diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index c292590..999f4bc 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -4,13 +4,13 @@ on:
   push:
     branches:
       - main
-
   pull_request:
 
 jobs:
   build:
     runs-on: ubuntu-latest
     name: Ruby ${{ matrix.ruby }}
+
     strategy:
       matrix:
         ruby:
@@ -20,10 +20,21 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
+
+      # 👇 ESTE STEP FALTABA
+      - name: Install system dependencies (GD)
+        run: |
+          sudo apt update
+          sudo apt install -y \
+            libgd-dev \
+            pkg-config \
+            build-essential
+
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
           bundler-cache: true
+
       - name: Run the default task
         run: bundle exec rake
diff --git a/Gemfile b/Gemfile
index 5689813..1838841 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,6 +6,7 @@ source "https://rubygems.org"
 gemspec
 
 gem "irb"
+gem "pry"
 gem "rake", "~> 13.0"
 
 gem "rspec", "~> 3.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index a4a09df..d93ace1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,11 +2,13 @@ PATH
   remote: .
   specs:
     imprint (0.1.0)
+      ruby-libgd
 
 GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.3)
+    coderay (1.1.3)
     date (3.5.1)
     diff-lcs (1.6.2)
     erb (6.0.1)
@@ -18,6 +20,7 @@ GEM
     json (2.18.0)
     language_server-protocol (3.17.0.5)
     lint_roller (1.1.0)
+    method_source (1.1.0)
     parallel (1.27.0)
     parser (3.3.10.1)
       ast (~> 2.4.1)
@@ -26,6 +29,10 @@ GEM
       prettyprint
     prettyprint (0.2.0)
     prism (1.8.0)
+    pry (0.16.0)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+      reline (>= 0.6.0)
     psych (5.3.1)
       date
       stringio
@@ -66,6 +73,7 @@ GEM
     rubocop-ast (1.49.0)
       parser (>= 3.3.7.2)
       prism (~> 1.7)
+    ruby-libgd (0.2.3)
     ruby-progressbar (1.13.0)
     stringio (3.2.0)
     tsort (0.2.0)
@@ -80,12 +88,14 @@ PLATFORMS
 DEPENDENCIES
   imprint!
   irb
+  pry
   rake (~> 13.0)
   rspec (~> 3.0)
   rubocop (~> 1.21)
 
