diff --git a/src/cdp/browser.zig b/src/cdp/browser.zig
new file mode 100644
index 00000000..ff20c329
--- /dev/null
+++ b/src/cdp/browser.zig
@@ -0,0 +1,77 @@
+const std = @import("std");
+
+const server = @import("../server.zig");
+const Ctx = server.CmdContext;
+const SendFn = server.SendFn;
+const result = @import("cdp.zig").result;
+const getParams = @import("cdp.zig").getParams;
+
+const BrowserMethods = enum {
+    getVersion,
+    setDownloadBehavior,
+};
+
+pub fn browser(
+    alloc: std.mem.Allocator,
+    id: u64,
+    action: []const u8,
+    scanner: *std.json.Scanner,
+    ctx: *Ctx,
+    comptime sendFn: SendFn,
+) ![]const u8 {
+    const method = std.meta.stringToEnum(BrowserMethods, action) orelse
+        return error.UnknownBrowserMethod;
+    return switch (method) {
+        .getVersion => browserGetVersion(alloc, id, scanner, ctx, sendFn),
+        .setDownloadBehavior => browserSetDownloadBehavior(alloc, id, scanner, ctx, sendFn),
+    };
+}
+
+const ProtocolVersion = "1.3";
+const Product = "Chrome/124.0.6367.29";
+const Revision = "@9e6ded5ac1ff5e38d930ae52bd9aec09bd1a68e4";
+const UserAgent = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36";
+const JsVersion = "12.4.254.8";
+
+fn browserGetVersion(
+    alloc: std.mem.Allocator,
+    id: u64,
+    _: *std.json.Scanner,
+    _: *Ctx,
+    comptime _: SendFn,
+) ![]const u8 {
+    const Res = struct {
+        protocolVersion: []const u8,
+        product: []const u8,
+        revision: []const u8,
+        userAgent: []const u8,
+        jsVersion: []const u8,
+    };
+
+    const res = Res{
+        .protocolVersion = ProtocolVersion,
+        .product = Product,
+        .revision = Revision,
+        .userAgent = UserAgent,
+        .jsVersion = JsVersion,
+    };
+    return result(alloc, id, Res, res);
+}
+
+fn browserSetDownloadBehavior(
+    alloc: std.mem.Allocator,
+    id: u64,
+    scanner: *std.json.Scanner,
+    _: *Ctx,
+    comptime _: SendFn,
+) ![]const u8 {
+    const Params = struct {
+        behavior: []const u8,
+        browserContextId: ?[]const u8 = null,
+        downloadPath: ?[]const u8 = null,
+        eventsEnabled: ?bool = null,
+    };
+    const params = try getParams(alloc, Params, scanner);
+    std.log.debug("params {any}", .{params});
+    return result(alloc, id, null, null);
+}
diff --git a/src/cdp/cdp.zig b/src/cdp/cdp.zig
new file mode 100644
index 00000000..7d33bc66
--- /dev/null
+++ b/src/cdp/cdp.zig
@@ -0,0 +1,87 @@
+const std = @import("std");
+
+const server = @import("../server.zig");
+const Ctx = server.CmdContext;
+const SendFn = server.SendFn;
+const browser = @import("browser.zig").browser;
+const target = @import("target.zig").target;
+
+const Domains = enum {
+    Browser,
+    Target,
+};
+
+// The caller is responsible for calling `free` on the returned slice.
+pub fn do(
+    alloc: std.mem.Allocator,
+    s: []const u8,
+    ctx: *Ctx,
+    comptime sendFn: SendFn,
+) ![]const u8 {
+    var scanner = std.json.Scanner.initCompleteInput(alloc, s);
+    defer scanner.deinit();
+
+    std.debug.assert(try scanner.next() == .object_begin);
+
+    try checkKey("id", (try scanner.next()).string);
+    const id = try std.fmt.parseUnsigned(u64, (try scanner.next()).number, 10);
+
+    try checkKey("method", (try scanner.next()).string);
+    const method = (try scanner.next()).string;
+
+    std.log.debug("cmd: id {any}, method {s}\n", .{ id, method });
+
+    var iter = std.mem.splitScalar(u8, method, '.');
+    const domain = std.meta.stringToEnum(Domains, iter.first()) orelse
+        return error.UnknonwDomain;
+
+    return switch (domain) {
+        .Browser => browser(alloc, id, iter.next().?, &scanner, ctx, sendFn),
+        .Target => target(alloc, id, iter.next().?, &scanner, ctx, sendFn),
+    };
+}
+
+// Utils
+// -----
+
+fn checkKey(key: []const u8, token: []const u8) !void {
