diff --git a/Cargo.lock b/Cargo.lock
index 80eb45ffbd..c46c6ac9fb 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -591,6 +591,14 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "deno_broadcast_channel"
+version = "0.1.0"
+dependencies = [
+ "deno_core",
+ "tokio",
+]
+
 [[package]]
 name = "deno_console"
 version = "0.7.0"
@@ -691,6 +699,7 @@ version = "0.15.0"
 dependencies = [
  "atty",
  "bytes",
+ "deno_broadcast_channel",
  "deno_console",
  "deno_core",
  "deno_crypto",
diff --git a/Cargo.toml b/Cargo.toml
index 31e2ee0915..98ea64293c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,7 @@ members = [
   "serde_v8",
   "test_plugin",
   "test_util",
+  "extensions/broadcast_channel",
   "extensions/console",
   "extensions/crypto",
   "extensions/fetch",
diff --git a/cli/build.rs b/cli/build.rs
index 116ce8167a..ab2a7d0f7d 100644
--- a/cli/build.rs
+++ b/cli/build.rs
@@ -8,6 +8,7 @@ use deno_core::serde_json::json;
 use deno_core::serde_json::Value;
 use deno_core::JsRuntime;
 use deno_core::RuntimeOptions;
+use deno_runtime::deno_broadcast_channel;
 use deno_runtime::deno_console;
 use deno_runtime::deno_crypto;
 use deno_runtime::deno_fetch;
@@ -74,6 +75,10 @@ fn create_compiler_snapshot(
   op_crate_libs.insert("deno.websocket", deno_websocket::get_declaration());
   op_crate_libs.insert("deno.webstorage", deno_webstorage::get_declaration());
   op_crate_libs.insert("deno.crypto", deno_crypto::get_declaration());
+  op_crate_libs.insert(
+    "deno.broadcast_channel",
+    deno_broadcast_channel::get_declaration(),
+  );
 
   // ensure we invalidate the build properly.
   for (_, path) in op_crate_libs.iter() {
@@ -300,6 +305,10 @@ fn main() {
     "cargo:rustc-env=DENO_CRYPTO_LIB_PATH={}",
     deno_crypto::get_declaration().display()
   );
+  println!(
+    "cargo:rustc-env=DENO_BROADCAST_CHANNEL_LIB_PATH={}",
+    deno_broadcast_channel::get_declaration().display()
+  );
 
   println!("cargo:rustc-env=TARGET={}", env::var("TARGET").unwrap());
   println!("cargo:rustc-env=PROFILE={}", env::var("PROFILE").unwrap());
diff --git a/cli/main.rs b/cli/main.rs
index aa144d1ded..868805e926 100644
--- a/cli/main.rs
+++ b/cli/main.rs
@@ -302,7 +302,7 @@ fn print_cache_info(
 
 pub fn get_types(unstable: bool) -> String {
   let mut types = format!(
-    "{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}",
+    "{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}",
     crate::tsc::DENO_NS_LIB,
     crate::tsc::DENO_CONSOLE_LIB,
     crate::tsc::DENO_URL_LIB,
@@ -313,6 +313,7 @@ pub fn get_types(unstable: bool) -> String {
     crate::tsc::DENO_WEBSOCKET_LIB,
     crate::tsc::DENO_WEBSTORAGE_LIB,
     crate::tsc::DENO_CRYPTO_LIB,
+    crate::tsc::DENO_BROADCAST_CHANNEL_LIB,
     crate::tsc::SHARED_GLOBALS_LIB,
     crate::tsc::WINDOW_LIB,
   );
diff --git a/cli/tsc.rs b/cli/tsc.rs
index 6d2e297db8..203bf794b0 100644
--- a/cli/tsc.rs
+++ b/cli/tsc.rs
@@ -41,6 +41,8 @@ pub static DENO_WEBSOCKET_LIB: &str =
 pub static DENO_WEBSTORAGE_LIB: &str =
   include_str!(env!("DENO_WEBSTORAGE_LIB_PATH"));
 pub static DENO_CRYPTO_LIB: &str = include_str!(env!("DENO_CRYPTO_LIB_PATH"));
+pub static DENO_BROADCAST_CHANNEL_LIB: &str =
+  include_str!(env!("DENO_BROADCAST_CHANNEL_LIB_PATH"));
 pub static SHARED_GLOBALS_LIB: &str =
   include_str!("dts/lib.deno.shared_globals.d.ts");
 pub static WINDOW_LIB: &str = include_str!("dts/lib.deno.window.d.ts");
diff --git a/extensions/broadcast_channel/01_broadcast_channel.js b/extensions/broadcast_channel/01_broadcast_channel.js
new file mode 100644
index 0000000000..34f8b9e196
--- /dev/null
+++ b/extensions/broadcast_channel/01_broadcast_channel.js
@@ -0,0 +1,117 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+"use strict";
+
+((window) => {
+  const core = window.Deno.core;
+  const webidl = window.__bootstrap.webidl;
+
+  const handlerSymbol = Symbol("eventHandlers");
+  function makeWrappedHandler(handler) {
