diff --git a/.env.test b/.env.test
new file mode 100644
index 0000000..9f2753a
--- /dev/null
+++ b/.env.test
@@ -0,0 +1,3 @@
+PORT=4001
+DATABASE_URL=sqlite3://./sqlite/data.test.db?journal_mode=wal&synchronous=normal&foreign_keys=true
+APP_URL=http://localhost:4001
diff --git a/shard.lock b/shard.lock
index 2125b7f..dc5c0bf 100644
--- a/shard.lock
+++ b/shard.lock
@@ -10,11 +10,11 @@ shards:
 
   db:
     git: https://github.com/crystal-lang/crystal-db.git
-    version: 0.13.1
+    version: 0.11.0
 
   dotenv:
     git: https://github.com/gdotdesign/cr-dotenv.git
-    version: 0.6.0
+    version: 1.0.0
 
   exception_page:
     git: https://github.com/crystal-loot/exception_page.git
@@ -24,15 +24,27 @@ shards:
     git: https://github.com/kemalcr/kemal.git
     version: 1.5.0
 
+  micrate:
+    git: https://github.com/amberframework/micrate.git
+    version: 0.15.1
+
+  mysql:
+    git: https://github.com/crystal-lang/crystal-mysql.git
+    version: 0.14.0
+
+  pg:
+    git: https://github.com/will/crystal-pg.git
+    version: 0.26.0
+
   radix:
     git: https://github.com/luislavena/radix.git
     version: 0.4.1
 
   spec-kemal:
     git: https://github.com/kemalcr/spec-kemal.git
-    version: 0.5.0
+    version: 1.0.0
 
   sqlite3:
     git: https://github.com/crystal-lang/crystal-sqlite3.git
-    version: 0.21.0
+    version: 0.19.0
 
diff --git a/shard.yml b/shard.yml
index 54dc8e4..ac91c9a 100644
--- a/shard.yml
+++ b/shard.yml
@@ -5,8 +5,10 @@ authors:
   - Juan Rodriguez <sjdonado@icloud.com>
 
 targets:
-  pa:
-    main: src/url-shortener.cr
+  url-shortener:
+    main: url-shortener.cr
+  cli:
+    main: scripts/cli.cr
 
 dependencies:
   kemal:
@@ -21,6 +23,9 @@ development_dependencies:
     github: gdotdesign/cr-dotenv
   spec-kemal:
     github: kemalcr/spec-kemal
+  micrate:
+    github: amberframework/micrate
+    version: 0.15.1
 
 crystal: '>= 1.12.1'
 