+    if (!std.mem.eql(u8, key, token)) return error.WrongToken;
+}
+
+const resultNull = "{{\"id\": {d}, \"result\": {{}}}}";
+
+pub fn result(
+    alloc: std.mem.Allocator,
+    id: u64,
+    comptime T: ?type,
+    res: anytype,
+) ![]const u8 {
+    if (T == null) return try std.fmt.allocPrint(alloc, resultNull, .{id});
+
+    const Resp = struct {
+        id: u64,
+        result: T.?,
+    };
+    const resp = Resp{ .id = id, .result = res };
+
+    var out = std.ArrayList(u8).init(alloc);
+    defer out.deinit();
+
+    try std.json.stringify(resp, .{}, out.writer());
+    const ret = try alloc.alloc(u8, out.items.len);
+    @memcpy(ret, out.items);
+    return ret;
+}
+
+pub fn getParams(
+    alloc: std.mem.Allocator,
+    comptime T: type,
+    scanner: *std.json.Scanner,
+) !T {
+    try checkKey("params", (try scanner.next()).string);
+    const options = std.json.ParseOptions{
+        .max_value_len = scanner.input.len,
+        .allocate = .alloc_if_needed,
+    };
+    return std.json.innerParse(T, alloc, scanner, options);
+}
diff --git a/src/cdp/target.zig b/src/cdp/target.zig
new file mode 100644
index 00000000..cf861086
--- /dev/null
+++ b/src/cdp/target.zig
@@ -0,0 +1,100 @@
+const std = @import("std");
+
+const server = @import("../server.zig");
+const Ctx = server.CmdContext;
+const SendFn = server.SendFn;
+const result = @import("cdp.zig").result;
+const getParams = @import("cdp.zig").getParams;
+
+const TargetMethods = enum {
+    setAutoAttach,
+    // attachedToTarget,
+    // getTargetInfo,
+};
+
+pub fn target(
+    alloc: std.mem.Allocator,
+    id: u64,
+    action: []const u8,
+    scanner: *std.json.Scanner,
+    ctx: *Ctx,
+    comptime sendFn: SendFn,
+) ![]const u8 {
+    const method = std.meta.stringToEnum(TargetMethods, action) orelse
+        return error.UnknownTargetMethod;
+    return switch (method) {
+        .setAutoAttach => tagetSetAutoAttach(alloc, id, scanner, ctx, sendFn),
+        // .getTargetInfo => tagetGetTargetInfo(alloc, id, scanner),
+    };
+}
+
+fn tagetSetAutoAttach(
+    alloc: std.mem.Allocator,
+    id: u64,
+    scanner: *std.json.Scanner,
+    _: *Ctx,
+    comptime _: SendFn,
+) ![]const u8 {
+    const Params = struct {
+        autoAttach: bool,
+        waitForDebuggerOnStart: bool,
+        flatten: ?bool = null,
+    };
+    const params = try getParams(alloc, Params, scanner);
+    std.log.debug("params {any}", .{params});
+    return result(alloc, id, null, null);
+}
+
+const TargetID = "CFCD6EC01573CF29BB638E9DC0F52DDC";
+
+fn tagetGetTargetInfo(
+    alloc: std.mem.Allocator,
+    id: u64,
+    scanner: *std.json.Scanner,
+    _: *Ctx,
+    comptime _: SendFn,
+) ![]const u8 {
+    _ = scanner;
+
+    const TargetInfo = struct {
+        targetId: []const u8,
+        type: []const u8,
+        title: []const u8,
+        url: []const u8,
+        attached: bool,
+        canAccessOpener: bool,
+
+        browserContextId: ?[]const u8 = null,
+    };
+    const targetInfo = TargetInfo{
+        .targetId = TargetID,
+        .type = "page",
+    };
+    _ = targetInfo;
+    return result(alloc, id, null, null);
+}
+
+// fn tagetGetTargetInfo(
+//     alloc: std.mem.Allocator,
+//     id: u64,
+//     scanner: *std.json.Scanner,
+// ) ![]const u8 {
+//     _ = scanner;
+
+//     const TargetInfo = struct {
+//         targetId: []const u8,
+//         type: []const u8,
+//         title: []const u8,
+//         url: []const u8,
+//         attached: bool,
+//         canAccessOpener: bool,
+
+//         browserContextId: ?[]const u8 = null,
+//     };
+//     const targetInfo = TargetInfo{
+//         .targetId = TargetID,
+//         .type = "page",
+//     };
+//     _ = targetInfo;
+//     return result(alloc, id, null, null);
+// }
diff --git a/src/main.zig b/src/main.zig
index 40b513fe..5575f815 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -20,57 +20,16 @@ const std = @import("std");
 
