JSON to C Class Converter
Convert JSON data to C struct definitions with proper type mappings. Generate typedef structs, handle nested objects, arrays, and apply naming conventions for C code. Perfect for C API development and data structure design.
Conversion Options
Recommended Settings
C Struct Best Practices
- •Use typedef to create type aliases for cleaner code and easier refactoring
- •Include header guards (#ifndef) to prevent multiple inclusion errors
- •Use snake_case naming convention for C structs and fields (industry standard)
- •Add size_t count fields for arrays to track array length in C
- •Use bool type (C99+) for clarity, or int for C89 compatibility
Type Mapping Guidelines
- •JSON strings map to char* (null-terminated C strings)
- •JSON numbers map to int (integers) or double (decimals)
- •JSON booleans map to bool (C99) or int (C89) with 0/1 values
- •JSON arrays become pointers with count fields (e.g., items + items_count)
- •Nested JSON objects create separate struct definitions
Pro Tips
- •Generated structs use snake_case naming by default (most common in C)
- •Arrays automatically get count fields to track length (C doesn't store array sizes)
- •Nested objects create multiple struct definitions in the correct dependency order
- •All processing happens in your browser - your JSON never leaves your device
Most Popular
Most users enable typedef and include guards for production-ready header files
When to Use This Tool
Generate C struct definitions from JSON API responses or request formats. Convert JSON schemas into type-safe C structures for parsing API data, handling responses, or building API clients in C.
Create C struct definitions from JSON configuration files, data models, or schemas. Quickly prototype data structures without manually writing boilerplate struct code, ensuring type consistency across your codebase.
Auto-generate C structs for JSON serialization/deserialization libraries. Use generated structs as the foundation for data binding code, ORMs, or custom serialization logic in C applications.
Convert modern JSON data formats to C structures for integration with legacy C codebases. Bridge the gap between JSON-based systems and older C applications that require native struct definitions.
How It Works
Paste your JSON data into the input field on the left
Configure options: typedef, include guards, bool type, and field sorting
Click 'Convert to C Struct' to generate the C struct definition
The tool maps JSON types to C types: string→char*, number→int/double, boolean→bool/int
Arrays automatically get pointer types and count fields (e.g., tags + tags_count)
Nested objects create separate struct definitions in dependency order
Copy the C code to clipboard or download as a .h header file
All processing happens in your browser - your JSON data never leaves your device
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Files never leave your device. All processing happens locally in your browser.
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Frequently Asked Questions
What's the difference between typedef and regular struct?
typedef creates a type alias, allowing you to use 'person_t' instead of 'struct person'. With typedef, you write 'person_t user;' instead of 'struct person user;'. It's cleaner, more concise, and the standard practice in modern C code.
How are JSON arrays handled in C?
JSON arrays become pointer types with accompanying count fields. For example, a 'tags' array becomes 'char** tags' plus 'size_t tags_count'. This is necessary because C arrays don't store their own length, so you need a separate field to track the number of elements.
Can nested JSON objects be converted?
Yes! Nested objects become separate struct definitions. The tool generates all necessary structs in the correct dependency order. For example, a JSON object with a nested 'address' object will create both a main struct and an address_t struct.
What C standard is the generated code compatible with?
By default, the code uses C99 features (bool type, size_t). If you need C89 compatibility, disable 'Use bool type' to use int for booleans instead. The generated structs are compatible with C89, C99, C11, and later standards.
How should I handle null values in C?
JSON null values map to pointer types (void*) in the generated struct. In your C code, you can check for NULL pointers to detect null values. For optional fields, use pointer types and check for NULL before dereferencing.
What's the best naming convention for C structs?
snake_case is the industry standard for C code and is used by default. It's the most common convention in C libraries, kernel code, and established C projects. PascalCase and camelCase are less common but used in some codebases.
Why do I need include guards?
Include guards (#ifndef/#define/#endif) prevent multiple inclusion errors when a header file is included more than once. Without guards, you'll get 'redefinition' errors during compilation. They're essential for header files in any non-trivial C project.
Can I use the generated structs with JSON parsing libraries?
Yes! The generated structs work with JSON parsing libraries like cJSON, jansson, or json-c. Use the struct definitions as the target structure for your JSON deserialization code. You'll need to write parsing logic to map JSON data to struct fields.