diff --git a/Gemfile b/Gemfile
index 43ab3d5..2f263d7 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,6 +5,7 @@ ruby "3.1.1"
 gem "rails", "~> 7.0.2", ">= 7.0.2.2"
 gem "pg", "~> 1.1"
 gem "puma", "~> 5.0"
+gem "jbuilder"
 
 gem "bootsnap", require: false
 
@@ -13,5 +14,4 @@ group :development, :test do
 
   gem "rspec-rails", "~> 5.1"
   gem "factory_bot_rails", "~> 6.2"
-  gem "shoulda-matchers", "~> 5.1"
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index dadd9d3..489d888 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -90,6 +90,9 @@ GEM
     io-wait (0.2.1)
     irb (1.4.1)
       reline (>= 0.3.0)
+    jbuilder (2.11.5)
+      actionview (>= 5.0.0)
+      activesupport (>= 5.0.0)
     loofah (2.14.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
@@ -190,6 +193,7 @@ DEPENDENCIES
   bootsnap
   debug
   factory_bot_rails (~> 6.2)
+  jbuilder
   pg (~> 1.1)
   puma (~> 5.0)
   rails (~> 7.0.2, >= 7.0.2.2)
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
new file mode 100644
index 0000000..2a7816c
--- /dev/null
+++ b/app/controllers/users_controller.rb
@@ -0,0 +1,53 @@
+class UsersController < ApplicationController
+  before_action :set_user, only: %i[ show update destroy ]
+
+  # GET /users
+  # GET /users.json
+  def index
+    @users = User.all
+  end
+
+  # GET /users/1
+  # GET /users/1.json
+  def show
+  end
+
+  # POST /users
+  # POST /users.json
+  def create
+    @user = User.new(user_params)
+
+    if @user.save
+      render :show, status: :created, location: @user
+    else
+      render json: @user.errors, status: :unprocessable_entity
+    end
+  end
+
+  # PATCH/PUT /users/1
+  # PATCH/PUT /users/1.json
+  def update
+    if @user.update(user_params)
+      render :show, status: :ok, location: @user
+    else
+      render json: @user.errors, status: :unprocessable_entity
+    end
+  end
+
+  # DELETE /users/1
+  # DELETE /users/1.json
+  def destroy
+    @user.destroy
+  end
+
+  private
+    # Use callbacks to share common setup or constraints between actions.
+    def set_user
+      @user = User.find(params[:id])
+    end
+
+    # Only allow a list of trusted parameters through.
+    def user_params
+      params.require(:user).permit(:username)
+    end
+end
diff --git a/app/models/user.rb b/app/models/user.rb
new file mode 100644
index 0000000..0ed9edc
--- /dev/null
+++ b/app/models/user.rb
@@ -0,0 +1,10 @@
+class User < ApplicationRecord
+  validates :username,
+            presence: true,
+            uniqueness: true,
+            length: { maximum: 14 },
+            allow_nil: false,
+            format: {
+              with: /\A[a-zA-Z0-9]+\z/,
+            }
+end
diff --git a/app/views/users/_user.json.jbuilder b/app/views/users/_user.json.jbuilder
new file mode 100644
index 0000000..c88f34b
--- /dev/null
+++ b/app/views/users/_user.json.jbuilder
@@ -0,0 +1,2 @@
+json.extract! user, :id, :username, :created_at, :updated_at
+json.url user_url(user, format: :json)
diff --git a/app/views/users/index.json.jbuilder b/app/views/users/index.json.jbuilder
new file mode 100644
index 0000000..98788da
--- /dev/null
+++ b/app/views/users/index.json.jbuilder
@@ -0,0 +1 @@
+json.array! @users, partial: "users/user", as: :user
diff --git a/app/views/users/show.json.jbuilder b/app/views/users/show.json.jbuilder
new file mode 100644
index 0000000..ff40bb9
--- /dev/null
+++ b/app/views/users/show.json.jbuilder
@@ -0,0 +1 @@
+json.partial! "users/user", user: @user
diff --git a/config/routes.rb b/config/routes.rb
index 262ffd5..9fe51af 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,6 +1,5 @@
 Rails.application.routes.draw do
-  # Define your application routes per the DSL in https://guides.rubyonrails.org/routing.html
+  resources :users, only: [:show]
 
