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JSON Schema Generator & Validator

Structured outputs from LLMs, API contracts and config files all need a schema. Paste a sample document to get a draft-07 or 2020-12 schema you can refine, or paste a schema and documents to validate them, with each failure reported at its JSON path with the rule that failed.

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How it works

01

Generate

Paste one or several sample documents; the generator infers types, required keys, enums for small value sets and formats for dates and emails.

02

Refine

Edit the schema in place; the validator re-runs on the samples as you type.

03

Validate

Paste a document or a JSONL file of documents; errors list path, rule and the offending value.

Formats, limits and the numbers that matter

Drafts

Draft-07 is what most tools accept; 2020-12 adds prefixItems and unevaluated keywords. Both are supported by the validator.

LLM structured output

OpenAI strict mode requires additionalProperties false and every property required; the strict toggle applies both.

Inference limits

Samples cannot reveal optional keys that never appear; review required lists by hand.

Common questions

Can it validate YAML?

Convert to JSON in the YAML tool first, or paste YAML here and it is converted automatically.

Does it support $ref?

Local references within the document, yes; remote references are not fetched.

Pydantic or TypeScript output?

Planned; for now the schema is the exchange format.

Next in the workflow

JSON Formatter, Validator & Tree ViewerFormat, validate, minify and explore JSON as a collapsible tree, with a path query and error positions.YAML, JSON & TOML ConverterConvert between YAML, JSON and TOML with validation, and see exactly where a config file breaks.JSONL Viewer & ValidatorOpen large JSONL files, see the schema and statistics, find bad lines and duplicates, filter and convert to CSV.