diff --git a/Cargo.lock b/Cargo.lock
index f488319..81a8689 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -164,7 +164,7 @@ checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
 [[package]]
 name = "libtlg-rs"
-version = "0.2.2"
+version = "0.2.3"
 dependencies = [
  "lazy_static",
  "overf",
diff --git a/libtlg-rs/Cargo.toml b/libtlg-rs/Cargo.toml
index e82ac80..dc39fc0 100644
--- a/libtlg-rs/Cargo.toml
+++ b/libtlg-rs/Cargo.toml
@@ -1,12 +1,13 @@
 [package]
 name = "libtlg-rs"
-version = "0.2.2"
+version = "0.2.3"
 description = "Rust version of libtlg"
 edition = "2024"
 license = "MIT"
 repository = "https://github.com/lifegpc/libtlg-rs"
 
 [features]
+capi = []
 encode = []
 
 [dependencies]
diff --git a/libtlg-rs/cbindgen.toml b/libtlg-rs/cbindgen.toml
new file mode 100644
index 0000000..08094f2
--- /dev/null
+++ b/libtlg-rs/cbindgen.toml
@@ -0,0 +1 @@
+language = "C"
diff --git a/libtlg-rs/src/capi.rs b/libtlg-rs/src/capi.rs
new file mode 100644
index 0000000..aa73407
--- /dev/null
+++ b/libtlg-rs/src/capi.rs
@@ -0,0 +1,327 @@
+//! C API for libtlg-rs
+//!
+//! Use follow command to build the C API library
+//! ```shell
+//! cargo install cargo-c
+//! cargo cbuild --release --features "encode"
+//! ```
+use std::ffi::{c_char, c_void};
+#[cfg(feature = "encode")]
+use std::io::Write;
+use std::io::{Read, Seek, SeekFrom};
+
+/// A readable stream for TLG processing.
+pub struct ReadableStream {
+    /// User data pointer.
+    userdata: *mut c_void,
+    /// Read function pointer.
+    read_fn: extern "C" fn(*mut c_void, *mut u8, usize) -> usize,
+    /// Seek function pointer.
+    seek_fn: extern "C" fn(*mut c_void, i64, i32) -> u64,
+}
+
+#[cfg(feature = "encode")]
+/// A writeable stream for TLG processing.
+pub struct WriteableStream {
+    /// User data pointer.
+    userdata: *mut c_void,
+    /// Write function pointer.
+    write_fn: extern "C" fn(*mut c_void, *const u8, usize) -> usize,
+    /// Flush function pointer.
+    flush_fn: extern "C" fn(*mut c_void) -> i32,
+    /// Seek function pointer.
+    seek_fn: extern "C" fn(*mut c_void, i64, i32) -> u64,
+}
+
+#[repr(C)]
+/// A tag in TLG file.
+pub struct Tag {
+    /// Tag name.
+    pub name: *mut c_char,
+    /// Length of tag name.
+    pub name_length: usize,
+    /// Tag value.
+    pub value: *mut c_char,
+    /// Length of tag value.
+    pub value_length: usize,
+}
+
+#[repr(C)]
+/// Color type of TLG image.
+pub enum TlgColorType {
+    /// Grayscale 8-bit.
+    Grayscale8,
+    /// BGR 24-bit.
+    Bgr24,
+    /// BGRA 32-bit.
+    Bgra32,
+}
+
+#[repr(C)]
+pub struct Tlg {
+    /// TLG version. 5 or 6.
+    pub version: u32,
+    /// Image width.
+    pub width: u32,
+    /// Image height.
+    pub height: u32,
+    /// Color type.
+    pub color_type: TlgColorType,
+    /// Pointer to image data.
+    pub data: *mut u8,
+    /// Number of bytes in data.
+    pub data_length: usize,
+    /// Pointer to tags, null if no tags.
+    pub tags: *mut Tag,
+    /// Number of tags.