-  # Defines the root path route ("/")
-  # root "articles#index"
+  # Define your application routes per the DSL in https://guides.rubyonrails.org/routing.html
 end
diff --git a/db/migrate/20220227172543_create_users.rb b/db/migrate/20220227172543_create_users.rb
new file mode 100644
index 0000000..b81656f
--- /dev/null
+++ b/db/migrate/20220227172543_create_users.rb
@@ -0,0 +1,9 @@
+class CreateUsers < ActiveRecord::Migration[7.0]
+  def change
+    create_table :users do |t|
+      t.string :username, null: false, limit: 14, index: true
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index b783f98..e4d1bb4 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,8 +10,15 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.0].define(version: 0) do
+ActiveRecord::Schema[7.0].define(version: 2022_02_27_172543) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
+  create_table "users", force: :cascade do |t|
+    t.string "username", limit: 14, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["username"], name: "index_users_on_username"
+  end
+
 end
diff --git a/db/seeds.rb b/db/seeds.rb
index bc25fce..83e1657 100644
--- a/db/seeds.rb
+++ b/db/seeds.rb
@@ -1,7 +1,3 @@
-# This file should contain all the record creation needed to seed the database with its default values.
-# The data can then be loaded with the bin/rails db:seed command (or created alongside the database with db:setup).
-#
-# Examples:
-#
-#   movies = Movie.create([{ name: "Star Wars" }, { name: "Lord of the Rings" }])
-#   Character.create(name: "Luke", movie: movies.first)
+User.find_or_create_by(username: 'xpto')
+User.find_or_create_by(username: 'admin')
+User.find_or_create_by(username: 'geonizeli')
\ No newline at end of file
diff --git a/spec/factories/users.rb b/spec/factories/users.rb
new file mode 100644
index 0000000..99925c3
--- /dev/null
+++ b/spec/factories/users.rb
@@ -0,0 +1,5 @@
+FactoryBot.define do
+  factory :user do
+    username { "xpto" }
+  end
+end
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
new file mode 100644
index 0000000..6650589
--- /dev/null
+++ b/spec/models/user_spec.rb
@@ -0,0 +1,36 @@
+require 'rails_helper'
+
+RSpec.describe User, type: :model do
+  describe 'validations' do
+    describe 'username' do
+      it 'presence' do
+        user = build(:user, username: nil)
+
+        expect(user).to_not be_valid
+      end
+
+      it 'uniqueness' do
+        create(:user, username: 'xpto')
+        user = build(:user, username: 'xpto')
+
+        expect(user).to_not be_valid
+      end
+
+      it 'max length 14' do
+        with_15_caracters = build(:user, username: 'asdfghjklzxcvhn')
+        with_14_caracters = build(:user, username: 'asdfghjklzxcvh')
+
+        expect(with_15_caracters).to_not be_valid
+        expect(with_14_caracters).to be_valid
+      end
+
+      it 'format' do
+        with_invalid_format = build(:user, username: 'asdfghjklzxcvh!')
+        with_valid_format = build(:user, username: 'asdfghjklzxcvh')
+
+        expect(with_invalid_format).to_not be_valid
+        expect(with_valid_format).to be_valid
+      end
+    end
+  end
+end
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index c0c0dcc..7a193e8 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -34,6 +34,8 @@ RSpec.configure do |config|
   # Remove this line if you're not using ActiveRecord or ActiveRecord fixtures
   config.fixture_path = "#{::Rails.root}/spec/fixtures"
 
+  config.include FactoryBot::Syntax::Methods
+
   # If you're not using ActiveRecord, or you'd prefer not to run each of your
   # examples within a transaction, remove the following line or assign false
   # instead of true.
@@ -62,10 +64,3 @@ RSpec.configure do |config|
   # arbitrary gems may also be filtered via:
   # config.filter_gems_from_backtrace("gem name")
 end
-
-Shoulda::Matchers.configure do |config|
-  config.integrate do |with|
-    with.test_framework :rspec
-    with.library :rails
-  end
-end
diff --git a/spec/requests/users_spec.rb b/spec/requests/users_spec.rb
new file mode 100644
index 0000000..b53e693
--- /dev/null
+++ b/spec/requests/users_spec.rb
@@ -0,0 +1,17 @@
+require 'rails_helper'
+
+RSpec.describe "/users", type: :request do
+  let(:valid_attributes) {
+    {
+      username: 'geonizeli'
+    }
+  }
+
+  describe "GET /show" do
+    it "renders a successful response" do
+      user = User.create! valid_attributes
+      get user_url(user), as: :json
+      expect(response).to be_successful
+    end
+  end
+end
diff --git a/spec/routing/users_routing_spec.rb b/spec/routing/users_routing_spec.rb
new file mode 100644
index 0000000..2efa471
--- /dev/null
+++ b/spec/routing/users_routing_spec.rb
@@ -0,0 +1,9 @@
+require "rails_helper"
+
+RSpec.describe UsersController, type: :routing do
+  describe "routing" do
+    it "routes to #show" do
+      expect(get: "/users/1").to route_to("users#show", id: "1")
+    end
+  end
+end