JSON Schema validate

Client

Paste a JSON Schema and an instance, or infer a draft-07 schema from sample JSON. Validation runs locally with Ajv.

Learn more: JSON Schema in the browser

Validate a JSON document against a schema, pretty-print the schema, or infer a draft-07 sketch from sample data—useful before wiring Ajv or OpenAPI in a project.

Validation

The validator compiles your schema with Ajv (draft-07 and common keywords supported via formats). Errors list JSON Pointer–style paths when something fails.

Infer schema

Inference builds a minimal object/array schema from one example—treat it as a starting point, not a proof of every future payload.

Schema & instance

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Paste a JSON Schema (draft 07 or newer features Ajv supports) in the left panel and a JSON instance on the right, then validate. Use Infer schema to build a draft-07 sketch from the instance—adjust types before production.

Complex schemas may need manual review; this is a browser-side check only.

Common use cases

  • Check an API response against the schema your team publishes before merging client code.
  • Infer a draft schema from one or two sample payloads to bootstrap documentation—then tighten types by hand.
  • Format messy schema text so reviews focus on rules instead of indentation.

Common mistakes to avoid

  • Treating inferred schemas as exhaustive

    Inference only sees the samples you paste. Rare fields and edge cases still need explicit rules.

FAQ

Are JSON or schema documents sent to Toolcore?

No. Validation and inference run locally with Ajv in your browser.

More tools

Related utilities you can open in another tab—mostly client-side.