json-schema-validator

A fast, developer-friendly CLI tool for validating JSON files against JSON Schema (Draft 4/6/7/2020-12).

Features

• Multiple Draft Support — JSON Schema Draft 4, 6, 7, and 2020-12
• Colored Output — Clear, color-coded terminal output with error locations
• Batch Validation — Validate multiple files or entire directories at once
• Watch Mode — Re-validate on file changes
• Exit Codes — CI/CD friendly exit codes (0 = valid, 1 = invalid, 2 = error)
• Detailed Error Paths — Precise JSON Pointer paths to invalid locations
• Schema Discovery — Auto-detect $schema references in JSON files
• Zero Config — Works out of the box with sensible defaults

Installation

npm install -g json-schema-validator-cli

Or run directly with npx:

npx json-schema-validator-cli validate schema.json data.json

Usage

Basic Validation

# Validate a single file
jsonschema validate schema.json data.json

# Validate multiple files
jsonschema validate schema.json file1.json file2.json file3.json

# Validate all JSON files in a directory
jsonschema validate schema.json ./data/

Options

jsonschema validate <schema> <files...> [options]

Options:
  --draft <version>    Force schema draft (4, 6, 7, 2020-12)
  --strict             Enable strict mode (no additional properties)
  --verbose            Show all errors (default: first 10)
  --json               Output errors as JSON
  --quiet              Only show exit code, no output
  --watch              Re-validate on file changes
  --ignore <pattern>   Glob pattern to ignore files

Schema Info

# Inspect a schema file
jsonschema info schema.json

Generate Sample

# Generate a sample JSON from a schema
jsonschema sample schema.json

Examples

Valid file

$ jsonschema validate user-schema.json user.json

  ✔ user.json is valid

Invalid file

$ jsonschema validate user-schema.json user.json

  ✗ user.json is invalid

    errors (3):
    1. /age — must be >= 0, got -5
    2. /email — must match format "email", got "not-an-email"
    3. /address/zipCode — must be string, got 12345

Exit Codes

Code	Meaning
0	All files valid
1	One or more files failed validation
2	Tool error (bad schema, missing files, etc.)

Programmatic API

const { validate, validateFile } = require('json-schema-validator-cli');

// Validate data against schema
const result = validate(schemaObject, dataObject);
// { valid: true, errors: [] }

// Validate a file on disk
const fileResult = await validateFile('schema.json', 'data.json');
// { valid: false, errors: [{ path: '/name', message: '...' }] }

Schema Formats Supported

• Draft 4 — Most widely supported, used by many OpenAPI specs
• Draft 6 — Adds const, contains, propertyNames
• Draft 7 — Adds if/then/else, $comment
• 2020-12 — Latest draft with $dynamicRef

CI/CD Integration

# GitHub Actions example
- name: Validate JSON configs
  run: npx json-schema-validator-cli validate config-schema.json ./configs/ --quiet

License

MIT