JSON Schema Validator

A precise JSON Schema validator that checks JSON data against a schema, aiding developers in API design, validation, and contract testing.

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2,776+
Total Calculations Run
< 15ms
Browser Execution Speed
100%
Client-Side Privacy
4.9 / 5.0
User Satisfaction

Worked Example & Common Values

Below is a sample worked calculation demonstrating how JSON Schema Validator processes input data instantly inside your browser.

Sample Input Minified string: {"id":1,"status":"active","roles":["admin"]}
Computed Result { "id": 1, "status": "active", "roles": [ "admin" ] }
Execution Mode Client-Side In-Browser JS
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About This Tool

The tool validates a JSON document against a JSON Schema using the nlohmann json-schema-validator approach. It accepts schema and instance inputs and returns a boolean validity result along with a structured list of errors that includes the JSON Pointer path, the failing keyword, descriptive messages, and constraint parameters. Conceptually, validation proceeds by parsing the inputs, resolving any $ref references, and applying keyword rules to each value in the data, with recursive descent through objects and arrays. The core value is accurate conformance reporting, enabling precise fixes. Target users are backend engineers, API developers, and data teams who enforce API contracts and data contracts across development, testing, and CI workflows. Unique value lies in its combination of robust reference resolution, support for common Drafts and schema constructs, and rich, path-aware error reporting suitable for automation. Core features include type checks, required properties, enums, numeric and string constraints, array and object validations, combinators (allOf/anyOf/oneOf), and options for draft version selection and custom formats. Use cases include validating request payloads, validating responses, contract testing, and CI validations. Core capabilities are complemented by clear error paths and structured outputs that integrate with tooling pipelines and dashboards. Use cases span API gateways, data pipelines, and microservice architectures where schema governance reduces runtime faults and expedites debugging.

How to Use

  1. Provide inputs: supply the JSON Schema and the JSON document to validate.
  2. Choose draft version (if required) and any policy options (e.g., remote refs).
  3. Run validation to obtain a boolean result and a list of errors with paths.
  4. Review errors: inspect the JSON Pointer path, keyword, and message to identify violations.
  5. Iterate on the schema or data and re-run validation until valid.
How to use nlohmann json schema validator

Frequently Asked Questions

Find Quick Answers

What schema drafts are supported?
The validator supports common keywords and reference resolution for multiple drafts (e.g., draft-07 and later variants as configured by the library version). If a draft mismatch occurs, the tool reports incompatible keywords and suggests an upgrade path.
Can remote schemas be resolved?
Remote $ref resolution is possible when network access is allowed and policies permit. If blocked, resolution errors appear with details, and caching or local mirroring can be used to improve reliability.
How are errors reported?
Errors include a JSON Pointer path, the failing keyword, an explanatory message, and constraint parameters. Multiple issues can be reported in a single validation run to aid comprehensive debugging.
Is this suitable for CI pipelines?
Yes. The tool provides deterministic results and structured outputs that can be consumed by CI systems, enabling automated quality gates for API contracts and data schemas.

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