 const jsruntime = @import("jsruntime");
 
+const server = @import("server.zig");
+
 const parser = @import("netsurf");
 const apiweb = @import("apiweb.zig");
-const Window = @import("html/window.zig").Window;
 
 pub const Types = jsruntime.reflect(apiweb.Interfaces);
 pub const UserContext = apiweb.UserContext;
 
 const socket_path = "/tmp/browsercore-server.sock";
 
-var doc: *parser.DocumentHTML = undefined;
-var server: std.net.Server = undefined;
-
-fn execJS(
-    alloc: std.mem.Allocator,
-    js_env: *jsruntime.Env,
-) anyerror!void {
-    // start JS env
-    try js_env.start();
-    defer js_env.stop();
-
-    // alias global as self and window
-    var window = Window.create(null);
-    window.replaceDocument(doc);
-    try js_env.bindGlobal(window);
-
-    // try catch
-    var try_catch: jsruntime.TryCatch = undefined;
-    try_catch.init(js_env.*);
-    defer try_catch.deinit();
-
-    while (true) {
-
-        // read cmd
-        const conn = try server.accept();
-        var buf: [100]u8 = undefined;
-        const read = try conn.stream.read(&buf);
-        const cmd = buf[0..read];
-        std.debug.print("<- {s}\n", .{cmd});
-        if (std.mem.eql(u8, cmd, "exit")) {
-            break;
-        }
-
-        const res = try js_env.exec(cmd, "cdp");
-        const res_str = try res.toString(alloc, js_env.*);
-        defer alloc.free(res_str);
-        std.debug.print("-> {s}\n", .{res_str});
-
-        _ = try conn.stream.write(res_str);
-    }
-}
-
 pub fn main() !void {
 
     // create v8 vm
@@ -81,18 +40,6 @@ pub fn main() !void {
     var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
     defer arena.deinit();
 
-    try parser.init();
-    defer parser.deinit();
-
-    // document
-    const file = try std.fs.cwd().openFile("test.html", .{});
-    defer file.close();
-
-    doc = try parser.documentHTMLParse(file.reader(), "UTF-8");
-    defer parser.documentHTMLClose(doc) catch |err| {
-        std.debug.print("documentHTMLClose error: {s}\n", .{@errorName(err)});
-    };
-
     // remove socket file of internal server
     // reuse_address (SO_REUSEADDR flag) does not seems to work on unix socket
     // see: https://gavv.net/articles/unix-socket-reuse/
@@ -105,9 +52,15 @@ pub fn main() !void {
 