diff --git a/spec/integration/link_spec.cr b/spec/integration/link_spec.cr
new file mode 100644
index 0000000..e78ee74
--- /dev/null
+++ b/spec/integration/link_spec.cr
@@ -0,0 +1,226 @@
+require "../spec_helper"
+require "../../app/models/*"
+
+API_KEY = Random::Secure.urlsafe_base64()
+
+describe App::Controllers::Link do
+  describe "Create" do
+    it "should create link" do
+      test_user = create_test_user()
+
+      payload = {"url" => "https://kagi.com"}
+      post(
+        "/api/links",
+        headers: HTTP::Headers{"Content-Type" => "application/json", "X-Api-Key" => test_user.api_key.to_s},
+        body: payload.to_json
+      )
+
+      parsed_response = Hash(String, Hash(String, String | Int64)).from_json(response.body)
+      parsed_response["data"]["origin"].should eq(payload["url"])
+    end
+
+    it "should return 400 - url required field" do
+      test_user = create_test_user()
+
+      payload = {"test" => "https://kagi.com"}
+      post(
+        "/api/links",
+        headers: HTTP::Headers{"Content-Type" => "application/json", "X-Api-Key" => test_user.api_key.to_s},
+        body: payload.to_json
+      )
+
+      expected = {"error" => "url: Required field"}.to_json
+      response.body.should eq(expected)
+    end
+
+    it "should return 400 - invalid url" do
+      test_user = create_test_user()
+
+      payload = {"url" => "test" }
+      post(
+        "/api/links",
+        headers: HTTP::Headers{"Content-Type" => "application/json", "X-Api-Key" => test_user.api_key.to_s},
+        body: payload.to_json
+      )
+
+      expected = {"errors" => {"url" => ["is invalid"]}}.to_json
+      response.body.should eq(expected)
+    end
+
+    it "should return 401 - missing api key" do
+      payload = {"url" => "https://kagi.com"}
+      post("/api/links", headers: HTTP::Headers{"Content-Type" => "application/json"}, body: payload.to_json)
+
+      expected = {"error" => "Unauthorized"}.to_json
+      response.status_code.should eq(401)
+      response.body.should eq(expected)
+    end
+  end
+
+  describe "Index" do
+    it "should redirect to origin domain" do
+      link = "https://kagi.com"
+      test_user = create_test_user()
+
+      test_link = create_test_link(test_user, link)
+      serialized_link = App::Serializers::Link.new(test_link)
+
+      get(serialized_link.refer, headers: HTTP::Headers{"X-Api-Key" => test_user.api_key.to_s})
+
+      response.headers["Location"].should eq(link)
+    end
+
+    it "should increase click counter after redirect" do
+      link = "https://kagi.com"
+      test_user = create_test_user()
+
+      test_link = create_test_link(test_user, link)
+      serialized_link = App::Serializers::Link.new(test_link)
+
+      get(serialized_link.refer, headers: HTTP::Headers{"X-Api-Key" => test_user.api_key.to_s})
+
+      updated_test_link = get_test_link(test_link.id)
+
+      response.headers["Location"].should eq(link)
+      updated_test_link.click_counter.should eq(1)
+    end
+
+    it "should return 404 - link does not exist" do
+      link = "https://kagi.com"
+      test_user = create_test_user()
+
+      test_link = create_test_link(test_user, link)
+      serialized_link = App::Serializers::Link.new(test_link)
+
+      delete_test_link(test_link.id)
+
+      get(serialized_link.refer, headers: HTTP::Headers{"X-Api-Key" => test_user.api_key.to_s})
+
+      expected = {"error" => "Not Found"}.to_json
+      response.status_code.should eq(404)
+      response.body.should eq(expected)
+    end
+  end
+
+  describe "All" do
+    it "should return all links" do
+      links = ["https://google.com", "google.com", "google.com.co"]
+      test_user = create_test_user()
+
+      links.each do |link|
+        create_test_link(test_user, link)
+      end
+
+      get("/api/links", headers: HTTP::Headers{"X-Api-Key" => test_user.api_key.to_s})
+
+      parsed_response = Hash(String, Array(Hash(String, String | Int64))).from_json(response.body)
+      parsed_response["data"][0]["origin"].should eq(links[0])
+      parsed_response["data"][1]["origin"].should eq(links[1])
+      parsed_response["data"][2]["origin"].should eq(links[2])
+    end
+
+    it "should return owned links only" do
+      links = ["https://google.com", "google.com", "google.com.co", "kagi.com"]
+      test_user = create_test_user()
+
+      links[0..2].each do |link|
+        create_test_link(test_user, link)
+      end
+
+      test_other_user = create_test_user()
+      create_test_link(test_other_user, links[3])
+
