JSON to C Converter
Analyses your JSON object or array and produces the corresponding C typedef struct definitions, automatically mapping numbers to int, double, or long long and strings to char*. Options let you toggle standard C headers, typedef usage, a sample main function, and choose between 4-space or tab indentation. Paste any JSON and download a ready-to-compile .c file without leaving your browser.
JSON
Code Style
Struct Name
C Code
What is JSON to C Converter?
Embedded systems, game engines, and performance-critical C applications cannot afford dynamic memory allocation for JSON parsing at runtime — they need fixed struct definitions that map JSON fields to memory layout. This tool generates C typedef struct definitions from a JSON object sample, mapping JSON types to appropriate C types: integers to int or int64_t, floats to double, booleans to int, and strings to char* or fixed-length char arrays for embedded targets. Nested objects produce separate typedef struct definitions; arrays produce pointer-and-count field pairs. The output is compatible with cJSON, jansson, and jsmn for runtime parsing, and can be adapted for no-dynamic-allocation embedded environments by replacing heap pointer types with fixed-size arrays.
How to Use
- 1
Paste Your JSON
Paste a JSON object into the editor. C structs are for fixed schemas — the generator analyses the JSON structure and produces a typedef struct definition with C-compatible field types.
- 2
Configure C Struct Options
Set the root struct name, choose whether to use typedef struct or plain struct, and select how string fields are typed — char* for heap-allocated strings or fixed char[N] arrays for embedded systems.
- 3
Generate C Struct Definitions
Click "Generate C". JSON types are mapped to C types (int, double, int, char*), nested objects produce separate struct typedefs, and arrays produce pointer fields with accompanying size fields.
- 4
Integrate into Your C Project
Copy the struct definitions into your .h header file. Add #include <stdbool.h> for boolean fields and #include <stdint.h> for fixed-width integer types. Use a JSON-C library like cJSON or jansson to populate the structs from JSON strings.
Common Use Cases
Embedded Systems Configuration
Convert JSON configuration payloads from IoT management platforms into C structs for embedded firmware, enabling structured config storage in constrained microcontroller environments.
Game Engine Data Structures
Generate C structs from JSON asset manifests, level data, or entity definitions used in game engines or simulation software written in C for performance-critical applications.
Network Protocol Implementation
Map JSON API response schemas to C structs for implementing JSON-over-HTTP clients in C applications, using cJSON or jansson libraries for parsing into the generated struct types.
Legacy C Codebase Integration
When integrating modern JSON APIs with existing C codebases, generate struct definitions from sample JSON payloads to maintain type safety and avoid raw string parsing throughout the codebase.
Conversion Examples
JSON Object → C Struct Definition
A JSON object generates a C struct with appropriately typed fields.
Input JSON
{
"id": 1,
"name": "sensor_A",
"temperature": 23.5,
"active": true
}Output CSV
typedef struct {
int id;
char* name;
double temperature;
int active; /* bool as int */
} Root;Nested JSON → Nested C Structs
Nested objects generate separate struct definitions with pointer references.
Input JSON
{
"device": {"id": 1, "model": "SensorX"},
"reading": {"value": 23.5, "unit": "celsius"}
}Output CSV
typedef struct {
int id;
char* model;
} Device;
typedef struct {
double value;
char* unit;
} Reading;
typedef struct {
Device device;
Reading reading;
} Root;