     // server
     const addr = try std.net.Address.initUnix(socket_path);
-    server = try addr.listen(.{});
-    defer server.deinit();
+    var srv = std.net.StreamServer.init(.{
+        .reuse_address = true,
+        .reuse_port = true,
+        .force_nonblocking = true,
+    });
+    defer srv.deinit();
+    try srv.listen(addr);
     std.debug.print("Listening on: {s}...\n", .{socket_path});
+    server.socket_fd = srv.sockfd.?;
 
-    try jsruntime.loadEnv(&arena, null, execJS);
+    try jsruntime.loadEnv(&arena, server.execJS);
 }
diff --git a/src/server.zig b/src/server.zig
new file mode 100644
index 00000000..47d3abba
--- /dev/null
+++ b/src/server.zig
@@ -0,0 +1,231 @@
+const std = @import("std");
+
+const public = @import("jsruntime");
+
+const Window = @import("html/window.zig").Window;
+
+const cdp = @import("cdp/cdp.zig");
+pub var socket_fd: std.os.socket_t = undefined;
+
+// I/O input command context
+pub const CmdContext = struct {
+    alloc: std.mem.Allocator,
+    js_env: *public.Env,
+    socket: std.os.socket_t,
+    completion: *public.IO.Completion,
+    buf: []u8,
+    close: bool = false,
+
+    try_catch: public.TryCatch,
+
+    // cmds: cdp.Cmds,
+};
+
+fn respCallback(
+    ctx: *CmdContext,
+    _: *public.IO.Completion,
+    result: public.IO.SendError!usize,
+) void {
+    _ = result catch |err| {
+        ctx.close = true;
+        std.debug.print("send error: {s}\n", .{@errorName(err)});
+        return;
+    };
+    std.log.debug("send ok", .{});
+}
+
+pub const SendFn = (fn (*CmdContext, []const u8) anyerror!void);
+
+fn osSend(ctx: *CmdContext, msg: []const u8) !void {
+    const s = try std.os.write(ctx.socket, msg);
+    std.log.debug("send ok {d}", .{s});
+}
+
+fn loopSend(ctx: *CmdContext, msg: []const u8) !void {
+    ctx.js_env.nat_ctx.loop.io.send(
+        *CmdContext,
+        ctx,
+        respCallback,
+        ctx.completion,
+        ctx.socket,
+        msg,
+    );
+}
+
+// I/O input command callback
+fn cmdCallback(
+    ctx: *CmdContext,
+    completion: *public.IO.Completion,
+    result: public.IO.RecvError!usize,
+) void {
+    const size = result catch |err| {
+        ctx.close = true;
+        std.debug.print("recv error: {s}\n", .{@errorName(err)});
+        return;
+    };
+
+    const input = ctx.buf[0..size];
+
+    // close on exit command
+    if (std.mem.eql(u8, input, "exit")) {
+        ctx.close = true;
+        return;
+    }
+
+    // continue receving messages asynchronously
+    defer {
+        ctx.js_env.nat_ctx.loop.io.recv(
+            *CmdContext,
+            ctx,
+            cmdCallback,
+            completion,
+            ctx.socket,
+            ctx.buf,
+        );
+    }
+
+    std.debug.print("input {s}\n", .{input});
+    const res = cdp.do(ctx.alloc, input, ctx, osSend) catch |err| {
+        std.log.debug("error: {any}\n", .{err});
+        loopSend(ctx, "{}") catch unreachable;
+        // TODO: return proper error
+        return;
+    };
+    defer ctx.alloc.free(res);
+    std.log.debug("res {s}", .{res});
+
+    osSend(ctx, res) catch unreachable;
+
+    // ctx.js_env.nat_ctx.loop.io.send(
+    //     *CmdContext,
+    //     ctx,
+    //     respCallback,
+    //     completion,
+    //     ctx.socket,
+    //     res,
+    // );
+
+    // JS execute
+    // const res = ctx.js_env.exec(
+    //     ctx.alloc,