+      get("/api/links", headers: HTTP::Headers{"X-Api-Key" => test_user.api_key.to_s})
+
+      parsed_response = Hash(String, Array(Hash(String, String | Int64))).from_json(response.body)
+      parsed_response["data"].size.should eq(3)
+      parsed_response["data"][0]["origin"].should eq(links[0])
+      parsed_response["data"][1]["origin"].should eq(links[1])
+      parsed_response["data"][2]["origin"].should eq(links[2])
+    end
+
+    it "should return 401 - missing api key" do
+      get "/api/links"
+
+      expected = {"error" => "Unauthorized"}.to_json
+      response.status_code.should eq(401)
+      response.body.should eq(expected)
+    end
+  end
+
+  describe "Update" do
+    it "should update link url" do
+      link = "https://kagi.com"
+      test_user = create_test_user()
+      test_link = create_test_link(test_user, link)
+
+      payload = {"url" => "https://kagi.com.co"}
+      put(
+        "/api/links/#{test_link.id}",
+        headers: HTTP::Headers{"Content-Type" => "application/json", "X-Api-Key" => test_user.api_key.to_s},
+        body: payload.to_json
+      )
+
+      parsed_response = Hash(String, Hash(String, String | Int64)).from_json(response.body)
+      parsed_response["data"]["origin"].should eq(payload["url"])
+    end
+
+    it "should return 404 - link does not exist" do
+      test_user = create_test_user()
+
+      payload = {"url" => "https://kagi.com.co"}
+      put(
+        "/api/links/1",
+        headers: HTTP::Headers{"Content-Type" => "application/json", "X-Api-Key" => test_user.api_key.to_s},
+        body: payload.to_json
+      )
+
+      expected = {"error" => "Not Found"}.to_json
+      response.status_code.should eq(404)
+      response.body.should eq(expected)
+    end
+
+    it "should return 401 - missing api key" do
+      payload = {"url" => "https://kagi.com.co"}
+      put(
+        "/api/links/1",
+        headers: HTTP::Headers{"Content-Type" => "application/json"},
+        body: payload.to_json
+      )
+
+      expected = {"error" => "Unauthorized"}.to_json
+      response.status_code.should eq(401)
+      response.body.should eq(expected)
+    end
+  end
+
+  describe "Delete" do
+    it "should delete link url" do
+      link = "https://kagi.com"
+      test_user = create_test_user()
+      test_link = create_test_link(test_user, link)
+
+      delete("/api/links/#{test_link.id}", headers: HTTP::Headers{"X-Api-Key" => test_user.api_key.to_s})
+
+      response.status_code.should eq(204)
+    end
+
+    it "should return 404 - link does not exist" do
+      test_user = create_test_user()
+
+      delete("/api/links/1", headers: HTTP::Headers{"X-Api-Key" => test_user.api_key.to_s})
+
+      expected = {"error" => "Not Found"}.to_json
+      response.status_code.should eq(404)
+      response.body.should eq(expected)
+    end
+
+    it "should return 401 - missing api key" do
+      delete "/api/links/1"
+
+      expected = {"error" => "Unauthorized"}.to_json
+      response.status_code.should eq(401)
+      response.body.should eq(expected)
+    end
+  end
+end
diff --git a/spec/pa_spec.cr b/spec/pa_spec.cr
deleted file mode 100644
index 21781a0..0000000
--- a/spec/pa_spec.cr
+++ /dev/null
@@ -1,9 +0,0 @@
-require "./spec_helper"
-
-describe Url::Shortener do
-  # TODO: Write tests
-
-  it "works" do
-    false.should eq(true)
-  end
-end
diff --git a/spec/spec_helper.cr b/spec/spec_helper.cr
index d022140..ea7dfd5 100644
--- a/spec/spec_helper.cr
+++ b/spec/spec_helper.cr
@@ -1,2 +1,48 @@
-require "spec"
-require "../src/pa"
+require "uuid"
+
+require "spec-kemal"
+require "micrate"
+
+require "../url-shortener"
+
+Spec.before_suite do
+  Micrate::DB.connection_url = ENV["DATABASE_URL"]
+  Micrate::Cli.run_up
+end
+
+def create_test_user
+  user = App::Models::User.new
+  user.id = UUID.v4.to_s
+  user.name = "Tester"
+  user.api_key = Random::Secure.urlsafe_base64()
+
+  changeset = App::Lib::Database.insert(user)
+  if !changeset.valid?
+    raise "Test user creation failed"
+  end
+
+  user
+end
+
+def create_test_link(user, url)
+  link = App::Models::Link.new
+  link.id = UUID.v4.to_s
+  link.url = url
+  link.slug = Random::Secure.urlsafe_base64(4)
+  link.user = user
+
+  changeset = App::Lib::Database.insert(link)
+  if !changeset.valid?
+    raise "Test link creation failed"
+  end
+
+  link
+end
+
+def get_test_link(link_id)
+  App::Lib::Database.get!(App::Models::Link, link_id)
+end
+
+def delete_test_link(link_id)
+  App::Lib::Database.raw_exec("DELETE FROM links WHERE id = (?)", link_id) # tempfix: Database.delete does not work
+end