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JSON to C: Deserialize JSON to C Structs - Complete Guide

Learn how to deserialize JSON data to C structs with parsing, serialization, and deserialization code generation.

Step 1

Input Your JSON Data

Start by adding your JSON data that needs to be converted to C structs. The tool analyzes the structure to generate appropriate struct definitions following the ISO C standards.

Example: Try This JSON Data

Copy and paste this JSON example to see how it works:

{
  "server": {
    "id": 42,
    "name": "web-server-01",
    "hostname": "api.example.com",
    "port": 8080,
    "isActive": true,
    "tags": [
      "production",
      "api",
      "critical"
    ],
    "config": {
      "maxConnections": 1000,
      "timeout": 30,
      "enableLogging": true
    }
  }
}
Step 2

Review Generated C Structs

Watch as your JSON transforms into clean C struct definitions with proper type mappings following ISO C standards and memory management best practices from Linux Kernel coding style.

Struct definitions: Clean C struct definitions with typedef for easy usage
Type mapping: Automatic C type mapping following C type system (int, double, char*, bool, arrays)
Nested structures: Handle complex JSON hierarchies with nested structs
Array handling: Proper array support with dynamic memory allocation
Step 3

Get Parsing Functions

Your conversion includes complete parsing functions using cJSON library for JSON processing in C.

C Code Output

Your JSON becomes these C structs and functions:

/* Struct definitions */
typedef struct {
    int max_connections;
    int timeout;
    bool enable_logging;
} Config;

typedef struct {
    int id;
    char* name;
    char* hostname;
    int port;
    bool is_active;
    char** tags;
    size_t tags_count;
    Config config;
} Server;

/* Parsing function */
Server* parse_server(const char* json_string);

/* Cleanup function */
void free_server(Server* obj);
Step 4

Copy or Download C Code

Perfect! Now you can use your C structs in your applications for JSON processing with proper memory management.

Copy to clipboard for immediate use in your C projects
Download .c file for integration into your codebase
Embedded systems - Perfect for IoT and microcontroller projects with FreeRTOS and Zephyr RTOS
System programming - API integration and data processing with GNU C Library

What is JSON to C Conversion and Deserialization?

JSON to C conversion (also called JSON deserialization in C) transforms JSON data structures into C structs with proper type definitions, parsing functions, and memory management code. This process analyzes JSON structure and generates production-ready C code that can deserialize JSON, parse, validate, and work with JSON data using popular libraries like cJSON, following ISO/IEC 9899 C standards.

Serialization converts C structs to JSON text, while deserialization converts JSON text back to C structs. Our tool helps you generate the struct definitions and code needed for both operations. The generated C code includes struct definitions, JSON parsing functions using cJSON library, and cleanup functions for proper memory deallocation, making it easy to integrate JSON processing into C applications, embedded systems with FreeRTOS, Zephyr, Mbed OS, and low-level programming projects compatible with GCC and Clang compilers. You can also deserialize JSON online or explore C to JSON serialization.

Frequently Asked Questions

What JSON library is used for parsing in C?

The tool generates parsing code using cJSON, one of the most popular and lightweight JSON libraries for C. cJSON is easy to integrate, has no dependencies, and works great for embedded systems and desktop applications. Make sure to validate your JSON before generating structs.

How does memory management work in the generated C code?

The generated code includes cleanup functions (free_*) that properly deallocate all dynamically allocated memory including strings, arrays, and nested structs. Always call the cleanup function when you're done with the data to prevent memory leaks. The code uses malloc for allocation and free for deallocation following C best practices.

Can I use this for embedded systems and IoT projects?

Absolutely! The generated C code is perfect for embedded systems, microcontrollers, and IoT devices. cJSON is lightweight and has minimal dependencies, making it ideal for resource-constrained environments. The code works with any C99-compatible compiler.

How are JSON arrays handled in C structs?

JSON arrays become pointer fields with a corresponding size_t count field in the struct. For example, a JSON array of strings becomes char** with a size_t count. This allows you to track both the array data and its length, which is essential in C for safe array iteration.

What C data types are used for JSON values?

JSON strings become char*, numbers become int or double, booleans become bool (from stdbool.h), arrays become pointers with count fields, and objects become nested structs. The tool follows standard C conventions for type mapping to ensure compatibility and clarity.

Is the JSON to C converter free to use?

Yes, completely free with no limitations on JSON complexity, struct generation, or usage frequency. No registration required, and you can generate unlimited C structs from JSON data at no cost. Perfect for both hobbyist and professional C development.