diff --git a/twenty-cli/lib/twenty-cli/command/down.rb b/twenty-cli/lib/twenty-cli/command/down.rb
index 0695593..33c992c 100644
--- a/twenty-cli/lib/twenty-cli/command/down.rb
+++ b/twenty-cli/lib/twenty-cli/command/down.rb
@@ -3,6 +3,7 @@
 class Twenty::Command::Down < Twenty::Command
   set_banner usage: "twenty down [OPTIONS]",
              description: "Stop the twenty web server"
+  include Twenty::Path
   prepend Twenty::Command::SQLiteMixin
 
   def run
@@ -13,6 +14,19 @@ class Twenty::Command::Down < Twenty::Command
   private
 
   def run_command(options)
-    warn "[twenty] down..."
+    if File.readable?(pidfile)
+      Process.kill('SIGINT', Integer(pid))
+    else
+      warn "PID file is not readable."
+    end
+  rescue Errno::ESRCH
+    warn "No such process."
+    FileUtils.rm(pidfile)
+  end
+
+  def pid
+    @pid ||= File
+               .binread(pidfile)
+               .gsub(/[^\d]/, '')
   end
 end
diff --git a/twenty-cli/lib/twenty-cli/command/up.rb b/twenty-cli/lib/twenty-cli/command/up.rb
index eb68498..1e7f259 100644
--- a/twenty-cli/lib/twenty-cli/command/up.rb
+++ b/twenty-cli/lib/twenty-cli/command/up.rb
@@ -12,6 +12,10 @@ class Twenty::Command::Up < Twenty::Command
              "Listen on PORT (default: 2020)",
              default: 2020,
              as: Integer
+  set_option "-b",
+             "--background",
+             "Run the web server in the background",
+             default: false
 
   include CommonOptionMixin
   prepend Twenty::Command::MigrationMixin
@@ -26,7 +30,8 @@ class Twenty::Command::Up < Twenty::Command
 
   def run_command(options)
     server = Twenty::Servlet.server(options)
-    trap(:SIGINT) { server.shutdown }
-    server.start
+    options.background ? server.start! : server.start
+  rescue Interrupt
+    server.shutdown
   end
 end
diff --git a/twenty-server/lib/twenty-server.rb b/twenty-server/lib/twenty-server.rb
index f98016b..1527a7e 100644
--- a/twenty-server/lib/twenty-server.rb
+++ b/twenty-server/lib/twenty-server.rb
@@ -4,24 +4,19 @@ module Twenty
   require "fileutils"
   require "webrick"
   require "active_record"
+  require_relative "twenty-server/path"
   require_relative "twenty-server/graphql"
   require_relative "twenty-server/servlet"
   require_relative "twenty-server/migration"
   require_relative "twenty-server/model"
   extend FileUtils
-
-  ##
-  # @return [String]
-  #  Returns the directory where twenty stores data.
-  def self.data_dir
-    File.join(Dir.home, ".local", "share", "20")
-  end
+  extend Path
 
   ##
   # @return [String]
   #  Returns the location of the default SQLite database.
   def self.default_database
-    @default_database ||= File.join(data_dir, "database.sqlite")
+    @default_database ||= File.join(datadir, "database.sqlite")
   end
 
   ##
@@ -44,8 +39,8 @@ module Twenty
   # @return [void]
   # @api private
   def self.prepare_dir
-    return if File.exist?(default_database)
-    mkdir_p(data_dir)
+    mkdir_p(datadir)
+    mkdir_p(tmpdir)
     touch(default_database)
   rescue => ex
     warn "prepare_dir error: #{ex.message} (#{ex.class})"
diff --git a/twenty-server/lib/twenty-server/path.rb b/twenty-server/lib/twenty-server/path.rb
new file mode 100644
index 0000000..5dda964
--- /dev/null
+++ b/twenty-server/lib/twenty-server/path.rb
@@ -0,0 +1,23 @@
+module Twenty::Path
+  ##
+  # @return [String]
+  #  Returns the directory where twenty stores persistent data.
+  def datadir
+    File.join(Dir.home, ".local", "share", "20")
+  end
+
+  ##
+  # @return [String]
+  #  Returns the directory where twenty stores temporary data.
+  def tmpdir
+    File.join(Dir.tmpdir, "20")
+  end
+
+  ##
+  # @return [String]
+  #  Returns the file where twenty can write the PID of
+  #  a web server running in the background.
+  def pidfile
+    File.join(tmpdir, "server.pid")
+  end
+end
diff --git a/twenty-server/lib/twenty-server/servlet/mixin/server_mixin.rb b/twenty-server/lib/twenty-server/servlet/mixin/server_mixin.rb
index 25683d0..8462056 100644
--- a/twenty-server/lib/twenty-server/servlet/mixin/server_mixin.rb
+++ b/twenty-server/lib/twenty-server/servlet/mixin/server_mixin.rb
@@ -1,6 +1,24 @@
 # frozen_string_literal: true
 
 module Twenty::Servlet::ServerMixin
+  ##
+  # This module extends an instance of WEBrick::HTTPServer
+  # with daemon support.
+  module Daemon
+    include Twenty::Path
+
+    ##
+    # Starts a webrick server in the background.
+    # @return [void]
+    def start!
+      Process.daemon
+      File.binwrite(pidfile, Process.pid.to_s)
+      start
+    ensure
+      FileUtils.rm(pidfile)
+    end
+  end
+
   ##
   # @param [Hash] cli_options
   #  CLI options merged into
@@ -11,7 +29,7 @@ module Twenty::Servlet::ServerMixin
   def server(cli_options = {})
     server = WEBrick::HTTPServer.new server_options(cli_options)
     server.mount "/graphql", Twenty::Servlet::GraphQL
-    server
+    server.extend(Daemon)
   end
 
   ##