diff --git a/Cargo.toml b/Cargo.toml
index c7aba82..9701a3c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,3 +5,6 @@ edition = "2021"
 
 [dependencies]
 clap = "4.4"
+
+[workspace]
+members = ["http"]
diff --git a/http/Cargo.toml b/http/Cargo.toml
new file mode 100644
index 0000000..ed7dbbf
--- /dev/null
+++ b/http/Cargo.toml
@@ -0,0 +1,21 @@
+[package]
+name = "http"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+http = "1.1.0"
+thiserror = "1.0.57"
+url = "2.5.0"
+
+[target.'cfg(unix)'.dependencies]
+curl = "0.4.46"
+
+[target.'cfg(windows)'.dependencies.windows-sys]
+version = "0.52.0"
+features = [
+    "Win32",
+    "Win32_Foundation",
+    "Win32_Networking",
+    "Win32_Networking_WinHttp"
+]
diff --git a/http/src/lib.rs b/http/src/lib.rs
new file mode 100644
index 0000000..0e5a228
--- /dev/null
+++ b/http/src/lib.rs
@@ -0,0 +1,104 @@
+pub use self::request::*;
+pub use self::response::*;
+use http::Method;
+use thiserror::Error;
+use url::Url;
+
+mod request;
+mod response;
+#[cfg(windows)]
+mod winhttp;
+
+/// Struct to construct [`Request`] objects.
+pub struct HttpClient {
+    #[cfg(windows)]
+    session: winhttp::Handle,
+}
+
+impl HttpClient {
+    pub fn new() -> Result<Self, NewError> {
+        Ok(Self {
+            #[cfg(windows)]
+            session: winhttp_open(None).map_err(NewError::CreateWinHttpSessionFailed)?,
+        })
+    }
+
+    pub fn request(&self, method: Method, url: impl AsRef<Url>) -> Result<Request, RequestError> {
+        let url = url.as_ref();
+
+        if !matches!(url.scheme(), "http" | "https") {
+            return Err(RequestError::NotHttp);
+        }
+
+        Request::new(
+            method,
+            url,
+            #[cfg(windows)]
+            &self.session,
+        )
+    }
+
+    #[cfg(windows)]
+    fn winhttp_open(agent: Option<&str>) -> Result<winhttp::Handle, std::io::Error> {
+        use std::ptr::null;
+        use windows_sys::Win32::Networking::WinHttp::{
+            WinHttpOpen, WINHTTP_ACCESS_TYPE_AUTOMATIC_PROXY,
+        };
+
+        // Encode agent.
+        let agent = agent.map(|v| {
+            let mut v: Vec<u16> = v.encode_utf16().collect();
+            v.push(0);
+            v
+        });
+
+        // Create WinHTTP session.
+        let session = unsafe {
+            WinHttpOpen(
+                agent.map(|v| v.as_ptr()).unwrap_or(null()),
+                WINHTTP_ACCESS_TYPE_AUTOMATIC_PROXY,
+                null(),
+                null(),
+                0,
+            )
+        };
+
+        if session.is_null() {
+            Err(std::io::Error::last_os_error())
+        } else {
+            Ok(winhttp::Handle::new(session))
+        }
+    }
+}
+
+#[cfg(windows)]
+unsafe impl Send for HttpClient {}
+
+#[cfg(windows)]
+unsafe impl Sync for HttpClient {}
+
+/// Represents an error when [`HttpClient::new()`] fails.
+#[derive(Debug, Error)]
+pub enum NewError {
+    #[cfg(windows)]
+    #[error("couldn't create WinHTTP session")]
+    CreateWinHttpSessionFailed(#[source] std::io::Error),
+}
+
+/// Represents an error when [`HttpClient::request()`] fails.
