What this tool does
Validate JSON against a JSON Schema in your browser. Find missing fields, type errors, and schema validation issues quickly.
- Validate an API response before handing it to a frontend team.
- Find a missing required field in a webhook payload.
- Generate a starter schema from sample JSON and refine it manually.
JSON Schema Validator
| Path | Issue | Expected | Actual |
|---|---|---|---|
| No validation errors to show. | |||
When this tool is a good fit
JSON Schema Validator helps when you need validation pass or failure details that identify rule violations from JSON data plus a JSON Schema. It is most useful for checking API payloads, config objects, fixtures, and generated JSON against expected rules. The notes below focus on the settings that matter, the checks worth doing before you export, and the limits that tend to cause mistakes.
- Takes JSON data plus a JSON Schema.
- Lets you adjust required fields, type rules, enum values, nested schemas, and draft compatibility.
- Calls out what to review: missing required properties, wrong primitive types, extra fields, and array item rules.
- Produces validation pass or failure details that identify rule violations.
- Fits common jobs such as checking API payloads, config objects, fixtures, and generated JSON against expected rules.
Example jobs
- Validate an API response before handing it to a frontend team.
- Find a missing required field in a webhook payload.
- Generate a starter schema from sample JSON and refine it manually.
How to use JSON Schema Validator
- Prepare JSON data plus a JSON Schema.
- Set required fields, type rules, enum values, nested schemas, and draft compatibility before running the tool.
- Generate or process the result, then review missing required properties, wrong primitive types, extra fields, and array item rules.
- Copy, export, or download validation pass or failure details that identify rule violations.
- Run a second pass if the destination system, document, or workflow has stricter requirements.
What to know before you use it
- JSON data and schema are parsed locally.
- The validator supports common JSON Schema rules such as type, required, properties, items, enum, const, length, numeric bounds, and pattern.
- Remote $ref values are not fetched.
- JSON Schema draft support can differ across validators, especially for newer conditional and composition keywords.
- A schema should model the contract that matters, not every incidental field from one sample.
Checks and edge cases
- Start with required fields and key types, then add stricter rules after the basic contract is stable.
- Keep example valid and invalid payloads beside the schema for future review.
How your data is handled
This tool works in your browser. Toolumina does not upload or keep the content you enter here.
FAQ
Which JSON Schema draft is supported?
This tool supports the Draft 7 features most teams use for day-to-day validation work.
Does it fetch remote $ref schemas?
No. Remote references are intentionally not fetched for privacy and security.
Can it generate a schema?
Yes. The Generate basic schema action creates a starter schema from the current JSON value.