A fast Java JSON schema draft v4 validator
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A Java json schema validator that supports json schema draft v4. It is a key component in our light-4j microservices framework to validate request against OpenAPI specification for light-rest-4j and RPC schema for light-hybrid-4j at runtime.

This project is an implementation of the JSON Schema Core Draft v4 specification. It uses the Jackson for json parsing.

Why to use this library?

  • It is the fastest Java Json Schema Validator as far as I know. Here is the testing result compare with other two open source implementations. It is about 32 times faster than fge and 5 times faster than everit.

fge: 7130ms

everit-org: 1168ms

networknt: 223ms

You can run the performance tests for three libraries from https://github.com/networknt/json-schema-validator-perftest

  • It uses Jackson which is the most popular JSON parser in Java.

Maven installation

Add the following to your pom.xml:



To use the validator, you need to have both JsonSchema object and JsonNode object constructed and there are many ways to do that. Here is my base test class that shows you several way to construct these from String, Stream, Url and JsonNode. Pay attention on JsonSchemaFactory class as it is the way to construct JsonSchema object.

 * Copyright (c) 2016 Network New Technologies Inc.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *      http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package com.networknt.schema;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.InputStream;
import java.net.URL;

 * Created by steve on 22/10/16.
public class BaseJsonSchemaValidatorTest {
    protected JsonNode getJsonNodeFromClasspath(String name) throws Exception {
        InputStream is1 = Thread.currentThread().getContextClassLoader()

        ObjectMapper mapper = new ObjectMapper();
        JsonNode node = mapper.readTree(is1);
        return node;

    protected JsonNode getJsonNodeFromStringContent(String content) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        JsonNode node = mapper.readTree(content);
        return node;

    protected JsonNode getJsonNodeFromUrl(String url) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        JsonNode node = mapper.readTree(new URL(url));
        return node;

    protected JsonSchema getJsonSchemaFromClasspath(String name) throws Exception {
        JsonSchemaFactory factory = JsonSchemaFactory.getInstance();
        InputStream is = Thread.currentThread().getContextClassLoader()
        JsonSchema schema = factory.getSchema(is);
        return schema;

    protected JsonSchema getJsonSchemaFromStringContent(String schemaContent) throws Exception {
        JsonSchemaFactory factory = JsonSchemaFactory.getInstance();
        JsonSchema schema = factory.getSchema(schemaContent);
        return schema;

    protected JsonSchema getJsonSchemaFromUrl(String url) throws Exception {
        JsonSchemaFactory factory = JsonSchemaFactory.getInstance();
        JsonSchema schema = factory.getSchema(new URL(url));
        return schema;

    protected JsonSchema getJsonSchemaFromJsonNode(JsonNode jsonNode) throws Exception {
        JsonSchemaFactory factory = JsonSchemaFactory.getInstance();
        JsonSchema schema = factory.getSchema(jsonNode);
        return schema;

And the following is one of the test cases in one of the test classes extends from above base class. As you can see, it constructs JsonSchema and JsonNode from String.

		JsonSchema schema = getJsonSchemaFromStringContent("{\"enum\":[1, 2, 3, 4],\"enumErrorCode\":\"Not in the list\"}");
		JsonNode node = getJsonNodeFromStringContent("7");
		Set<ValidationMessage> errors = schema.validate(node);
		assertThat(errors.size(), is(1));

Known issues

I have just updated the test suites from the official website as the old ones were copied from another Java validator. Now there are several issues that need to be addressed. All of them are edge cases in my opinion but need to be investigated. As my old test suites were inherited from another Java JSON Schema Validator, I guess other Java Validator would have the same issues as these issues are in the Java Language itself.