+#[derive(Debug, Error)]
+pub enum RequestError {
+    #[error("the URL is not a HTTP URL")]
+    NotHttp,
+
+    #[error("the specified method is not supported")]
+    UnsupportedMethod,
+
+    #[cfg(windows)]
+    #[error("WinHttpConnect was failed")]
+    WinHttpConnectFailed(#[source] std::io::Error),
+
+    #[cfg(windows)]
+    #[error("WinHttpOpenRequest was failed")]
+    WinHttpOpenRequestFailed(#[source] std::io::Error),
+}
diff --git a/http/src/request.rs b/http/src/request.rs
new file mode 100644
index 0000000..91e5dbf
--- /dev/null
+++ b/http/src/request.rs
@@ -0,0 +1,181 @@
+use crate::{HttpClient, RequestError, Response};
+use http::Method;
+use std::{marker::PhantomData, rc::Rc};
+use thiserror::Error;
+use url::Url;
+
+/// HTTP request.
+pub struct Request<'a> {
+    #[cfg(unix)]
+    session: curl::easy::Easy2<Handler>,
+    #[cfg(windows)]
+    request: crate::winhttp::Handle, // Must be dropped before connection.
+    #[cfg(windows)]
+    connection: crate::winhttp::Handle, // Must be dropped last.
+    phantom: PhantomData<Rc<&'a HttpClient>>,
+}
+
+impl<'a> Request<'a> {
+    #[cfg(unix)]
+    pub(crate) fn new(method: Method, url: &Url) -> Result<Self, RequestError> {
+        use curl::easy::Easy2;
+
+        // Remove username and password.
+        let mut url = url.clone();
+
+        url.set_username("").unwrap();
+        url.set_password(None).unwrap();
+
+        // Create CURL session.
+        let mut session = Easy2::new(Handler {});
+
+        session.url(url.as_str()).unwrap();
+        session.follow_location(true).unwrap();
+
+        match method {
+            Method::DELETE | Method::PATCH => session.custom_request(method.as_str()).unwrap(),
+            Method::GET => session.get(true).unwrap(),
+            Method::POST => session.post(true).unwrap(),
+            Method::PUT => session.put(true).unwrap(),
+            _ => return Err(RequestError::UnsupportedMethod),
+        }
+
+        Ok(Self {
+            session,
+            phantom: PhantomData,
+        })
+    }
+
+    #[cfg(windows)]
+    pub(crate) fn new(
+        method: Method,
+        url: &Url,
+        session: &'a crate::winhttp::Handle,
+    ) -> Result<Self, RequestError> {
+        use std::io::Error;
+        use std::ptr::null;
+        use windows_sys::w;
+        use windows_sys::Win32::Networking::WinHttp::{
+            WinHttpConnect, WinHttpOpenRequest, WINHTTP_FLAG_ESCAPE_DISABLE,
+            WINHTTP_FLAG_ESCAPE_DISABLE_QUERY, WINHTTP_FLAG_SECURE,
+        };
+
+        // Get method.
+        let method = match method {
+            Method::DELETE => w!("DELETE"),
+            Method::GET => w!("GET"),
+            Method::PATCH => w!("PATCH"),
+            Method::POST => w!("POST"),
+            Method::PUT => w!("PUT"),
+            _ => return Err(RequestError::UnsupportedMethod),
+        };
+
+        // Is it possible for HTTP URL without host?
+        let host = url.host_str().unwrap();
+        let port = url.port_or_known_default().unwrap();
+        let secure = if url.scheme() == "https" {
+            WINHTTP_FLAG_SECURE
+        } else {
+            0
+        };
+
+        // Encode host.
+        let mut host: Vec<u16> = host.encode_utf16().collect();
+
+        host.push(0);
+
+        // Create connection handle.
+        let connection = unsafe { WinHttpConnect(session.get(), host.as_ptr(), port, 0) };
+
+        if connection.is_null() {
+            return Err(RequestError::WinHttpConnectFailed(Error::last_os_error()));
+        }
+
+        // Concat path and query.
+        let connection = unsafe { crate::winhttp::Handle::new(connection) };
+        let mut path = url.path().to_owned();
+
+        if let Some(v) = url.query() {
+            path.push('?');
+            path.push_str(v);
+        }
+
+        // Encode path.
