docs/object-serialization/index.md

---
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Binary Object Serialization reconstructs object graphs, including registered application types,
collections, polymorphic values, and optional shared references.

## Choose a mode

| Mode            | Use it when                                          | Start here                        |
| --------------- | ---------------------------------------------------- | --------------------------------- |
| Xlang (default) | Bytes cross runtime boundaries                       | [Xlang Serialization](xlang.md)   |
| Native          | Every writer and reader uses the same runtime family | [Native serialization](native.md) |

Xlang and native are the only object-serialization modes. Row Format is a random-access analytical
representation, and Fory JSON is a Java JSON codec; use the
[format chooser](../introduction/choose-a-format.md) when object reconstruction is not your goal.

## Read the concepts and modes

Read these pages before choosing a runtime API:

1. [Core Concepts](core-concepts.md) explains object graphs, types, schemas, references,
   polymorphism, and schema evolution across both modes.
2. [Xlang Serialization](xlang.md) explains the portable format used by default and the rules that
   different language runtimes must share.
3. [Native Serialization](native.md) explains when a same-runtime native format is appropriate.

## Browse by runtime

Choose a runtime to find its installation route, lifecycle, exact APIs, configuration, type
registration, schema behavior, extensions, platforms, and troubleshooting:

| Runtime               | Modes                | Documentation                                          |
| --------------------- | -------------------- | ------------------------------------------------------ |
| Java                  | xlang and native     | [Java runtime](./java/index.md)                        |
| Python                | xlang and native     | [Python runtime](./python/index.md)                    |
| C++                   | xlang and native     | [C++ runtime](./cpp/index.md)                          |
| Go                    | xlang and native     | [Go runtime](./go/index.md)                            |
| Rust                  | xlang and native     | [Rust runtime](./rust/index.md)                        |
| JavaScript/TypeScript | xlang                | [JavaScript/TypeScript runtime](./javascript/index.md) |
| C#                    | xlang                | [C# runtime](./csharp/index.md)                        |
| Swift                 | xlang                | [Swift runtime](./swift/index.md)                      |
| Dart                  | xlang                | [Dart runtime](./dart/index.md)                        |
| Scala                 | xlang and JVM native | [Scala runtime](./scala/index.md)                      |
| Kotlin                | xlang and JVM native | [Kotlin runtime](./kotlin/index.md)                    |

## Specifications

- [Xlang serialization format](../specification/xlang_serialization_spec.md)
- [Java native object graph format](../specification/java_serialization_spec.md)
- [Xlang type mapping](../specification/xlang_type_mapping.md)