diff --git a/Gemfile b/Gemfile
index 85071c6eb..2d95468ba 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,22 +4,36 @@ source 'https://rubygems.org'
 
 git_source(:github) { |repo_name| "https://github.com/#{repo_name}" }
 
-gem 'badge'
-gem 'cocoapods'
-gem 'danger'
-gem 'danger-commit_lint'
-gem 'fastlane'
-gem 'fastlane-plugin-lizard'
+gem 'danger', group: :danger_dependencies
+gem 'fastlane', group: :fastlane_dependencies
 gem 'jazzy'
 gem 'json'
-gem 'plist'
-gem 'rubocop', '1.38'
-gem 'rubocop-performance'
-gem 'rubocop-require_tools'
-gem 'sinatra'
+gem 'rubocop', '1.38', group: :rubocop_dependencies
+gem 'sinatra', group: :sinatra_dependencies
 gem 'slather'
-gem 'xcode-install'
-gem 'xctest_list'
 
 plugins_path = File.join(File.dirname(__FILE__), 'fastlane', 'Pluginfile')
 eval_gemfile(plugins_path) if File.exist?(plugins_path)
+
+group :fastlane_dependencies do
+  gem 'badge'
+  gem 'cocoapods'
+  gem 'fastlane-plugin-lizard'
+  gem 'plist'
+  gem 'xcode-install'
+  gem 'xctest_list'
+end
+
+group :sinatra_dependencies do
+  gem 'puma'
+  gem 'rackup'
+end
+
+group :rubocop_dependencies do
+  gem 'rubocop-performance'
+  gem 'rubocop-require_tools'
+end
+
+group :danger_dependencies do
+  gem 'danger-commit_lint'
+end
diff --git a/Gemfile.lock b/Gemfile.lock
index 858bd2324..2749c2d2c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -288,6 +288,7 @@ GEM
     nap (1.1.0)
     naturally (2.2.1)
     netrc (0.11.0)
+    nio4r (2.7.0)
     no_proxy_fix (0.1.2)
     nokogiri (1.16.0)
       mini_portile2 (~> 2.8.2)
@@ -307,6 +308,8 @@ GEM
       coderay (~> 1.1)
       method_source (~> 1.0)
     public_suffix (4.0.7)
+    puma (6.4.2)
+      nio4r (~> 2.0)
     racc (1.7.3)
     rack (3.0.8)
     rack-protection (4.0.0)
@@ -314,6 +317,9 @@ GEM
       rack (>= 3.0.0, < 4)
     rack-session (2.0.0)
       rack (>= 3.0.0)
+    rackup (2.1.0)
+      rack (>= 3)
+      webrick (~> 1.8)
     rainbow (3.1.1)
     rake (13.1.0)
     rchardet (1.8.0)
@@ -390,6 +396,7 @@ GEM
       concurrent-ruby (~> 1.0)
     uber (0.1.0)
     unicode-display_width (2.5.0)
+    webrick (1.8.1)
     word_wrap (1.0.0)
     xcinvoke (0.3.0)
       liferaft (~> 0.0.6)
@@ -425,6 +432,8 @@ DEPENDENCIES
   jazzy
   json
   plist
+  puma
+  rackup
   rubocop (= 1.38)
   rubocop-performance
   rubocop-require_tools
diff --git a/TestTools/Robots/Sinatra.swift b/TestTools/Robots/Sinatra.swift
index 1ef97d5ba..e3049fd6d 100644
--- a/TestTools/Robots/Sinatra.swift
+++ b/TestTools/Robots/Sinatra.swift
@@ -27,6 +27,7 @@ public class Sinatra {
     private func invokeSinatra(url: URL, body: [String: Any] = [:]) {
         var request = URLRequest(url: url)
         request.httpMethod = "POST"
+        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
         request.httpBody = try? JSONSerialization.data(withJSONObject: body, options: [])
         URLSession.shared.dataTask(with: request).resume()
     }