+    function wrappedHandler(...args) {
+      if (typeof wrappedHandler.handler !== "function") {
+        return;
+      }
+      return wrappedHandler.handler.call(this, ...args);
+    }
+    wrappedHandler.handler = handler;
+    return wrappedHandler;
+  }
+  // TODO(lucacasonato) reuse when we can reuse code between web crates
+  function defineEventHandler(emitter, name) {
+    // HTML specification section 8.1.5.1
+    Object.defineProperty(emitter, `on${name}`, {
+      get() {
+        return this[handlerSymbol]?.get(name)?.handler;
+      },
+      set(value) {
+        if (!this[handlerSymbol]) {
+          this[handlerSymbol] = new Map();
+        }
+        let handlerWrapper = this[handlerSymbol]?.get(name);
+        if (handlerWrapper) {
+          handlerWrapper.handler = value;
+        } else {
+          handlerWrapper = makeWrappedHandler(value);
+          this.addEventListener(name, handlerWrapper);
+        }
+        this[handlerSymbol].set(name, handlerWrapper);
+      },
+      configurable: true,
+      enumerable: true,
+    });
+  }
+
+  const _name = Symbol("[[name]]");
+  const _closed = Symbol("[[closed]]");
+  const _rid = Symbol("[[rid]]");
+
+  class BroadcastChannel extends EventTarget {
+    [_name];
+    [_closed] = false;
+    [_rid];
+
+    get name() {
+      return this[_name];
+    }
+
+    constructor(name) {
+      super();
+
+      window.location;
+
+      const prefix = "Failed to construct 'broadcastChannel'";
+      webidl.requiredArguments(arguments.length, 1, { prefix });
+
+      this[_name] = webidl.converters["DOMString"](name, {
+        prefix,
+        context: "Argument 1",
+      });
+
+      this[_rid] = core.opSync("op_broadcast_open", this[_name]);
+
+      this[webidl.brand] = webidl.brand;
+
+      this.#eventLoop();
+    }
+
+    postMessage(message) {
+      webidl.assertBranded(this, BroadcastChannel);
+
+      if (this[_closed]) {
+        throw new DOMException("Already closed", "InvalidStateError");
+      }
+
+      core.opAsync("op_broadcast_send", this[_rid], core.serialize(message));
+    }
+
+    close() {
+      webidl.assertBranded(this, BroadcastChannel);
+
+      this[_closed] = true;
+      core.close(this[_rid]);
+    }
+
+    async #eventLoop() {
+      while (!this[_closed]) {
+        const message = await core.opAsync(
+          "op_broadcast_next_event",
+          this[_rid],
+        );
+
+        if (message.length !== 0) {
+          const event = new MessageEvent("message", {
+            data: core.deserialize(message),
+            origin: window.location,
+          });
+          event.target = this;
+          this.dispatchEvent(event);
+        }
+      }
+    }
+  }
+
+  defineEventHandler(BroadcastChannel.prototype, "message");
+  defineEventHandler(BroadcastChannel.prototype, "messageerror");
+
+  window.__bootstrap.broadcastChannel = { BroadcastChannel };
+})(this);
diff --git a/extensions/broadcast_channel/Cargo.toml b/extensions/broadcast_channel/Cargo.toml
new file mode 100644
index 0000000000..72c29f651f
--- /dev/null
+++ b/extensions/broadcast_channel/Cargo.toml
@@ -0,0 +1,18 @@
+# Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+[package]
+name = "deno_broadcast_channel"
+version = "0.1.0"
+edition = "2018"
+description = "Implementation of BroadcastChannel API for Deno"
+authors = ["the Deno authors"]
+license = "MIT"
+readme = "README.md"
+repository = "https://github.com/denoland/deno"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+deno_core = { version = "0.88.0", path = "../../core" }
+tokio = { version = "1.4.0", features = ["full"] }
diff --git a/extensions/broadcast_channel/README.md b/extensions/broadcast_channel/README.md
new file mode 100644
index 0000000000..5b5034ef7a
--- /dev/null
+++ b/extensions/broadcast_channel/README.md
@@ -0,0 +1,5 @@
+# deno_broadcast_channel
+
+This crate implements the BroadcastChannel functions of Deno.
