JSON Schema Validator / Generator
Options
type, required, properties, itemsenum, minLength, minimumadditionalProperties: falsetype: ["string", "null"]What is a JSON Schema Validator / Generator?
A JSON Schema Validator / Generator helps you create JSON Schema from sample JSON and validate JSON data against an existing schema.
This is useful for API contracts, backend validation, testing structured responses, and documenting expected payload formats.
How to use the JSON Schema Validator / Generator
- Paste JSON into the input field.
- Click Generate schema to create a JSON Schema.
- Edit or replace the schema if needed.
- Click Validate JSON to validate the input against the schema.
Tips
- Generated schemas are useful as a starting point, but you may want to refine them manually.
- Validation errors help identify which field or path does not match the schema.
- Required fields can be toggled when generating object schemas.
- This tool is useful for APIs, tests, automation, and AI JSON output validation.
- You can manually add enum, minLength, minimum, nullable types, and additionalProperties false.
Schema design checks
Required versus optional
Mark fields as required only when every valid payload must include them. Optional fields are better for phased API rollouts and partial responses.
Strict additional properties
Use additionalProperties false when unexpected fields should fail validation, but avoid it when clients may send forward-compatible metadata.
Nullable values
Represent nullable fields explicitly with type arrays such as ["string", "null"] so null is not confused with a missing field.
Enums and ranges
Add enum, minimum, minLength, and similar constraints after generation to make the schema closer to the real business contract.
Example JSON Schema
You can also edit the generated schema manually. This version supports common rules such as type, required, enum, minLength, minimum, nullable types, array items, and additionalProperties.
{
"type": "object",
"required": ["name"],
"properties": {
"name": {
"type": "string",
"minLength": 2
},
"age": {
"type": "integer",
"minimum": 18
},
"status": {
"type": "string",
"enum": ["active", "disabled"]
},
"nickname": {
"type": ["string", "null"]
}
},
"additionalProperties": false
}Related guides
Learn the workflow behind this tool and what to check next.
How to debug API JSON responses
Format the response, confirm the HTTP status, validate the schema, and compare payload changes before changing application code.
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Schema validation checks for real API payloads
Use schema validation to make payload assumptions explicit before they become frontend bugs, backend edge cases, or integration failures.
Required fields
Confirm which fields must exist, which can be omitted, and which can be null without breaking consumers.
Type boundaries
Check arrays, objects, numbers, enums, dates, and string formats against the exact shape your application expects.
Contract drift
Compare sample responses against the schema after API changes, vendor upgrades, or webhook version changes.
Readable errors
Use validation paths to find the exact property that failed instead of scanning a large payload manually.
Privacy and usage
Built for quick checks without an account
Toolinix tools are designed for short developer tasks: paste a safe sample, inspect the result, copy what you need, and move on.
No login required
You can use the tools without creating an account, subscribing to a newsletter, or saving a workspace.
Local when possible
Formatters, generators, encoders, and text utilities generally run in your browser. Network diagnostics may need a server-assisted lookup to check public URLs, domains, or IPs.
Keep secrets out
Do not paste production passwords, private keys, access tokens, customer records, or regulated data into online tools unless your own security policy allows it.
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