JSON Schema Validator

About this tool

Syntax validation tells you whether JSON is well-formed; schema validation tells you whether it means the right thing. A JSON Schema declares the required properties, types, formats, ranges and shapes a document must satisfy, and this tool checks a document against one.

Validation is powered by Ajv, the most widely used JSON Schema engine, running entirely in your browser. It targets Draft 2020-12 and validates Draft-07 schemas in a lenient mode, so real-world schemas compile instead of being rejected for an unfamiliar keyword.

Reading the error list is the skill worth learning. Each entry pairs an `instancePath`, which points into your document, with a `schemaPath`, which points at the rule that rejected it. A `required` error reports the object that is missing a property rather than the property itself, so the instancePath is the parent — that surprises people once and then never again.

Turning "report all errors" off is useful on large documents: Ajv stops at the first failure, which is faster and keeps the list focused while you fix problems one at a time. Leave it on when you want the full picture before editing, for example when checking a payload against a schema you did not write.

How to use this tool

1. 1

   Paste your JSON document into the left editor.

2. 2

   Paste the JSON Schema into the right editor, or load the sample to see the format.

3. 3

   Choose whether to report only the first error or all of them.

4. 4

   Press Validate and work through each error using its instancePath and message.

Key features

• Ajv-powered validation for Draft 2020-12 and Draft-07
• Per-error instancePath, schemaPath, keyword, message and params
• Report the first error only, or every error at once
• Format keywords (email, date, uri, …) via ajv-formats
• Separate, precise syntax errors when either input is not valid JSON

Example

{ "id": 1 }  // schema requires "name"

instancePath: (root)
keyword: required
message: must have required property 'name'

Good to know

Frequently asked questions

Further reading

How to validate JSON — There are two different questions hiding behind "is this JSON valid": does it parse, and does it match the shape it is supposed to have.