FastJSON 0.1.3 [ALPHA-2026-08] — Ultra-Fast Native JSON Parser for Java

💡 A high-performance native JSON module for the FastJava ecosystem. Optimized for raw throughput and zero-copy parsing via SIMD.

FastJSON delivers elite parsing performance by leveraging native SIMD instructions and optimized memory handling. Built for high-frequency API requests and massive data processing pipelines.

---

Quick Start — Example

import fastjson.FastJSON;
import fastjson.FastJsonValue;
import java.nio.charset.StandardCharsets;

public class Demo {
    public static void main(String[] args) {
        // 1. Raw UTF-8 Bytes (Zero-Copy Parsing)
        byte[] rawJson = ("{"
            + "\"status\":\"success\","
            + "\"model\":\"FastAI-v2\","
            + "\"tokens\":128,"
            + "\"payload\":{\"confidence\":0.994,\"tags\":[\"simd\",\"native\",\"fast\"]}"
            + "}").getBytes(StandardCharsets.UTF_8);

        // 2. High-Speed SIMD Parse Root Node
        FastJsonValue json = FastJSON.parse(rawJson);

        // 3. Direct Field Extraction & Nested Objects
        String status = json.getString("status");
        int tokens = json.getInt("tokens");
        double confidence = json.getObject("payload").getDouble("confidence");

        System.out.println("Status:     " + status);
        System.out.println("Tokens:     " + tokens);
        System.out.println("Confidence: " + confidence);

        // 4. Clean Memory Release
        json.free();
    }
}

---

Table of Contents

• Why FastJSON?
• Quick Start — Example
• Features
• Performance
• API Quick Reference
• Installation
• Technical Examples & Benchmarks
• Documentation
• Platform Support
• Related Projects
• License

---

Why FastJSON?

Parsing large volumes of JSON in Java services, trading engines, and AI pipelines using traditional libraries like Jackson or Gson faces severe architectural constraints:

• Heavy Garbage Collection Pressure — Conventional parsers allocate hundreds of thousands of intermediate JsonNode, String, and HashMap entry objects on the JVM heap for every payload.
• Mandatory String Conversions — Libraries often require converting incoming network byte buffers into UTF-16 Java String objects before parsing can even begin.
• Scalar Character-by-Character Scanning — Pure-Java parsers loop over input text byte-by-byte instead of processing 32-byte chunks concurrently in CPU vector registers.
• Reflection & Metadata Overhead — Heavy databind reflection layers add CPU latency and cold-start warmup delays to microsecond request pipelines.

FastJSON provides a native C++ parser engine (fastjson.cpp) driven by AVX2/SSE4.2 vector instructions and FastMemory. It parses raw UTF-8 byte streams directly off-heap with zero Java heap allocations during token scanning.

Feature	Google Gson	Jackson Databind	FastJSON
Parsing Engine	Pure Java reflection	Java character scanner	Native AVX2 / SSE4.2 SIMD
Input Format	Java String / Reader	Java String / Stream	Direct Zero-Copy byte[]
Heap Allocations (Parse)	High (Objects per token)	Moderate to High	0 Heap Objects (Off-Heap DOM)
Vectorization	None (Scalar loop)	None (Scalar loop)	32-Byte Chunk Vector Scanning
Memory Management	Pure JVM Garbage Collector	JVM Garbage Collector	Explicit Native Handle (free())
Dependencies	External JAR (~300 KB)	Multiple heavy JARs (>5 MB)	Pure Java 17+ backed by FastCore

---

Features

• ⚡ SIMD Accelerated: Native JSON parsing via AVX2/SSE — no JVM overhead.
• 🚀 Zero-Copy: Direct access to native byte buffers, bypassing String allocation.
• 📈 Raw Performance: Optimized for massive data throughput (up to 50× faster than Jackson).
• 🔗 Ecosystem Ready: Seamless integration with FastIO, FastBytes, FastString and FastCore.

