diff --git a/Gemfile b/Gemfile
index ead69aa..cb91e69 100644
--- a/Gemfile
+++ b/Gemfile
@@ -21,6 +21,7 @@ gem 'rack-cors'
 gem 'react-rails'
 gem 'rubytree'
 gem 'acts_as_tenant'
+gem 'httparty'
 
 group :development, :test do
   gem 'annotaterb'
diff --git a/Gemfile.lock b/Gemfile.lock
index 7e795fc..c0660de 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -126,6 +126,10 @@ GEM
       raabro (~> 1.4)
     globalid (1.2.1)
       activesupport (>= 6.1)
+    httparty (0.22.0)
+      csv
+      mini_mime (>= 1.0.0)
+      multi_xml (>= 0.5.2)
     i18n (1.14.6)
       concurrent-ruby (~> 1.0)
     importmap-rails (2.0.3)
@@ -188,6 +192,8 @@ GEM
     money (6.19.0)
       i18n (>= 0.6.4, <= 2)
     msgpack (1.7.2)
+    multi_xml (0.7.1)
+      bigdecimal (~> 3.1)
     net-imap (0.5.1)
       date
       net-protocol
@@ -398,6 +404,7 @@ DEPENDENCIES
   devise (~> 4.9)
   factory_bot_rails
   faker
+  httparty
   importmap-rails
   jbuilder
   jsonapi-rails
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index f163c3e..15a4b17 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -30,6 +30,18 @@ class ApplicationController < ActionController::Base
 
   private
 
+  def validate_captcha!
+    Rails.logger.info("Captcha params: #{captcha_params}")
+
+    return if LibreCaptcha.new.valid?(id: captcha_params[:id], answer: captcha_params[:answer])
+
+    render json: { error: 'Incorrect CAPTCHA solution' }, status: :unprocessable_entity
+  end
+
+  def captcha_params
+    params.expect(captcha: [:id, :answer])
+  end
+  
   def default_url_options(options = {})
     options.merge(path_params: { slug: ActsAsTenant.current_tenant&.slug })
   end
diff --git a/app/controllers/captcha_controller.rb b/app/controllers/captcha_controller.rb
new file mode 100644
index 0000000..428328d
--- /dev/null
+++ b/app/controllers/captcha_controller.rb
@@ -0,0 +1,13 @@
+# Copyright (C) 2024 Manuel Bustillo
+
+class CaptchaController < ApplicationController
+  skip_before_action :authenticate_user!
+
+  def create
+    id = LibreCaptcha.new.get_id
+    render json: {
+      id:,
+      media_url: media_captcha_index_url(id:)
+    }, status: :created
+  end
+end
diff --git a/app/controllers/users/registrations_controller.rb b/app/controllers/users/registrations_controller.rb
index 24d8eca..4894d4b 100644
--- a/app/controllers/users/registrations_controller.rb
+++ b/app/controllers/users/registrations_controller.rb
@@ -4,6 +4,8 @@ class Users::RegistrationsController < Devise::RegistrationsController
   clear_respond_to 
   respond_to :json
 
+  before_action :validate_captcha!, only: :create
+
   def create
     wedding = Wedding.create(wedding_params)
     unless wedding.persisted?
diff --git a/app/services/libre_captcha.rb b/app/services/libre_captcha.rb
new file mode 100644
index 0000000..8684e9f
--- /dev/null
+++ b/app/services/libre_captcha.rb
@@ -0,0 +1,20 @@
+# Copyright (C) 2024 Manuel Bustillo
+
+class LibreCaptcha
+  def get_id
+    HTTParty.post("http://libre-captcha:8888/v2/captcha", 
+      body: {
+        input_type: "text",
+        level: :hard,
+        media: 'image/png',
+        size: '350x100'
+      }.to_json
+    ).then { |raw| JSON.parse(raw)['id'] }
+  end
+
+  def valid?(id:, answer:)
+    HTTParty.post("http://libre-captcha:8888/v2/answer",
+      body: { id:, answer: }.to_json
+    ).then { |raw| JSON.parse(raw)['result'] == 'True' }
+  end
+end
\ No newline at end of file
diff --git a/config/routes.rb b/config/routes.rb
index 10810fe..1357d9c 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -23,6 +23,9 @@ Rails.application.routes.draw do
     resources :tables_arrangements, only: %i[index show]
   end
 
+  resources :captcha, only: :create do
+    get 'v2/media', to: 'captcha#media', on: :collection, as: :media
+  end
 
   mount Rswag::Ui::Engine => '/api-docs'
   mount Rswag::Api::Engine => '/api-docs'
diff --git a/docker-compose.yml b/docker-compose.yml
index e1a5977..64b54c7 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -36,6 +36,12 @@ services:
       - backend
     volumes:
       - ../wedding-planner-frontend/:/app
+  libre-captcha:
+    image: librecaptcha/lc-core:latest
+    volumes: 
+      - "./tmp/libre-captcha-data:/lc-core/data"
+    ports: 
+      - 8888
   nginx:
     image: nginx:latest
     ports:
diff --git a/nginx.conf b/nginx.conf
index 06d059b..58c2bb9 100644
--- a/nginx.conf
+++ b/nginx.conf
@@ -12,6 +12,11 @@ server {
         proxy_set_header Host $http_host;
     }
 
+    location /captcha/v2/media/ {
+        proxy_pass http://libre-captcha:8888/v2/media/;
+        proxy_set_header Host $http_host;
+    }
+
     location / {
         proxy_pass http://frontend:3000;
         proxy_set_header Host $http_host;
diff --git a/spec/requests/captcha_spec.rb b/spec/requests/captcha_spec.rb
new file mode 100644
index 0000000..607a2d9
--- /dev/null
+++ b/spec/requests/captcha_spec.rb
@@ -0,0 +1,24 @@
+# Copyright (C) 2024 Manuel Bustillo
+
+require 'swagger_helper'
+
+RSpec.describe 'captcha', type: :request do
+  path '/captcha' do
+
+    post('create a CAPTCHA challenge') do
+      tags 'CAPTCHA'
+      consumes 'application/json'
+      produces 'application/json'
+      
+      response(201, 'created') do
+        schema type: :object,
+        required: %i[id], 
+        properties: {
+          id: { type: :string, format: :uuid },
+          media_url: { type: :string, format: :uri },
+        }
+        xit
+      end
+    end
+  end
+end
diff --git a/spec/requests/schemas.rb b/spec/requests/schemas.rb
index 6602db8..e1f7b43 100644
--- a/spec/requests/schemas.rb
+++ b/spec/requests/schemas.rb
@@ -18,5 +18,16 @@ module Swagger
       example: :default,
       description: 'Wedding slug'
     }
+
+    CAPTCHA = {
+      captcha: {
+        type: :object,
+        required: %i[id answer],
+        properties: {
+          id: { type: :string, format: :uuid },
+          answer: { type: :string }
+        }
+      }
+    } 
   end
 end
\ No newline at end of file
diff --git a/spec/requests/users/registrations_spec.rb b/spec/requests/users/registrations_spec.rb
index ae0f86d..f29b387 100644
--- a/spec/requests/users/registrations_spec.rb
+++ b/spec/requests/users/registrations_spec.rb
@@ -30,7 +30,8 @@ RSpec.describe 'users/registrations', type: :request do
             properties: {
               date: { type: :string, format: :date},
             }
-          }
+          },
+          **Swagger::Schema::CAPTCHA
         }
       }