diff --git a/CHANGELOG.md b/CHANGELOG.md
index cb1c5263..713cbb00 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,8 @@ a block with this page, after which the page is closed.
 - Windows support
 - Show warning and accept dialog if no handler given
 - `Ferrum::Cookies#set` ability to set cookie using `Ferrum::Cookies::Cookie` object
+- `Ferrum::Network#emulate_network_conditions` activates emulation of network conditions
+- `Ferrum::Network#offline_mode` puts browser into offline mode
 
 ### Changed
 
diff --git a/README.md b/README.md
index f1a3d378..ee7ab7d6 100644
--- a/README.md
+++ b/README.md
@@ -561,13 +561,41 @@ end
 browser.network.authorize(user: "login", password: "pass", type: :proxy)
 
 browser.go_to("https://google.com")
-
 ```
 
 You used to call `authorize` method without block, but since it's implemented using request interception there could be
 a collision with another part of your code that also uses request interception, so that authorize allows the request
 while your code denies but it's too late. The block is mandatory now.
 
+#### emulate_network_conditions(\*\*options)
+
+Activates emulation of network conditions.
+
+* options `Hash`
+  * :offline `Boolean` emulate internet disconnection, `false` by default
+  * :latency `Integer` minimum latency from request sent to response headers received (ms), `0` by
+    default
+  * :download_throughput `Integer` maximal aggregated download throughput (bytes/sec), `-1`
+    by default, disables download throttling
+  * :upload_throughput `Integer` maximal aggregated upload throughput (bytes/sec), `-1`
+    by default, disables download throttling
+  * :connection_type `String` connection type if known, one of: none, cellular2g, cellular3g, cellular4g,
+    bluetooth, ethernet, wifi, wimax, other. `nil` by default
+
+```ruby
+browser.network.emulate_network_conditions(connection_type: "cellular2g")
+browser.go_to("https://github.com/")
+```
+
+#### offline_mode
+
+Activates offline mode for a page.
+
+```ruby
+browser.network.offline_mode
+browser.go_to("https://github.com/") # => Ferrum::StatusError (Request to https://github.com/ failed to reach server, check DNS and server status)
+```
+
 
 ## Proxy
 
diff --git a/lib/ferrum/browser.rb b/lib/ferrum/browser.rb
index 8926195f..ec266a81 100644
--- a/lib/ferrum/browser.rb
+++ b/lib/ferrum/browser.rb
@@ -67,7 +67,7 @@ def initialize(options = nil)
 
       self.base_url = @options[:base_url] if @options.key?(:base_url)
 
-      if ENV["FERRUM_DEBUG"] && !@logger
+      if ENV.fetch("FERRUM_DEBUG", nil) && !@logger
         $stdout.sync = true
         @logger = $stdout
         @options[:logger] = @logger
diff --git a/lib/ferrum/browser/command.rb b/lib/ferrum/browser/command.rb
index f8613a69..187e1c8c 100644
--- a/lib/ferrum/browser/command.rb
+++ b/lib/ferrum/browser/command.rb
@@ -29,7 +29,7 @@ def initialize(defaults, options, user_data_dir)
         @defaults = defaults
         @options = options
         @user_data_dir = user_data_dir
-        @path = options[:browser_path] || ENV["BROWSER_PATH"] || defaults.detect_path
+        @path = options[:browser_path] || ENV.fetch("BROWSER_PATH", nil) || defaults.detect_path
         raise Cliver::Dependency::NotFound, NOT_FOUND unless @path
 
         merge_options
diff --git a/lib/ferrum/network.rb b/lib/ferrum/network.rb
index 1722be94..63f7f941 100644
--- a/lib/ferrum/network.rb
+++ b/lib/ferrum/network.rb
@@ -17,6 +17,7 @@ class Network
     AUTHORIZE_BLOCK_MISSING = "Block is missing, call `authorize(...) { |r| r.continue } "\
                               "or subscribe to `on(:request)` events before calling it"