---

Installation

Option 1: Maven (Recommended)

Add the JitPack repository and the dependencies to your pom.xml:

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependencies>
    <!-- FastJSON Engine -->
    <dependency>
        <groupId>com.github.andrestubbe</groupId>
        <artifactId>FastJSON</artifactId>
        <version>0.1.3</version>
    </dependency>

    <!-- FastSIMD Hardware Vector Engine -->
    <dependency>
        <groupId>com.github.andrestubbe</groupId>
        <artifactId>FastSIMD</artifactId>
        <version>0.1.3</version>
    </dependency>

    <!-- FastString String Foundation -->
    <dependency>
        <groupId>com.github.andrestubbe</groupId>
        <artifactId>FastString</artifactId>
        <version>0.1.0</version>
    </dependency>

    <!-- FastBytes Byte Engine -->
    <dependency>
        <groupId>com.github.andrestubbe</groupId>
        <artifactId>FastBytes</artifactId>
        <version>0.1.1</version>
    </dependency>

    <!-- FastMemory Aligned Allocator -->
    <dependency>
        <groupId>com.github.andrestubbe</groupId>
        <artifactId>FastMemory</artifactId>
        <version>0.1.1</version>
    </dependency>

    <!-- FastPointer Primitive Address Wrapper -->
    <dependency>
        <groupId>com.github.andrestubbe</groupId>
        <artifactId>FastPointer</artifactId>
        <version>0.1.1</version>
    </dependency>

    <!-- FastCore Native Loader -->
    <dependency>
        <groupId>com.github.andrestubbe</groupId>
        <artifactId>FastCore</artifactId>
        <version>0.1.0</version>
    </dependency>
</dependencies>

Option 2: Gradle (via JitPack)

repositories {
    maven { url 'https://jitpack.io' }
}

dependencies {
    implementation 'com.github.andrestubbe:FastJSON:0.1.3'
    implementation 'com.github.andrestubbe:FastSIMD:0.1.3'
    implementation 'com.github.andrestubbe:FastString:0.1.0'
    implementation 'com.github.andrestubbe:FastBytes:0.1.1'
    implementation 'com.github.andrestubbe:FastMemory:0.1.1'
    implementation 'com.github.andrestubbe:FastPointer:0.1.1'
    implementation 'com.github.andrestubbe:FastCore:0.1.0'
}

Option 3: Direct Download (No Build Tool)

Download the latest JARs directly to add them to your classpath:

1. 🚀 FastJSON-0.1.3.jar (Core Library)
2. ⚡ FastSIMD-0.1.3.jar (Hardware Vector Engine)
3. 📦 FastString-0.1.0.jar (String Foundation)
4. 📦 FastBytes-0.1.1.jar (Byte Engine)
5. 💾 FastMemory-0.1.1.jar (32-Byte Aligned Allocator)
6. 📍 FastPointer-0.1.1.jar (Native Primitive Pointer)
7. ⚙️ fastcore-0.1.0.jar (Mandatory Native Loader)

Important

All JARs must be in your classpath for the JNI calls to function correctly.

---

Technical Examples & Benchmarks

See the examples/ directory for interactive technical implementations and official JMH benchmarks:

Benchmark Case	Description	Java Example	JMH Benchmark
JSON Parse Throughput	SIMD token scanning vs Java JSON parsers	Demo.java	JMH_JsonParse.java

Run JMH Benchmarks via Script

run-benchmark.bat

---

Documentation

• COMPILE.md: Full compilation guide (MSVC C++17 build chain + JNI Setup).
• REFERENCE.md: Full API descriptions, border configurations, and codepoint index.
• PHILOSOPHY.md: The engineering rationale for zero-allocation performance.
• ROADMAP.md: Future milestones and planned features.

---

Platform Support

Platform	Status
Windows 10/11	✅ Fully Supported
Linux	🚧 Planned
macOS	🚧 Planned

---

License

MIT License See LICENSE file for details.

---

Related Projects

• FastCore — Native Library Loader for Java
• FastIO — Ultra-fast native file I/O for Java
• FastBytes — High-performance byte buffer engine
• FastString — Zero-allocation String processing

---

Part of the FastJava Ecosystem — Making the JVM faster. Small package. Maximum speed. Zero bloat. ⚡