diff --git a/fs/fs.wasm-gc.mbt b/fs/fs.wasm-gc.mbt
new file mode 100644
index 0000000..d1c62e9
--- /dev/null
+++ b/fs/fs.wasm-gc.mbt
@@ -0,0 +1,75 @@
+/// Reads the contents of a file into a string.
+///
+/// # Parameters
+/// - `path`: An `ExternString` representing the file path.
+///
+/// # Returns
+/// An `ExternString` containing the file contents.
+///
+/// # Note
+/// This is an unstable function call and should be used internally only.
+fn read_file_to_string(path : @ffi.ExternString) -> @ffi.ExternString = "__moonbit_fs_unstable" "read_file_to_string"
+
+/// Writes a string to a file.
+///
+/// # Parameters
+/// - `path`: An `ExternString` representing the file path.
+/// - `content`: An `ExternString` containing the content to be written to the file.
+///
+/// # Note
+/// This is an unstable function call and should be used internally only.
+fn write_string_to_file(path : @ffi.ExternString, content : @ffi.ExternString) = "__moonbit_fs_unstable" "write_string_to_file"
+
+/// Checks if a path exists.
+///
+/// # Parameters
+/// - `path`: An `ExternString` representing the file path.
+///
+/// # Returns
+/// A boolean indicating whether the path exists.
+///
+/// # Note
+/// This is an unstable function call and should be used internally only.
+fn path_exists(path : @ffi.ExternString) -> Bool = "__moonbit_fs_unstable" "path_exists"
+
+fn read_to_string(path : String) -> String {
+  let content = read_file_to_string(@ffi.string_to_extern(path))
+  @ffi.string_from_extern(content)
+}
+
+/// Writes a string to a file.
+///
+/// # Parameters
+/// - `path`: A `String` representing the file path.
+/// - `content`: A `String` containing the content to be written to the file.
+pub fn write_to_string(path : String, content : String) -> Unit {
+  write_string_to_file(
+    @ffi.string_to_extern(path),
+    @ffi.string_to_extern(content),
+  )
+}
+
+/// Checks if a path exists.
+///
+/// # Parameters
+/// - `path`: A `String` representing the file path.
+///
+/// # Returns
+/// A boolean indicating whether the path exists.
+pub fn exists(path : String) -> Bool {
+  path_exists(@ffi.string_to_extern(path))
+}
+
+/// Reads the entire contents of a file into a string.
+///
+/// # Parameters
+/// - `path`: A `String` representing the file path.
+///
+/// # Returns
+/// A `String` containing the file contents if the file exists, otherwise raises an error.
+pub fn read_all(path : String) -> String! {
+  if not(exists(path)) {
+    fail!("File does not exist")
+  }
+  read_to_string(path)
+}
diff --git a/fs/internal/ffi/array.wasm-gc.mbt b/fs/internal/ffi/array.wasm-gc.mbt
new file mode 100644
index 0000000..0c6b18f
--- /dev/null
+++ b/fs/internal/ffi/array.wasm-gc.mbt
@@ -0,0 +1,9 @@
+pub type JSArray
+
+pub fn array_len(arr : JSArray) -> Int = "__moonbit_fs_unstable" "array_len"
+
+pub fn array_get(arr : JSArray, idx : Int) -> JSValue = "__moonbit_fs_unstable" "array_get"
+
+pub fn JSArray::op_get(self : JSArray, idx : Int) -> JSValue {
+  return array_get(self, idx)
+}
diff --git a/fs/internal/ffi/jsvalue.wasm-gc.mbt b/fs/internal/ffi/jsvalue.wasm-gc.mbt
new file mode 100644
index 0000000..3545a88
--- /dev/null
+++ b/fs/internal/ffi/jsvalue.wasm-gc.mbt
@@ -0,0 +1,5 @@
+type JSValue
+
+pub fn jsvalue_is_string(v : JSValue) -> Bool = "__moonbit_fs_unstable" "jsvalue_is_string"
+
+pub fn jsvalue_get_string(v : JSValue) -> ExternString = "%identity"
diff --git a/fs/internal/ffi/moon.pkg.json b/fs/internal/ffi/moon.pkg.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/fs/internal/ffi/moon.pkg.json
@@ -0,0 +1 @@
+{}
diff --git a/fs/internal/ffi/string.wasm-gc.mbt b/fs/internal/ffi/string.wasm-gc.mbt
new file mode 100644
index 0000000..fb97827
--- /dev/null
+++ b/fs/internal/ffi/string.wasm-gc.mbt
@@ -0,0 +1,40 @@
+type StringCreateHandle
+
+type StringReadHandle
+
+pub type ExternString
+
+fn begin_create_string() -> StringCreateHandle = "__moonbit_fs_unstable" "begin_create_string"
+
+fn string_append_char(handle : StringCreateHandle, ch : Char) = "__moonbit_fs_unstable" "string_append_char"
+
+fn finish_create_string(handle : StringCreateHandle) -> ExternString = "__moonbit_fs_unstable" "finish_create_string"
+
+pub fn string_to_extern(s : String) -> ExternString {
+  let handle = begin_create_string()
+  s.iter().each(fn(ch) { string_append_char(handle, ch) })
+  finish_create_string(handle)
+}
+
+fn begin_read_string(s : ExternString) -> StringReadHandle = "__moonbit_fs_unstable" "begin_read_string"
+
+/// Read one char from the string, returns -1 if the end of the string is reached.
+/// The number returned is the unicode codepoint of the character.
+fn string_read_char(handle : StringReadHandle) -> Int = "__moonbit_fs_unstable" "string_read_char"
+
+fn finish_read_string(handle : StringReadHandle) = "__moonbit_fs_unstable" "finish_read_string"
+
+pub fn string_from_extern(e : ExternString) -> String {
+  let buf = Buffer::new()
+  let handle = begin_read_string(e)
+  while true {
+    let ch = string_read_char(handle)
+    if ch == -1 {
+      break
+    } else {
+      buf.write_char(Char::from_int(ch))
+    }
+  }
+  finish_read_string(handle)
+  buf.to_string()
+}
diff --git a/fs/internal/moon.pkg.json b/fs/internal/moon.pkg.json
new file mode 100644
index 0000000..9e26dfe
--- /dev/null
+++ b/fs/internal/moon.pkg.json
@@ -0,0 +1 @@
+{}
\ No newline at end of file
diff --git a/fs/moon.pkg.json b/fs/moon.pkg.json
new file mode 100644
index 0000000..01514af
--- /dev/null
+++ b/fs/moon.pkg.json
@@ -0,0 +1,5 @@
+{
+    "import": [
+        "moonbitlang/x/fs/internal/ffi"
+    ]
+}