diff --git a/Gemfile b/Gemfile
index bb944a6b1..638506882 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,6 +13,7 @@ gem 'pg', '~> 1.4'
 gem 'json_translate', '~> 4.0.0'
 gem 'devise', '~> 4.9.1'
 gem 'devise-i18n', '~> 1.11.0'
+gem 'invisible_captcha', '~> 2.3.0'
 gem 'http_accept_language', '~> 2.1.1'
 gem 'kaminari', '~> 1.2.1'
 gem 'simple_form', '~> 5.0.2'
diff --git a/Gemfile.lock b/Gemfile.lock
index dfe6a6612..c36831f54 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -183,6 +183,8 @@ GEM
       has_scope (>= 0.6)
       railties (>= 6.0)
       responders (>= 2)
+    invisible_captcha (2.3.0)
+      rails (>= 5.2)
     jmespath (1.6.2)
     jquery-rails (4.4.0)
       rails-dom-testing (>= 1, < 3)
@@ -450,6 +452,7 @@ DEPENDENCIES
   has_scope (~> 0.7.2)
   http_accept_language (~> 2.1.1)
   image_processing (~> 1.12)
+  invisible_captcha (~> 2.3.0)
   jquery-rails (~> 4.4.0)
   json_translate (~> 4.0.0)
   kaminari (~> 1.2.1)
diff --git a/README.md b/README.md
index ea489cd52..8cc6d8fb0 100644
--- a/README.md
+++ b/README.md
@@ -15,8 +15,7 @@ of it and is prepared to be able to accommodate several Time Banks in a single i
 for this account with three levels of privileges: superadmin, admin (only manages a bank)
 and members of a bank.
 
-![Users list](docs/images/usuarios.png)
-![Offers list](docs/images/ofertas.png)
+![Demo UI](docs/images/demo_ui.jpeg)
 
 TimeOverflow is divided into 2 large blocks:
 
diff --git a/app/admin/user.rb b/app/admin/user.rb
index fe8ec828c..dc0de5e09 100644
--- a/app/admin/user.rb
+++ b/app/admin/user.rb
@@ -1,4 +1,6 @@
 ActiveAdmin.register User do
+  config.batch_actions = true
+
   action_item :upload_csv, only: :index do
     link_to I18n.t("active_admin.users.upload_from_csv"), action: "upload_csv"
   end
@@ -15,6 +17,7 @@
   end
 
   index do
+    selectable_column
     column do |user|
       link_to image_tag(avatar_url(user, 24)), admin_user_path(user)
     end
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 689adef37..1f83741fe 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -3,6 +3,8 @@ class UsersController < ApplicationController
   before_action :user_should_be_confirmed, except: %i[signup create please_confirm]
   before_action :member_should_exist_and_be_active, except: %i[signup create edit show update please_confirm]
 
+  invisible_captcha only: :create, if: -> { params[:from_signup].present? }
+
   has_scope :tagged_with, as: :tag
 
   def index
diff --git a/app/jobs/organization_notifier_job.rb b/app/jobs/organization_notifier_job.rb
index e8949bba6..e8d7ec650 100644
--- a/app/jobs/organization_notifier_job.rb
+++ b/app/jobs/organization_notifier_job.rb
@@ -1,7 +1,7 @@
 # A weekly digest email.
 #
 # Strategy: go throught all organizations and take latest active posts from last week
-# posted by active members. Send an email to all active and online members
+# posted by active members. Send an email to all confirmed, active and online members
 # with the email notifications enabled with those posts. Group emails by user's locale.
 
 # Schedule defined in config/schedule.yml file.
@@ -24,11 +24,11 @@ def perform
   private
 
   def users_by_locale(organization)
-    with_notifications = organization.users.online_active.actives.notifications
-    org_locales = with_notifications.pluck(:locale).uniq
+    org_users = organization.users.online_active.actives.confirmed.notifications
+    org_locales = org_users.pluck(:locale).uniq
 
     org_locales.each_with_object({}) do |locale, hash|
-      hash[locale] = with_notifications.where(locale: locale)
+      hash[locale] = org_users.where(locale: locale)
     end
   end
 end
diff --git a/app/mailers/organization_notifier.rb b/app/mailers/organization_notifier.rb
index 761ebaf34..5827711f5 100644
--- a/app/mailers/organization_notifier.rb
+++ b/app/mailers/organization_notifier.rb
@@ -2,7 +2,6 @@ class OrganizationNotifier < ActionMailer::Base
   default from: "\"TimeOverflow\" <info@timeoverflow.org>"
 