 CHECKSUMS
   ast (2.4.3) sha256=954615157c1d6a382bc27d690d973195e79db7f55e9765ac7c481c60bdb4d383
+  coderay (1.1.3) sha256=dc530018a4684512f8f38143cd2a096c9f02a1fc2459edcfe534787a7fc77d4b
   date (3.5.1) sha256=750d06384d7b9c15d562c76291407d89e368dda4d4fff957eb94962d325a0dc0
   diff-lcs (1.6.2) sha256=9ae0d2cba7d4df3075fe8cd8602a8604993efc0dfa934cff568969efb1909962
   erb (6.0.1) sha256=28ecdd99c5472aebd5674d6061e3c6b0a45c049578b071e5a52c2a7f13c197e5
@@ -95,11 +105,13 @@ CHECKSUMS
   json (2.18.0) sha256=b10506aee4183f5cf49e0efc48073d7b75843ce3782c68dbeb763351c08fd505
   language_server-protocol (3.17.0.5) sha256=fd1e39a51a28bf3eec959379985a72e296e9f9acfce46f6a79d31ca8760803cc
   lint_roller (1.1.0) sha256=2c0c845b632a7d172cb849cc90c1bce937a28c5c8ccccb50dfd46a485003cc87
+  method_source (1.1.0) sha256=181301c9c45b731b4769bc81e8860e72f9161ad7d66dd99103c9ab84f560f5c5
   parallel (1.27.0) sha256=4ac151e1806b755fb4e2dc2332cbf0e54f2e24ba821ff2d3dcf86bf6dc4ae130
   parser (3.3.10.1) sha256=06f6a725d2cd91e5e7f2b7c32ba143631e1f7c8ae2fb918fc4cebec187e6a688
   pp (0.6.3) sha256=2951d514450b93ccfeb1df7d021cae0da16e0a7f95ee1e2273719669d0ab9df6
   prettyprint (0.2.0) sha256=2bc9e15581a94742064a3cc8b0fb9d45aae3d03a1baa6ef80922627a0766f193
   prism (1.8.0) sha256=84453a16ef5530ea62c5f03ec16b52a459575ad4e7b9c2b360fd8ce2c39c1254
+  pry (0.16.0) sha256=d76c69065698ed1f85e717bd33d7942c38a50868f6b0673c636192b3d1b6054e
   psych (5.3.1) sha256=eb7a57cef10c9d70173ff74e739d843ac3b2c019a003de48447b2963d81b1974
   racc (1.8.1) sha256=4a7f6929691dbec8b5209a0b373bc2614882b55fc5d2e447a21aaa691303d62f
   rainbow (3.1.1) sha256=039491aa3a89f42efa1d6dec2fc4e62ede96eb6acd95e52f1ad581182b79bc6a
@@ -114,6 +126,7 @@ CHECKSUMS
   rspec-support (3.13.6) sha256=2e8de3702427eab064c9352fe74488cc12a1bfae887ad8b91cba480ec9f8afb2
   rubocop (1.82.1) sha256=09f1a6a654a960eda767aebea33e47603080f8e9c9a3f019bf9b94c9cab5e273
   rubocop-ast (1.49.0) sha256=49c3676d3123a0923d333e20c6c2dbaaae2d2287b475273fddee0c61da9f71fd
+  ruby-libgd (0.2.3) sha256=9ddf757d1abcc5d44166e30b3204b95579f561e2ed4f366ef2c5ffa6cc669c50
   ruby-progressbar (1.13.0) sha256=80fc9c47a9b640d6834e0dc7b3c94c9df37f08cb072b7761e4a71e22cff29b33
   stringio (3.2.0) sha256=c37cb2e58b4ffbd33fe5cd948c05934af997b36e0b6ca6fdf43afa234cf222e1
   tsort (0.2.0) sha256=9650a793f6859a43b6641671278f79cfead60ac714148aabe4e3f0060480089f
diff --git a/imprint.gemspec b/imprint.gemspec
index a98ad58..9e4b452 100644
--- a/imprint.gemspec
+++ b/imprint.gemspec
@@ -35,7 +35,7 @@ Gem::Specification.new do |spec|
 
   # Uncomment to register a new dependency of your gem
   # spec.add_dependency "example-gem", "~> 1.0"
-
+  spec.add_dependency 'ruby-libgd'
   # For more information and examples about making a new gem, check out our
   # guide at: https://bundler.io/guides/creating_gem.html
 end
diff --git a/lib/imprint.rb b/lib/imprint.rb
index 7d6c324..441349a 100644
--- a/lib/imprint.rb
+++ b/lib/imprint.rb
@@ -2,6 +2,8 @@
 
 require 'imprint/version'
 require 'imprint/signer'
+require 'imprint/renderer'
+require 'imprint/engine' if defined?(Rails)
 
 module Imprint
   def self.sign(source:, watermark:, expires_in:)
@@ -24,6 +26,16 @@ def self.verify(token)
     payload
   end
 