+        let mut path: Vec<u16> = path.encode_utf16().collect();
+
+        path.push(0);
+
+        // Setup accept list.
+        let mut accept: Vec<*const u16> = Vec::new();
+
+        accept.push(w!("*/*"));
+        accept.push(null());
+
+        // Create request handle.
+        let request = unsafe {
+            WinHttpOpenRequest(
+                connection.get(),
+                method,
+                path.as_ptr(),
+                null(),
+                null(),
+                accept.as_ptr(),
+                WINHTTP_FLAG_ESCAPE_DISABLE | WINHTTP_FLAG_ESCAPE_DISABLE_QUERY | secure,
+            )
+        };
+
+        if request.is_null() {
+            Err(RequestError::WinHttpOpenRequestFailed(
+                Error::last_os_error(),
+            ))
+        } else {
+            Ok(Self {
+                request: unsafe { crate::winhttp::Handle::new(request) },
+                connection,
+            })
+        }
+    }
+
+    #[cfg(unix)]
+    pub fn send(self) -> Result<Response, SendError> {
+        // Execute the request.
+        self.session
+            .perform()
+            .map_err(SendError::CurlPerformFailed)?;
+
+        Ok(Response::new())
+    }
+
+    #[cfg(windows)]
+    pub fn send(self) -> Result<Response, SendError> {
+        use std::io::Error;
+        use std::ptr::null;
+        use windows_sys::Win32::Foundation::FALSE;
+        use windows_sys::Win32::Networking::WinHttp::WinHttpSendRequest;
+
+        if unsafe { WinHttpSendRequest(self.request.get(), null(), 0, null(), 0, 0, 0) } == FALSE {
+            return Err(SendError::WinHttpSendRequestFailed(Error::last_os_error()));
+        }
+
+        Ok(Response::new())
+    }
+}
+
+/// An implementation of [`curl::easy::Handler`].
+#[cfg(unix)]
+struct Handler {}
+
+#[cfg(unix)]
+impl curl::easy::Handler for Handler {}
+
+/// Represents an error when [`Request::send()`] fails.
+#[derive(Debug, Error)]
+pub enum SendError {
+    #[cfg(unix)]
+    #[error("curl_easy_perform was failed")]
+    CurlPerformFailed(#[source] curl::Error),
+
+    #[cfg(windows)]
+    #[error("WinHttpSendRequest was failed")]
+    WinHttpSendRequestFailed(#[source] std::io::Error),
+}
diff --git a/http/src/response.rs b/http/src/response.rs
new file mode 100644
index 0000000..f440504
--- /dev/null
+++ b/http/src/response.rs
@@ -0,0 +1,8 @@
+/// Response of a HTTP request.
+pub struct Response {}
+
+impl Response {
+    pub(crate) fn new() -> Self {
+        Self {}
+    }
+}
diff --git a/http/src/winhttp.rs b/http/src/winhttp.rs
new file mode 100644
index 0000000..dd71824
--- /dev/null
+++ b/http/src/winhttp.rs
@@ -0,0 +1,30 @@
+use std::ffi::c_void;
+use std::io::Error;
+use windows_sys::Win32::Foundation::FALSE;
+use windows_sys::Win32::Networking::WinHttp::WinHttpCloseHandle;
+
+/// Encapsulate a WinHTTP handle.
+pub struct Handle(*mut c_void);
+
+impl Handle {
+    /// # Safety
+    /// `raw` must be a valid WinHTTP handle.
+    pub(crate) unsafe fn new(raw: *mut c_void) -> Self {
+        Self(raw)
+    }
+
+    pub fn get(&self) -> *mut c_void {
+        self.0
+    }
+}
+
+impl Drop for Handle {
+    fn drop(&mut self) {
+        if unsafe { WinHttpCloseHandle(self.0) } == FALSE {
+            panic!(
+                "WinHttpCloseHandle() was failed: {}",
+                Error::last_os_error()
+            );
+        }
+    }
+}