A JSON Schema V4 and Hyperschema V4 parser and validator.

Validate some data based on a JSON Schema:

gem install json_schema
validate-schema schema.json data.json


require "json"
require "json_schema"

# parse the schema - raise SchemaError if it's invalid
schema_data = JSON.parse(File.read("schema.json"))
schema = JsonSchema.parse!(schema_data)

# expand $ref nodes - raise SchemaError if unable to resolve

# validate some data - raise ValidationError if it doesn't conform
data = JSON.parse(File.read("data.json"))

# iterate through hyperschema links
schema.links.each do |link|
  puts "#{link.method} #{link.href}"

# abort on first error, instead of listing them all:
schema.validate!(data, fail_fast: true)

Errors have a message (for humans), and type (for machines). ValidationErrors also include a path, a JSON pointer to the location in the supplied document which violated the schema. See errors for more info.

Non-bang methods return a two-element array, with true/false at index 0 to indicate pass/fail, and an array of errors at index 1 (if any).

Passing fail_fast: true (default: false) will cause the validator to abort on the first error it encounters and report just that. Even on fully valid data this can offer some speed improvement, since it doesn't have to collect error messages that might be later discarded (think of e.g. the anyOf directive).


Run the test suite with:


Or run specific suites or tests with:

ruby -Ilib -Itest test/json_schema/validator_test.rb
ruby -Ilib -Itest test/json_schema/validator_test.rb -n /anyOf/


  1. Update the version in json_schema.gemspec as appropriate for semantic versioning and add details to CHANGELOG.
  2. git commit those changes with a message like "Bump version to x.y.z".
  3. Run the release task:

    bundle exec rake release