+    pub tag_count: usize,
+}
+
+impl Read for ReadableStream {
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        let ret = (self.read_fn)(self.userdata, buf.as_mut_ptr(), buf.len());
+        Ok(ret)
+    }
+}
+
+impl Seek for ReadableStream {
+    fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
+        let (offset, whence) = match pos {
+            SeekFrom::Start(off) => (off as i64, 0),
+            SeekFrom::End(off) => (off, 2),
+            SeekFrom::Current(off) => (off, 1),
+        };
+        let ret = (self.seek_fn)(self.userdata, offset, whence);
+        Ok(ret)
+    }
+}
+
+#[cfg(feature = "encode")]
+impl Write for WriteableStream {
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        let ret = (self.write_fn)(self.userdata, buf.as_ptr(), buf.len());
+        Ok(ret)
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        let ret = (self.flush_fn)(self.userdata);
+        if ret == 0 {
+            Ok(())
+        } else {
+            Err(std::io::Error::new(
+                std::io::ErrorKind::Other,
+                "Flush failed",
+            ))
+        }
+    }
+}
+
+#[cfg(feature = "encode")]
+impl Seek for WriteableStream {
+    fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
+        let (offset, whence) = match pos {
+            SeekFrom::Start(off) => (off as i64, 0),
+            SeekFrom::End(off) => (off, 2),
+            SeekFrom::Current(off) => (off, 1),
+        };
+        let ret = (self.seek_fn)(self.userdata, offset, whence);
+        Ok(ret)
+    }
+}
+
+/// Create a readable stream.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn create_readable_stream(
+    userdata: *mut c_void,
+    read_fn: extern "C" fn(*mut c_void, *mut u8, usize) -> usize,
+    seek_fn: extern "C" fn(*mut c_void, i64, i32) -> u64,
+) -> *mut ReadableStream {
+    let stream = ReadableStream {
+        userdata,
+        read_fn,
+        seek_fn,
+    };
+    Box::into_raw(Box::new(stream))
+}
+
+/// Destroy a readable stream.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn destroy_readable_stream(stream: *mut ReadableStream) {
+    if !stream.is_null() {
+        drop(unsafe { Box::from_raw(stream) });
+    }
+}
+
+/// Create a writeable stream.
+#[cfg(feature = "encode")]
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn create_writeable_stream(
+    userdata: *mut c_void,
+    write_fn: extern "C" fn(*mut c_void, *const u8, usize) -> usize,
+    flush_fn: extern "C" fn(*mut c_void) -> i32,
+    seek_fn: extern "C" fn(*mut c_void, i64, i32) -> u64,
+) -> *mut WriteableStream {
+    let stream = WriteableStream {
+        userdata,
+        write_fn,
+        flush_fn,
+        seek_fn,
+    };
+    Box::into_raw(Box::new(stream))
+}
+
+/// Destroy a writeable stream.
+#[cfg(feature = "encode")]
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn destroy_writeable_stream(stream: *mut WriteableStream) {
+    if !stream.is_null() {
+        drop(unsafe { Box::from_raw(stream) });
+    }
+}
+
+/// Check if it's a valid TLG.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn check_tlg(stream: *mut ReadableStream) -> bool {
+    if stream.is_null() {
+        return false;
+    }
+    let stream = unsafe { &mut *stream };
+    match crate::check_tlg(stream) {
+        Ok(valid) => valid,
+        Err(_) => false,
+    }
+}
+
+/// Check if it's a valid TLG.
+/// 11 bytes are needed.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn is_valid_tlg(data: *const u8, length: usize) -> bool {
+    let data = unsafe { std::slice::from_raw_parts(data, length) };
+    crate::is_valid_tlg(data)
+}
+
+/// Load a TLG from a readable stream.
