diff --git a/.gitignore b/.gitignore
index db4709ed..69e162bf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,6 +14,7 @@ obj/
 xcuserdata/
 *.suo
 .idea/
-.vscode
+.vscode/
 *.iml
 test/dist/
+extension/native-messaging-host/build/
diff --git a/extension/native-messaging-host/.clang-format b/extension/native-messaging-host/.clang-format
new file mode 100644
index 00000000..be1ea221
--- /dev/null
+++ b/extension/native-messaging-host/.clang-format
@@ -0,0 +1,14 @@
+BasedOnStyle: LLVM
+IndentWidth: 4
+ColumnLimit: 100
+IncludeBlocks: Regroup
+IncludeCategories:
+  - Regex:           '^<ext/.*\.h>'
+    Priority:        2
+  - Regex:           '^<.*\.h>'
+    Priority:        1
+  - Regex:           '^<.*'
+    Priority:        2
+  - Regex:           '.*'
+    Priority:        3
+SortIncludes: true
\ No newline at end of file
diff --git a/extension/native-messaging-host/CMakeLists.txt b/extension/native-messaging-host/CMakeLists.txt
new file mode 100644
index 00000000..a9af8126
--- /dev/null
+++ b/extension/native-messaging-host/CMakeLists.txt
@@ -0,0 +1,30 @@
+cmake_minimum_required(VERSION 3.7)
+
+project(keeweb-native-messaging-host)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+include(FetchContent)
+
+FetchContent_Declare(
+    libuv
+    GIT_REPOSITORY https://github.com/libuv/libuv.git
+    GIT_TAG        v1.41.0
+)
+
+FetchContent_MakeAvailable(libuv)
+
+set(OUTPUT_NAME ${PROJECT_NAME})
+set(SOURCES src/main.cpp)
+
+add_executable(${PROJECT_NAME} ${SOURCES})
+
+target_link_libraries(${PROJECT_NAME} PRIVATE uv_a)
+target_include_directories(${PROJECT_NAME} PRIVATE ${libuv_SOURCE_DIR}/include)
+target_compile_options(${PROJECT_NAME} PRIVATE -Wall -Wextra -Wpedantic -Werror)
+
+if(CMAKE_BUILD_TYPE STREQUAL "Debug")
+    target_compile_options(${PROJECT_NAME} PRIVATE -fsanitize=address,undefined)
+    target_link_options(${PROJECT_NAME} PRIVATE -fsanitize=address,undefined)
+endif()
diff --git a/extension/native-messaging-host/Makefile b/extension/native-messaging-host/Makefile
new file mode 100644
index 00000000..b32ffeb1
--- /dev/null
+++ b/extension/native-messaging-host/Makefile
@@ -0,0 +1,13 @@
+all:
+	cmake -B build .
+	cmake --build build --config MinSizeRel
+
+debug:
+	cmake -B build .
+	cmake --build build --config Debug
+
+format:
+	clang-format -i src/*.cpp
+
+run:
+	echo -n 020000007b7d | xxd -r -p | build/keeweb-native-messaging-host chrome-extension://enjifmdnhaddmajefhfaoglcfdobkcpj
diff --git a/extension/native-messaging-host/src/main.cpp b/extension/native-messaging-host/src/main.cpp
new file mode 100644
index 00000000..e898f532
--- /dev/null
+++ b/extension/native-messaging-host/src/main.cpp
@@ -0,0 +1,208 @@
+#include <stdio.h>
+#include <uv.h>
+
+#include <algorithm>
+#include <array>
+#include <filesystem>
+#include <iostream>
+#include <queue>
+#include <vector>
+
+// https://developer.chrome.com/docs/apps/nativeMessaging/#native-messaging-host-protocol
+// https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Native_messaging#app_side
+
+struct State {
+    uv_stream_t *tty_in = nullptr;
+    uv_stream_t *tty_out = nullptr;
+    uv_stream_t *keeweb_pipe = nullptr;
+    std::queue<uv_buf_t *> pending_to_keeweb{};
+    std::queue<uv_buf_t *> pending_to_stdout{};
+    bool write_to_keeweb_in_progress = false;
+    bool write_to_stdout_in_progress = false;
+};
+
+State state{};
+
+constexpr std::array allowed_origins = {
+    std::string_view("chrome-extension://enjifmdnhaddmajefhfaoglcfdobkcpj")};
+
+void process_keeweb_queue();
+void process_stdout_queue();
+void close_keeweb_pipe();
+
+bool check_args(int argc, char *argv[]) {
+    if (argc < 2) {
+        std::cerr << "Expected origin";
+        return false;
+    }
+
+    std::string origin = argv[1];
+    auto found = std::find(allowed_origins.begin(), allowed_origins.end(), origin);
+    if (found == allowed_origins.end()) {
+        std::cerr << "Invalid origin";
+        return false;
+    }
+
+    return true;
+}
+
+void alloc_buf(uv_handle_t *, size_t size, uv_buf_t *buf) {
+    buf->base = new char[size];
+    buf->len = size;
+}
+
+void quit_after_stdio_error() {
+    if (state.keeweb_pipe) {
+        close_keeweb_pipe();
+    } else {
+        uv_read_stop(state.tty_in);
+        uv_loop_close(uv_default_loop());
+    }
+}
+
+void stdin_read_cb(uv_stream_t *, ssize_t nread, const uv_buf_t *buf) {
+    if (nread > 0) {
+        auto write_buf = new uv_buf_t{.base = buf->base, .len = static_cast<size_t>(nread)};
+        state.pending_to_keeweb.emplace(write_buf);
+        process_keeweb_queue();