+
+Spec: https://html.spec.whatwg.org/multipage/web-messaging.html
diff --git a/extensions/broadcast_channel/lib.deno_broadcast_channel.d.ts b/extensions/broadcast_channel/lib.deno_broadcast_channel.d.ts
new file mode 100644
index 0000000000..c8efef778a
--- /dev/null
+++ b/extensions/broadcast_channel/lib.deno_broadcast_channel.d.ts
@@ -0,0 +1,55 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+// deno-lint-ignore-file no-explicit-any
+
+/// <reference no-default-lib="true" />
+/// <reference lib="esnext" />
+
+interface BroadcastChannelEventMap {
+  "message": MessageEvent;
+  "messageerror": MessageEvent;
+}
+
+interface BroadcastChannel extends EventTarget {
+  /**
+   * Returns the channel name (as passed to the constructor).
+   */
+  readonly name: string;
+  onmessage: ((this: BroadcastChannel, ev: MessageEvent) => any) | null;
+  onmessageerror: ((this: BroadcastChannel, ev: MessageEvent) => any) | null;
+  /**
+   * Closes the BroadcastChannel object, opening it up to garbage collection.
+   */
+  close(): void;
+  /**
+   * Sends the given message to other BroadcastChannel objects set up for
+   * this channel. Messages can be structured objects, e.g. nested objects
+   * and arrays.
+   */
+  postMessage(message: any): void;
+  addEventListener<K extends keyof BroadcastChannelEventMap>(
+    type: K,
+    listener: (this: BroadcastChannel, ev: BroadcastChannelEventMap[K]) => any,
+    options?: boolean | AddEventListenerOptions,
+  ): void;
+  addEventListener(
+    type: string,
+    listener: EventListenerOrEventListenerObject,
+    options?: boolean | AddEventListenerOptions,
+  ): void;
+  removeEventListener<K extends keyof BroadcastChannelEventMap>(
+    type: K,
+    listener: (this: BroadcastChannel, ev: BroadcastChannelEventMap[K]) => any,
+    options?: boolean | EventListenerOptions,
+  ): void;
+  removeEventListener(
+    type: string,
+    listener: EventListenerOrEventListenerObject,
+    options?: boolean | EventListenerOptions,
+  ): void;
+}
+
+declare var BroadcastChannel: {
+  prototype: BroadcastChannel;
+  new (name: string): BroadcastChannel;
+};
diff --git a/extensions/broadcast_channel/lib.rs b/extensions/broadcast_channel/lib.rs
new file mode 100644
index 0000000000..cee9c3e0c1
--- /dev/null
+++ b/extensions/broadcast_channel/lib.rs
@@ -0,0 +1,131 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+use deno_core::error::bad_resource_id;
+use deno_core::error::AnyError;
+use deno_core::include_js_files;
+use deno_core::op_async;
+use deno_core::op_sync;
+use deno_core::AsyncRefCell;
+use deno_core::Extension;
+use deno_core::OpState;
+use deno_core::RcRef;
+use deno_core::Resource;
+use deno_core::ResourceId;
+use deno_core::ZeroCopyBuf;
+use std::borrow::Cow;
+use std::cell::RefCell;
+use std::path::PathBuf;
+use std::rc::Rc;
+use tokio::io::AsyncReadExt;
+use tokio::io::AsyncWriteExt;
+
+struct BroadcastChannelResource(AsyncRefCell<tokio::fs::File>);
+
+impl Resource for BroadcastChannelResource {
+  fn name(&self) -> Cow<str> {
+    "broadcastChannel".into()