+/// Returns a pointer to Tlg struct, or null on error.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn load_tlg(stream: *mut ReadableStream) -> *mut Tlg {
+    if stream.is_null() {
+        return std::ptr::null_mut();
+    }
+    let stream = unsafe { &mut *stream };
+    match crate::load_tlg(stream) {
+        Ok(mut tlg) => {
+            let color_type = match tlg.color {
+                crate::TlgColorType::Grayscale8 => TlgColorType::Grayscale8,
+                crate::TlgColorType::Bgr24 => TlgColorType::Bgr24,
+                crate::TlgColorType::Bgra32 => TlgColorType::Bgra32,
+            };
+            tlg.data.shrink_to_fit();
+            let data_ptr = tlg.data.as_mut_ptr();
+            let data_len = tlg.data.len();
+            std::mem::forget(tlg.data);
+            let (tag, tag_count) = if tlg.tags.is_empty() {
+                (std::ptr::null_mut(), 0)
+            } else {
+                let mut tags = Vec::with_capacity(tlg.tags.len());
+                for (mut name, mut value) in tlg.tags.drain() {
+                    let name_ptr = name.as_mut_ptr();
+                    let name_len = name.len();
+                    name.shrink_to_fit();
+                    std::mem::forget(name);
+                    let value_ptr = value.as_mut_ptr();
+                    let value_len = value.len();
+                    value.shrink_to_fit();
+                    std::mem::forget(value);
+                    tags.push(Tag {
+                        name: name_ptr as *mut c_char,
+                        name_length: name_len,
+                        value: value_ptr as *mut c_char,
+                        value_length: value_len,
+                    });
+                }
+                let tag_ptr = tags.as_mut_ptr();
+                let tag_count = tags.len();
+                tags.shrink_to_fit();
+                std::mem::forget(tags);
+                (tag_ptr, tag_count)
+            };
+            let tlg_c = Tlg {
+                version: tlg.version,
+                width: tlg.width,
+                height: tlg.height,
+                color_type,
+                data: data_ptr,
+                data_length: data_len,
+                tags: tag,
+                tag_count,
+            };
+            Box::into_raw(Box::new(tlg_c))
+        }
+        Err(_) => std::ptr::null_mut(),
+    }
+}
+
+/// Destroy a Tlg struct.
+/// Also frees the image data.
+/// WARN: Make sure the Tlg struct is created by `load_tlg`.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn destroy_tlg(tlg: *mut Tlg) {
+    if tlg.is_null() {
+        return;
+    }
+    let tlg = unsafe { Box::from_raw(tlg) };
+    let _data = unsafe { Vec::from_raw_parts(tlg.data, tlg.data_length, tlg.data_length) };
+    if !tlg.tags.is_null() {
+        let tags = unsafe { Vec::from_raw_parts(tlg.tags, tlg.tag_count, tlg.tag_count) };
+        for tag in tags {
+            let _name = unsafe {
+                Vec::from_raw_parts(tag.name as *mut u8, tag.name_length, tag.name_length)
+            };
+            let _value = unsafe {
+                Vec::from_raw_parts(tag.value as *mut u8, tag.value_length, tag.value_length)
+            };
+        }
+    }
+}
+
+/// Encode a TLG image to a writeable stream.
+/// Returns true on success, false on error.
+#[cfg(feature = "encode")]
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn save_tlg(tlg: Tlg, stream: *mut WriteableStream) -> bool {
+    if stream.is_null() || tlg.data.is_null() {
+        return false;
+    }
+    let stream = unsafe { &mut *stream };
+    let color = match tlg.color_type {
+        TlgColorType::Grayscale8 => crate::TlgColorType::Grayscale8,
+        TlgColorType::Bgr24 => crate::TlgColorType::Bgr24,
+        TlgColorType::Bgra32 => crate::TlgColorType::Bgra32,
+    };
+    let data = unsafe { std::slice::from_raw_parts(tlg.data, tlg.data_length) }.to_vec();
+    let mut tags = std::collections::HashMap::new();
+    if !tlg.tags.is_null() && tlg.tag_count > 0 {
+        let tag_slice = unsafe { std::slice::from_raw_parts(tlg.tags, tlg.tag_count) };
+        for tag in tag_slice {
+            let name =
+                unsafe { std::slice::from_raw_parts(tag.name as *const u8, tag.name_length) }
+                    .to_vec();
+            let value =
+                unsafe { std::slice::from_raw_parts(tag.value as *const u8, tag.value_length) }
+                    .to_vec();
+            tags.insert(name, value);
+        }
+    }
+    let tlg_rust = crate::Tlg {
+        version: tlg.version,
+        width: tlg.width,
+        height: tlg.height,
+        color,
+        data,
+        tags,
+    };
+    match crate::save_tlg(&tlg_rust, stream) {
+        Ok(_) => true,
+        Err(_) => false,
+    }
+}
diff --git a/libtlg-rs/src/lib.rs b/libtlg-rs/src/lib.rs
index ca559ee..0ae48c2 100644
--- a/libtlg-rs/src/lib.rs
+++ b/libtlg-rs/src/lib.rs
@@ -1,5 +1,7 @@
 //! A Rust library for processing TLG files.
 #![cfg_attr(docsrs, feature(doc_cfg))]
+#[cfg(feature = "capi")]
+pub mod capi;
 mod load_tlg;
 #[cfg(feature = "encode")]
 mod save_tlg;