diff --git a/Gemfile b/Gemfile
index 1a43ca93..04a12d43 100644
--- a/Gemfile
+++ b/Gemfile
@@ -20,7 +20,7 @@ gem 'puma', '~> 3.0'
 gem 'responders', '~> 2.0'
 
 # as supported databases
-# gem 'mysql2'
+gem 'mysql2'
 gem 'pg'
 
 # for tracking data changes
@@ -41,9 +41,9 @@ gem 'devise_ichain_authenticatable'
 gem 'omniauth'
 gem 'omniauth-google-oauth2'
 gem 'omniauth-discourse'
-# gem 'omniauth-openid'
-# gem 'omniauth-facebook'
-# gem 'omniauth-github'
+gem 'omniauth-openid'
+gem 'omniauth-facebook'
+gem 'omniauth-github'
 
 # Bot-filtering
 gem 'recaptcha', require: 'recaptcha/rails'
diff --git a/Gemfile.lock b/Gemfile.lock
index 788c1861..7125136f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -304,6 +304,7 @@ GEM
     multi_json (1.13.1)
     multi_xml (0.6.0)
     multipart-post (2.1.1)
+    mysql2 (0.5.3)
     nenv (0.3.0)
     net-http-persistent (3.0.1)
       connection_pool (~> 2.2)
@@ -325,6 +326,11 @@ GEM
       rack (>= 1.6.2, < 3)
     omniauth-discourse (1.0.0)
       omniauth (~> 1.0)
+    omniauth-facebook (6.0.0)
+      omniauth-oauth2 (~> 1.2)
+    omniauth-github (1.3.0)
+      omniauth (~> 1.5)
+      omniauth-oauth2 (>= 1.4.0, < 2.0)
     omniauth-google-oauth2 (0.6.1)
       jwt (>= 2.0)
       omniauth (>= 1.1.1)
@@ -332,6 +338,9 @@ GEM
     omniauth-oauth2 (1.6.0)
       oauth2 (~> 1.1)
       omniauth (~> 1.9)
+    omniauth-openid (1.0.1)
+      omniauth (~> 1.0)
+      rack-openid (~> 1.3.1)
     open4 (1.3.4)
     orm_adapter (0.5.0)
     paper_trail (10.3.1)
@@ -373,6 +382,9 @@ GEM
     public_suffix (3.1.1)
     puma (3.12.2)
     rack (2.0.8)
+    rack-openid (1.3.1)
+      rack (>= 1.1.0)
+      ruby-openid (>= 2.1.8)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
     rails (5.2.3)
@@ -489,6 +501,7 @@ GEM
     rubocop-rspec (1.36.0)
       rubocop (>= 0.68.1)
     ruby-oembed (0.12.0)
+    ruby-openid (2.9.2)
     ruby-progressbar (1.10.1)
     ruby-rc4 (0.1.5)
     ruby_dep (1.5.0)
@@ -654,10 +667,14 @@ DEPENDENCIES
   mina
   mini_magick
   money-rails
+  mysql2
   nokogiri (>= 1.8.1)
   omniauth
   omniauth-discourse
+  omniauth-facebook
+  omniauth-github
   omniauth-google-oauth2
+  omniauth-openid
   paper_trail
   pdf-inspector
   pg