diff --git a/.gitignore b/.gitignore
index 927f10c..fd1065e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@
 /to-json/target/
 /cmake-build-debug/
 /cmake-build-release/
+/src/to-json/target/
diff --git a/src/demo.c b/src/demo.c
new file mode 100644
index 0000000..4cc3f16
--- /dev/null
+++ b/src/demo.c
@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include "to_json.h"
+
+int main() {
+    printf("start demo\n");
+
+    char raw_string[] = "hello";
+
+    const char *json_content = to_json_rust(raw_string);
+
+    printf("return content -> `%s`\n", json_content);
+
+    free_rust_string(json_content);
+
+    printf("rust string free success\n");
+
+    return 0;
+}
diff --git a/src/to-json/Cargo.lock b/src/to-json/Cargo.lock
new file mode 100644
index 0000000..3efbc0d
--- /dev/null
+++ b/src/to-json/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "to-json"
+version = "0.1.0"
diff --git a/src/to-json/Cargo.toml b/src/to-json/Cargo.toml
new file mode 100644
index 0000000..a8c79b7
--- /dev/null
+++ b/src/to-json/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "to-json"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib"]
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/src/to-json/src/lib.rs b/src/to-json/src/lib.rs
new file mode 100644
index 0000000..1ece23a
--- /dev/null
+++ b/src/to-json/src/lib.rs
@@ -0,0 +1,15 @@
+use std::ffi::{c_char, CStr, CString};
+
+#[no_mangle]
+pub unsafe extern "C" fn to_json_rust(content: *const c_char) -> *const c_char {
+    let content: &str = CStr::from_ptr(content).to_str().unwrap();
+
+    println!("Raw content -> {}", content);
+
+    CString::new(content).unwrap().into_raw()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn free_rust_string(string: *const c_char) {
+    let _ = CString::from_raw(string as *mut _);
+}
diff --git a/src/to-json/to_json.h b/src/to-json/to_json.h
new file mode 100644
index 0000000..5dff661
--- /dev/null
+++ b/src/to-json/to_json.h
@@ -0,0 +1,8 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+const char *to_json_rust(const char *content);
+
+void free_rust_string(const char *string);