Free JSON to C Converter Online
Convert JSON to C structs instantly in your browser.
JSON Input
C Output
What Is JSON to C?
Integrating a REST API or reading a config file in C means you need struct definitions that match your JSON shape — and writing them by hand for a deeply nested payload is a real time sink. This tool reads your JSON (as defined by ECMA-404) and outputs typedef struct definitions you can drop straight into a C project. It follows the key/value mapping that libraries like cJSON and json-c expect, and stays true to the RFC 8259 JSON standard. The struct generation is done in this tab, so production payloads never leave your machine. If you've ever had to hand-write C structs from a REST API response or a config file, you know how tedious it gets — especially when the JSON has 20+ fields. C has no native JSON types, so libraries like json-c or cJSON parse JSON at runtime into trees. This tool skips the manual work — paste your JSON, get typedef struct definitions instantly. The JSON specification on json.org defines the format. See also RFC 8259 for the official JSON standard.
Conversion runs in your browser. Set the struct name in the config panel. Nothing is sent to a server. The generated structs work with C projects. For C++, use JSON to C++ for classes and std::vector.
How to Use This Tool
Paste or Upload JSON
Paste a JSON payload or load one with Upload, then type the name you want for the top-level struct in the config panel. Malformed input produces an error message rather than half-built structs, so run it through the JSON Validator to check syntax first.
Copy or Download
Use Copy or Download. For formatting JSON first, use the JSON Formatter. For validation, use the JSON Validator.
JSON to C Examples
Here is an example of generating C structs from a JSON object.
Example: Subscriber record
JSON input:
Generated C output:
When JSON to C Helps
When writing embedded systems, firmware, or legacy C code that consumes REST APIs or config files, you need struct definitions for the JSON. Pasting a sample here gives you C structs you can use with cJSON or json-c. Manually writing structs for complex nested JSON is error-prone; this tool infers the structure from your sample. For pulling out specific values first, use jq.
Frequently Asked Questions
How do I convert JSON to a C struct?
Paste your JSON above and the tool generates typedef struct definitions immediately. Use cJSON or json-c to parse JSON at runtime and populate these structs.
Which JSON library should I use for C?
cJSON is a single-header library ideal for embedded. json-c suits Unix/Linux projects.
Is my JSON data private?
Yes. The C structs are generated by script on this page and the JSON is never sent to a backend, which matters when the sample payload holds API tokens or customer records.
Can I use the generated structs in embedded systems?
Absolutely. The generated structs are plain C89/C99 compatible. cJSON was specifically designed for constrained embedded environments.
How are nested JSON objects handled?
Nested objects become nested typedef struct declarations. Arrays become pointer types. You control memory allocation (stack, heap, or static).