+  def self.render_from_token(token)
+    payload = verify(token)
+    return nil unless payload
+
+    Renderer.render(
+      source: payload['source'],
+      watermark: payload['watermark']
+    )
+  end
+
   def self.secret_key
     # sin engine todavía; Rails solo si existe
     if defined?(Rails)
diff --git a/lib/imprint/config/routes.rb b/lib/imprint/config/routes.rb
new file mode 100644
index 0000000..ec6bfa3
--- /dev/null
+++ b/lib/imprint/config/routes.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+Imprint::Engine.routes.draw do
+  get 'render/:token', to: 'renders#show'
+end
diff --git a/lib/imprint/controllers/imprint/renders_controller.rb b/lib/imprint/controllers/imprint/renders_controller.rb
new file mode 100644
index 0000000..3ff4828
--- /dev/null
+++ b/lib/imprint/controllers/imprint/renders_controller.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module Imprint
+  class RendersController < ActionController::Base
+    def show
+      path = Imprint.render_from_token(params[:token])
+
+      return head :not_found unless path && File.exist?(path)
+
+      send_file(
+        path,
+        type: 'image/png',
+        disposition: 'inline',
+        cache_control: 'no-store'
+      )
+    end
+  end
+end
diff --git a/lib/imprint/engine.rb b/lib/imprint/engine.rb
new file mode 100644
index 0000000..ed9d0d9
--- /dev/null
+++ b/lib/imprint/engine.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require 'rails'
+
+module Imprint
+  class Engine < ::Rails::Engine
+    isolate_namespace Imprint
+  end
+end
diff --git a/lib/imprint/renderer.rb b/lib/imprint/renderer.rb
new file mode 100644
index 0000000..b9793ff
--- /dev/null
+++ b/lib/imprint/renderer.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require 'pry'
+require 'gd'
+require 'securerandom'
+require 'tmpdir'
+
+module Imprint
+  class Renderer
+    DEFAULT_FONT_SIZE = 24
+
+    def self.render(source:, watermark:)
+      raise ArgumentError, 'source image not found' unless File.exist?(source)
+
+      image = GD::Image.open(source)
+
+      apply_watermark(image, watermark)
+
+      output = File.join(
+        Dir.tmpdir,
+        "imprint-#{SecureRandom.hex(8)}.png"
+      )
+
+      image.save(output)
+      output
+    end
+
+    def self.apply_watermark(image, text)
+      color = GD::Color.rgba(0, 116, 139, 225)
+
+      raise "Font missing" unless File.exist?(default_font)
+
+      image.text(
+        text,
+        x: 20,
+        y: image.height - 20,
+        size: DEFAULT_FONT_SIZE,
+        color: color,
+        font: default_font
+      )
+    end
+
+    def self.default_font
+      @default_font ||= begin
+        font = '/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf'
+        raise 'Font not found' unless File.exist?(font)
+
+        font
+      end
+    end
+  end
+end
diff --git a/spec/fixtures/sample.png b/spec/fixtures/sample.png
new file mode 100644
index 0000000..3905f93
Binary files /dev/null and b/spec/fixtures/sample.png differ
diff --git a/spec/fixtures/source.png b/spec/fixtures/source.png
new file mode 100644
index 0000000..dca86c4
Binary files /dev/null and b/spec/fixtures/source.png differ
diff --git a/spec/imprint_render_from_token_spec.rb b/spec/imprint_render_from_token_spec.rb
new file mode 100644
index 0000000..3b48a38
--- /dev/null
+++ b/spec/imprint_render_from_token_spec.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'gd'
+
+RSpec.describe Imprint do
+  before do
+    FileUtils.mkdir_p('spec/fixtures')
+
+    image = GD::Image.new(200, 100)
+    white = GD::Color.rgb(255, 255, 255)
+    image.fill(white)
+    image.save('spec/fixtures/source.png')
+  end
+
+  it 'renders image when token is valid' do
+    token = Imprint.sign(
+      source: 'spec/fixtures/source.png',
+      watermark: 'CONFIDENTIAL',
+      expires_in: 60
+    ).split('/').last
+
+    output = Imprint.render_from_token(token)
+
+    expect(output).to be_a(String)
+    expect(File).to exist(output)
+  end
+
+  it 'returns nil for expired token' do
+    token = Imprint.sign(
+      source: 'spec/fixtures/source.png',
+      watermark: 'CONFIDENTIAL',
+      expires_in: -1
+    ).split('/').last
+
+    expect(Imprint.render_from_token(token)).to be_nil
+  end
+end
diff --git a/spec/imprint_renderer_spec.rb b/spec/imprint_renderer_spec.rb
new file mode 100644
index 0000000..4a81051
--- /dev/null
+++ b/spec/imprint_renderer_spec.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Imprint::Renderer do
+  it 'renders an image with watermark' do
+    output = described_class.render(
+      source: 'spec/fixtures/sample.png',
+      watermark: 'CONFIDENTIAL'
+    )
+
+    expect(File).to exist(output)
+    expect(File.size(output)).to be > 0
+  end
+end