   def recent_posts(posts, locale, users)
-    # last 10 posts of offers and inquiries
     @offers = posts.where(type: "Offer").take(10)
     @inquiries = posts.where(type: "Inquiry").take(10)
 
diff --git a/app/models/user.rb b/app/models/user.rb
index 49f462f19..2877fb8e2 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -41,6 +41,7 @@ class User < ApplicationRecord
   scope :actives, -> { joins(:members).where(members: { active: true }) }
   scope :online_active, -> { where("sign_in_count > 0") }
   scope :notifications, -> { where(notifications: true) }
+  scope :confirmed, -> { where.not(confirmed_at: nil) }
 
   validates :username, presence: true
   validates :email, presence: true, uniqueness: true
diff --git a/app/views/users/_form.html.erb b/app/views/users/_form.html.erb
index 56118ff56..02a25a05b 100644
--- a/app/views/users/_form.html.erb
+++ b/app/views/users/_form.html.erb
@@ -1,6 +1,7 @@
 <%= show_error_messages!(@user) %>
 <%= simple_form_for @user do |f| %>
   <%= f.hidden_field :locale, value: I18n.locale %>
+  <%= invisible_captcha %>
 
   <div class="form-inputs">
     <%= f.input :username %>
diff --git a/config/initializers/active_admin.rb b/config/initializers/active_admin.rb
index 135f86fa6..7cfbf91f4 100644
--- a/config/initializers/active_admin.rb
+++ b/config/initializers/active_admin.rb
@@ -7,7 +7,6 @@
   config.current_user_method = :current_user
   config.logout_link_path = :destroy_user_session_path
   config.logout_link_method = :delete
-  config.batch_actions = false
   config.comments = false
   config.namespace :admin do |admin|
     admin.build_menu :utility_navigation do |menu|
diff --git a/config/initializers/invisible_captcha.rb b/config/initializers/invisible_captcha.rb
new file mode 100644
index 000000000..30eeb9efc
--- /dev/null
+++ b/config/initializers/invisible_captcha.rb
@@ -0,0 +1,4 @@
+InvisibleCaptcha.setup do |config|
+  config.timestamp_enabled = !Rails.env.test?
+  config.spinner_enabled = !Rails.env.test?
+end
diff --git a/docs/images/demo_ui.jpeg b/docs/images/demo_ui.jpeg
new file mode 100644
index 000000000..4e07880b0
Binary files /dev/null and b/docs/images/demo_ui.jpeg differ
diff --git a/docs/images/ofertas.png b/docs/images/ofertas.png
deleted file mode 100644
index ce64f5afa..000000000
Binary files a/docs/images/ofertas.png and /dev/null differ
diff --git a/docs/images/usuarios.png b/docs/images/usuarios.png
deleted file mode 100644
index 0b8b82e2d..000000000
Binary files a/docs/images/usuarios.png and /dev/null differ
diff --git a/spec/controllers/users_controller_spec.rb b/spec/controllers/users_controller_spec.rb
index b715a4f9a..ce5d6f76c 100644
--- a/spec/controllers/users_controller_spec.rb
+++ b/spec/controllers/users_controller_spec.rb
@@ -441,8 +441,8 @@
 
       let(:uploaded_file) do
         Rack::Test::UploadedFile.new(
-          Rails.root.join("docs/images/ofertas.png"),
-          "image/png"
+          Rails.root.join("docs/images/demo_ui.jpeg"),
+          "image/jpeg"
         )
       end
 
diff --git a/spec/mailers/organization_notifier_spec.rb b/spec/mailers/organization_notifier_spec.rb
index 039c0266f..89b85bd03 100644
--- a/spec/mailers/organization_notifier_spec.rb
+++ b/spec/mailers/organization_notifier_spec.rb
@@ -2,7 +2,7 @@
   let(:test_organization) { Fabricate(:organization) }
   let!(:offer) { Fabricate(:offer, organization: test_organization) }
   let!(:inquiry) { Fabricate(:inquiry, organization: test_organization) }
-  let(:user) { Fabricate(:user, email: "user@example.com", locale: :en) }
+  let(:user) { Fabricate(:user, email: "user@timeoverflow.org", locale: :en) }
   let(:member) { Fabricate(:member, organization: test_organization, user: user) }
 
   describe "send an email" do
@@ -17,7 +17,7 @@
     let(:mail) { OrganizationNotifier.recent_posts(test_organization.posts, :en, [user]) }
 
     it "receive email only active and online users" do
-      expect(mail.bcc).to eql(["user@example.com"])
+      expect(mail.bcc).to eql(["user@timeoverflow.org"])
     end
     it "to should be null" do
       expect(mail.to).to be_nil