+  }
+}
+
+pub fn op_broadcast_open(
+  state: &mut OpState,
+  name: String,
+  _bufs: Option<ZeroCopyBuf>,
+) -> Result<ResourceId, AnyError> {
+  let path = PathBuf::from("./");
+  std::fs::create_dir_all(&path)?;
+  let file = std::fs::OpenOptions::new()
+    .create(true)
+    .append(true)
+    .read(true)
+    .open(path.join(format!("broadcast_{}", name)))?;
+
+  let rid =
+    state
+      .resource_table
+      .add(BroadcastChannelResource(AsyncRefCell::new(
+        tokio::fs::File::from_std(file),
+      )));
+
+  Ok(rid)
+}
+
+pub async fn op_broadcast_send(
+  state: Rc<RefCell<OpState>>,
+  rid: ResourceId,
+  buf: Option<ZeroCopyBuf>,
+) -> Result<(), AnyError> {
+  let state = state.borrow_mut();
+  let resource = state
+    .resource_table
+    .get::<BroadcastChannelResource>(rid)
+    .ok_or_else(bad_resource_id)?;
+
+  let mut file = RcRef::map(&resource, |r| &r.0).borrow_mut().await;
+
+  let buffer_data = buf.unwrap();
+  let mut data = vec![];
+  data.extend_from_slice(&(buffer_data.len() as u64).to_ne_bytes());
+  data.extend_from_slice(&buffer_data);
+
+  file.write_all(&data).await?;
+
+  Ok(())
+}
+
+pub async fn op_broadcast_next_event(
+  state: Rc<RefCell<OpState>>,
+  rid: ResourceId,
+  _bufs: Option<ZeroCopyBuf>,
+) -> Result<Vec<u8>, AnyError> {
+  let resource = {
+    let state = state.borrow_mut();
+    state
+      .resource_table
+      .get::<BroadcastChannelResource>(rid)
+      .ok_or_else(bad_resource_id)?
+  };
+
+  let mut file = RcRef::map(&resource, |r| &r.0).borrow_mut().await;
+
+  let size = match file.read_u64().await {
+    Ok(s) => s,
+    Err(e) => {
+      return match e.kind() {
+        deno_core::futures::io::ErrorKind::UnexpectedEof => Ok(vec![]),
+        _ => Err(e.into()),
+      }
+    }
+  };
+  let mut data = vec![0u8; size as usize];
+  match file.read_exact(&mut data).await {
+    Ok(s) => s,
+    Err(e) => {
+      return match e.kind() {
+        deno_core::futures::io::ErrorKind::UnexpectedEof => Ok(vec![]),
+        _ => Err(e.into()),
+      }
+    }
+  };
+
+  Ok(data)
+}
+
+pub fn init() -> Extension {
+  Extension::builder()
+    .js(include_js_files!(
+      prefix "deno:extensions/broadcast_channel",
+      "01_broadcast_channel.js",
+    ))
+    .ops(vec![
+      ("op_broadcast_open", op_sync(op_broadcast_open)),
+      ("op_broadcast_send", op_async(op_broadcast_send)),
+      ("op_broadcast_next_event", op_async(op_broadcast_next_event)),
+    ])
+    .build()
+}
+
+pub fn get_declaration() -> PathBuf {
+  PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+    .join("lib.deno_broadcast_channel.d.ts")
+}
diff --git a/runtime/Cargo.toml b/runtime/Cargo.toml
index 5758219d80..c7805b1b16 100644
--- a/runtime/Cargo.toml
+++ b/runtime/Cargo.toml
@@ -18,6 +18,7 @@ name = "hello_runtime"
 path = "examples/hello_runtime.rs"
 
 [build-dependencies]
+deno_broadcast_channel = { path = "../extensions/broadcast_channel", version = "0.1.0" }
 deno_console = { version = "0.7.0", path = "../extensions/console" }