     AUTHORIZE_TYPE_WRONG = ":type should be in #{AUTHORIZE_TYPE}"
+    ALLOWED_CONNECTION_TYPE = %w[none cellular2g cellular3g cellular4g bluetooth ethernet wifi wimax other].freeze
 
     attr_reader :traffic
 
@@ -150,6 +151,25 @@ def build_exchange(id)
       Network::Exchange.new(@page, id).tap { |e| @traffic << e }
     end
 
+    def emulate_network_conditions(offline: false, latency: 0,
+                                   download_throughput: -1, upload_throughput: -1,
+                                   connection_type: nil)
+      params = {
+        offline: offline, latency: latency,
+        downloadThroughput: download_throughput,
+        uploadThroughput: upload_throughput
+      }
+
+      params[:connectionType] = connection_type if connection_type && ALLOWED_CONNECTION_TYPE.include?(connection_type)
+
+      @page.command("Network.emulateNetworkConditions", **params)
+      true
+    end
+
+    def offline_mode
+      emulate_network_conditions(offline: true, latency: 0, download_throughput: 0, upload_throughput: 0)
+    end
+
     private
 
     def subscribe_request_will_be_sent
diff --git a/spec/browser_spec.rb b/spec/browser_spec.rb
index 7bc6672e..ca3e4826 100644
--- a/spec/browser_spec.rb
+++ b/spec/browser_spec.rb
@@ -369,11 +369,11 @@ module Ferrum
     it "allows the driver to have a custom host", skip: ENV["BROWSER_TEST_HOST"].nil? do
       # Use custom host "pointing" to localhost in /etc/hosts or iptables for this.
       # https://superuser.com/questions/516208/how-to-change-ip-address-to-point-to-localhost
-      browser = Browser.new(host: ENV["BROWSER_TEST_HOST"], port: 12_345)
+      browser = Browser.new(host: ENV.fetch("BROWSER_TEST_HOST"), port: 12_345)
       browser.go_to(base_url)
 
       expect do
-        TCPServer.new(ENV["BROWSER_TEST_HOST"], 12_345)
+        TCPServer.new(ENV.fetch("BROWSER_TEST_HOST"), 12_345)
       end.to raise_error(Errno::EADDRINUSE)
     ensure
       browser&.quit
diff --git a/spec/network_spec.rb b/spec/network_spec.rb
index 16c29cd4..30fe7183 100644
--- a/spec/network_spec.rb
+++ b/spec/network_spec.rb
@@ -393,5 +393,25 @@ module Ferrum
         expect(page.body).to include("Authorized POST request")
       end
     end
+
+    it "#emulate_network_conditions", skip: "doesn't work for now" do
+      page.network.emulate_network_conditions(latency: 500)
+
+      start = Utils::ElapsedTime.monotonic_time
+      page.go_to("/ferrum/with_js")
+
+      expect(Utils::ElapsedTime.elapsed_time(start)).to eq(2000)
+    end
+
+    it "#offline_mode" do
+      page.network.offline_mode
+
+      expect { page.go_to("/ferrum/with_js") }.to raise_error(
+        Ferrum::StatusError,
+        %r{Request to http://.*/ferrum/with_js failed to reach server, check DNS and server status}
+      )
+
+      expect(page.body).to eq("<html><head></head><body></body></html>")
+    end
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 2f9dad2b..4e2260e6 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -30,6 +30,7 @@
     base_url = Ferrum::Server.server.base_url
     options = { base_url: base_url }
     options.merge!(headless: false) if ENV["HEADLESS"] == "false"
+    options.merge!(slowmo: ENV["SLOWMO"].to_f) if ENV["SLOWMO"].to_f > 0
 
     if ENV["CI"]
       ferrum_logger = StringIO.new
@@ -53,7 +54,7 @@
   end
 
   config.after(:each) do |example|
-    save_exception_artifacts(browser, example.metadata, ferrum_logger) if ENV["CI"] && example.exception
+    save_exception_artifacts(browser, example.metadata, ferrum_logger) if ENV.fetch("CI", nil) && example.exception
 
     reset
   end