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title: Overview sidebar_position: 1 id: index license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You 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, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Fory JSON is Apache Fory's thread-safe Java JSON codec. It provides interpreted and runtime-generated codecs for Java objects, records, immutable creator-based classes, common JDK types, generic containers, custom complete-value codecs, and finite annotation-declared polymorphism.

Fory JSON is a separate data format from Fory‘s binary native and xlang protocols. Use it when a system must exchange ordinary JSON with browsers, APIs, logs, configuration, or another JSON implementation. Use the Fory binary protocol when you need cross-language schema metadata, reference identity, circular graphs, or Fory’s binary-only features.

Documentation map

Goal	Page
First runnable JSON round trip	Getting Started
Understand Java object mapping and configuration	Object Mapping
Configure properties, creators, values, validators, and subtypes	Annotations
Extend complete values, children, and map keys	Custom Codecs
Deploy on Android	Android
Build a GraalVM native image	GraalVM Native Image
Decode input safely	Security
Diagnose failures	Troubleshooting

Limits and unsupported features

Fory JSON intentionally has a smaller semantic surface than the Fory binary protocol and general Jackson object mapping:

• no shared-reference identity or circular-reference protocol;
• no open polymorphism, JSON class-name IDs, runtime subtype discovery, or runtime subtype table extension;
• no InputStream parser or incremental OutputStream writer on the ForyJson root API;
• no pretty-print configuration;
• no Jackson/Gson annotation compatibility layer;
• no aliases, views, filters, injection, managed/back references, object identity annotations, or root wrapping;
• no Fory core Expose processing.

Circular graphs eventually fail maxDepth; they are not reconstructed. Use Fory core's binary native or xlang protocol when reference identity or cycles are required.

Related Java guides

For binary serialization, start with Java Object Serialization and choose xlang or native. Binary builder options are documented separately in Java Configuration.