 deno_core = { version = "0.88.0", path = "../core" }
 deno_crypto = { version = "0.21.0", path = "../extensions/crypto" }
@@ -36,6 +37,7 @@ winres = "0.1.11"
 winapi = "0.3.9"
 
 [dependencies]
+deno_broadcast_channel = { path = "../extensions/broadcast_channel", version = "0.1.0" }
 deno_console = { version = "0.7.0", path = "../extensions/console" }
 deno_core = { version = "0.88.0", path = "../core" }
 deno_crypto = { version = "0.21.0", path = "../extensions/crypto" }
diff --git a/runtime/build.rs b/runtime/build.rs
index e1cae71954..4fe89af3ec 100644
--- a/runtime/build.rs
+++ b/runtime/build.rs
@@ -52,6 +52,7 @@ fn create_runtime_snapshot(snapshot_path: &Path, files: Vec<PathBuf>) {
     deno_crypto::init(None),
     deno_webgpu::init(false),
     deno_timers::init::<deno_timers::NoTimersPermission>(),
+    deno_broadcast_channel::init(),
   ];
 
   let js_runtime = JsRuntime::new(RuntimeOptions {
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index 796d5178f3..e1c474c282 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -29,6 +29,7 @@ delete Object.prototype.__proto__;
   const webgpu = window.__bootstrap.webgpu;
   const webSocket = window.__bootstrap.webSocket;
   const webStorage = window.__bootstrap.webStorage;
+  const broadcastChannel = window.__bootstrap.broadcastChannel;
   const file = window.__bootstrap.file;
   const formData = window.__bootstrap.formData;
   const fetch = window.__bootstrap.fetch;
@@ -282,6 +283,7 @@ delete Object.prototype.__proto__;
     URL: util.nonEnumerable(url.URL),
     URLSearchParams: util.nonEnumerable(url.URLSearchParams),
     WebSocket: util.nonEnumerable(webSocket.WebSocket),
+    BroadcastChannel: util.nonEnumerable(broadcastChannel.BroadcastChannel),
     Worker: util.nonEnumerable(worker.Worker),
     WritableStream: util.nonEnumerable(streams.WritableStream),
     WritableStreamDefaultWriter: util.nonEnumerable(
diff --git a/runtime/lib.rs b/runtime/lib.rs
index d45a727275..3cc73bffff 100644
--- a/runtime/lib.rs
+++ b/runtime/lib.rs
@@ -1,5 +1,6 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 
+pub use deno_broadcast_channel;
 pub use deno_console;
 pub use deno_crypto;
 pub use deno_fetch;
diff --git a/runtime/web_worker.rs b/runtime/web_worker.rs
index 5b731a0f51..172d24dea2 100644
--- a/runtime/web_worker.rs
+++ b/runtime/web_worker.rs
@@ -268,6 +268,7 @@ impl WebWorker {
         options.user_agent.clone(),
         options.ca_data.clone(),
       ),
+      deno_broadcast_channel::init(),
       deno_crypto::init(options.seed),
       deno_webgpu::init(options.unstable),
       deno_timers::init::<Permissions>(),
diff --git a/runtime/worker.rs b/runtime/worker.rs
index c75f09dc81..b41f0291c5 100644
--- a/runtime/worker.rs
+++ b/runtime/worker.rs
@@ -107,6 +107,7 @@ impl MainWorker {
       ),
       deno_webstorage::init(options.location_data_dir.clone()),
       deno_crypto::init(options.seed),
+      deno_broadcast_channel::init(),
       deno_webgpu::init(options.unstable),
       deno_timers::init::<Permissions>(),
       // Metrics