+    } else if (nread < 0) {
+        quit_after_stdio_error();
+    }
+}
+
+void stdout_write_cb(uv_write_t *req, int status) {
+    delete req;
+
+    auto buf = state.pending_to_stdout.front();
+    state.pending_to_stdout.pop();
+    delete buf->base;
+    delete buf;
+
+    state.write_to_stdout_in_progress = false;
+
+    auto success = status >= 0;
+    if (success) {
+        process_stdout_queue();
+    } else {
+        quit_after_stdio_error();
+    }
+}
+
+void process_stdout_queue() {
+    if (state.write_to_stdout_in_progress || state.pending_to_stdout.empty()) {
+        return;
+    }
+    auto buf = state.pending_to_stdout.front();
+
+    auto write_req = new uv_write_t{};
+    uv_write(write_req, state.tty_out, buf, 1, stdout_write_cb);
+
+    state.write_to_stdout_in_progress = true;
+}
+
+void keeweb_pipe_close_cb(uv_handle_t *pipe) {
+    delete pipe;
+    uv_read_stop(state.tty_in);
+    uv_loop_close(uv_default_loop());
+}
+
+void close_keeweb_pipe() {
+    if (!state.keeweb_pipe) {
+        return;
+    }
+    auto pipe = state.keeweb_pipe;
+    state.keeweb_pipe = nullptr;
+    uv_read_stop(pipe);
+    uv_close(reinterpret_cast<uv_handle_t *>(pipe), keeweb_pipe_close_cb);
+}
+
+void keeweb_write_cb(uv_write_t *req, int status) {
+    delete req;
+
+    auto buf = state.pending_to_keeweb.front();
+    state.pending_to_keeweb.pop();
+    delete buf->base;
+    delete buf;
+
+    state.write_to_keeweb_in_progress = false;
+
+    auto success = status >= 0;
+    if (success) {
+        process_keeweb_queue();
+    } else {
+        close_keeweb_pipe();
+    }
+}
+
+void process_keeweb_queue() {
+    if (!state.keeweb_pipe || state.write_to_keeweb_in_progress ||
+        state.pending_to_keeweb.empty()) {
+        return;
+    }
+    auto buf = state.pending_to_keeweb.front();
+
+    auto write_req = new uv_write_t{};
+    uv_write(write_req, state.keeweb_pipe, buf, 1, keeweb_write_cb);
+
+    state.write_to_keeweb_in_progress = true;
+}
+
+void keeweb_pipe_read_cb(uv_stream_t *, ssize_t nread, const uv_buf_t *buf) {
+    if (nread > 0) {
+        auto write_buf = new uv_buf_t{.base = buf->base, .len = static_cast<size_t>(nread)};
+        state.pending_to_stdout.emplace(write_buf);
+        process_stdout_queue();
+    } else if (nread < 0) {
+        close_keeweb_pipe();
+    }
+}
+
+void keeweb_pipe_connect_cb(uv_connect_t *req, int status) {
+    auto pipe = req->handle;
+    delete req;
+    auto connected = status >= 0;
+    if (connected) {
+        state.keeweb_pipe = pipe;
+        uv_read_start(pipe, alloc_buf, keeweb_pipe_read_cb);
+        process_keeweb_queue();
+    } else {
+        std::cerr << "Cannot connect to KeeWeb";
+        // TODO: start KeeWeb
+    }
+}
+
+void connect_keeweb_pipe() {
+    auto temp_path = std::filesystem::temp_directory_path();
+    auto keeweb_pipe_path = temp_path / "keeweb-example.sock";
+    auto keeweb_pipe_name = keeweb_pipe_path.c_str();
+
+    auto keeweb_pipe = new uv_pipe_t{};
+    uv_pipe_init(uv_default_loop(), keeweb_pipe, false);
+
+    auto connect_req = new uv_connect_t();
+    uv_pipe_connect(connect_req, keeweb_pipe, keeweb_pipe_name, keeweb_pipe_connect_cb);
+}
+
+void start_reading_stdin() { uv_read_start(state.tty_in, alloc_buf, stdin_read_cb); }
+
+void init_tty() {
+    auto stdin_tty = new uv_tty_t{};
+    uv_tty_init(uv_default_loop(), stdin_tty, fileno(stdin), 0);
+    state.tty_in = reinterpret_cast<uv_stream_t *>(stdin_tty);
+
+    auto stdout_tty = new uv_tty_t{};
+    uv_tty_init(uv_default_loop(), stdout_tty, fileno(stdout), 0);
+    state.tty_out = reinterpret_cast<uv_stream_t *>(stdout_tty);
+}
+
+int main(int argc, char *argv[]) {
+    if (!check_args(argc, argv)) {
+        return 1;
+    }
+
+    init_tty();
+    start_reading_stdin();
+    connect_keeweb_pipe();
+
+    uv_run(uv_default_loop(), UV_RUN_DEFAULT);
+}
diff --git a/extension/native-messaging-host/test/native-host-test.js b/extension/native-messaging-host/test/native-host-test.js
new file mode 100644
index 00000000..98f5cdff
--- /dev/null
+++ b/extension/native-messaging-host/test/native-host-test.js
@@ -0,0 +1,18 @@
+const os = require('os');
+const net = require('net');
+const path = require('path');
+const fs = require('fs');
+
+const sockPath = path.join(os.tmpdir(), 'keeweb-example.sock');
+
+try {
+    fs.unlinkSync(sockPath);
+} catch {}
+
+const server = net.createServer((socket) => {
+    socket.on('data', (data) => {
+        socket.write(data);
+    });
+    socket.on('end', () => {});
+});
+server.listen(sockPath);