+    //     input,
+    //     "shell.js",
+    //     ctx.try_catch,
+    // ) catch |err| {
+    //     ctx.close = true;
+    //     std.debug.print("JS exec error: {s}\n", .{@errorName(err)});
+    //     return;
+    // };
+    // defer res.deinit(ctx.alloc);
+
+    // // JS print result
+    // if (res.success) {
+    //     if (std.mem.eql(u8, res.result, "undefined")) {
+    //         std.debug.print("<- \x1b[38;5;242m{s}\x1b[0m\n", .{res.result});
+    //     } else {
+    //         std.debug.print("<- \x1b[33m{s}\x1b[0m\n", .{res.result});
+    //     }
+    // } else {
+    //     std.debug.print("{s}\n", .{res.result});
+    // }
+
+    // acknowledge to repl result has been printed
+    // _ = std.os.write(ctx.socket, "ok") catch unreachable;
+}
+
+// I/O connection context
+const ConnContext = struct {
+    socket: std.os.socket_t,
+
+    cmdContext: *CmdContext,
+};
+
+// I/O connection callback
+fn connCallback(
+    ctx: *ConnContext,
+    completion: *public.IO.Completion,
+    result: public.IO.AcceptError!std.os.socket_t,
+) void {
+    ctx.cmdContext.socket = result catch |err| @panic(@errorName(err));
+
+    // launch receving messages asynchronously
+    ctx.cmdContext.js_env.nat_ctx.loop.io.recv(
+        *CmdContext,
+        ctx.cmdContext,
+        cmdCallback,
+        completion,
+        ctx.cmdContext.socket,
+        ctx.cmdContext.buf,
+    );
+}
+
+pub fn execJS(
+    alloc: std.mem.Allocator,
+    js_env: *public.Env,
+) anyerror!void {
+
+    // start JS env
+    try js_env.start(alloc);
+    defer js_env.stop();
+
+    // alias global as self
+    try js_env.attachObject(try js_env.getGlobal(), "self", null);
+
+    // alias global as self and window
+    const window = Window.create(null);
+    // window.replaceDocument(doc); TODO
+    try js_env.bindGlobal(window);
+
+    // add console object
+    const console = public.Console{};
+    try js_env.addObject(console, "console");
+
+    // JS try cache
+    var try_catch = public.TryCatch.init(js_env.*);
+    defer try_catch.deinit();
+
+    // create I/O contexts and callbacks
+    // for accepting connections and receving messages
+    var completion: public.IO.Completion = undefined;
+    var input: [1024]u8 = undefined;
+    var cmd_ctx = CmdContext{
+        .alloc = alloc,
+        .js_env = js_env,
+        .socket = undefined,
+        .buf = &input,
+        .try_catch = try_catch,
+        .completion = &completion,
+        // .cmds = .{},
+    };
+    var conn_ctx = ConnContext{
+        .socket = socket_fd,
+        .cmdContext = &cmd_ctx,
+    };
+
+    // launch accepting connection asynchronously on internal server
+    const loop = js_env.nat_ctx.loop;
+    loop.io.accept(
+        *ConnContext,
+        &conn_ctx,
+        connCallback,
+        &completion,
+        socket_fd,
+    );
+
+    // infinite loop on I/O events, either:
+    // - cmd from incoming connection on server socket
+    // - JS callbacks events from scripts
+    while (true) {
+        try loop.io.tick();
+        if (loop.cbk_error) {
+            if (try try_catch.exception(alloc, js_env.*)) |msg| {
+                std.debug.print("\n\rUncaught {s}\n\r", .{msg});
+                alloc.free(msg);
+            }
+            loop.cbk_error = false;
+        }
+        if (cmd_ctx.close) {
+            break;
+        }
+    }
+}