Output Schema Validator
LLMs told to "return JSON" often add code fences, chatty preamble, and trailing commas that break your parser. This tool cleans that output, parses it, and validates it against a JSON Schema — reporting exact violation paths. All locally.
Tool interface
Result
Cleanup steps applied
Schema violations
Introduction
Structured-output prompts still fail in production. This tool reproduces the cleanup you'd otherwise write as brittle regex, then runs a real schema validation so you can trust the parsed result before it reaches your application.
How it works
- Strip markdown code fences and surrounding prose.
- Extract the first balanced
{…}or[…]block. - Apply incremental repairs (trailing commas, comments, single quotes, unquoted keys), retrying
JSON.parseafter each. - Validate against your schema and list violations with JSON paths.
Privacy
All parsing and validation run locally. No upload, no account, no API key.
Limitations
- Repairs are syntactic only; semantic errors require model-side fixes.
- Supports a practical JSON Schema subset, not the full specification.
FAQ
Why not just use the model's "strict mode"?
Strict mode isn't available on every model or self-hosted endpoint, and you still need to validate untrusted third-party output. This tool works on any raw text.
Is my data uploaded?
No. Everything runs in your browser.