diff --git a/lib/docurest.rb b/lib/docurest.rb
index ea1b88c..00bfb63 100644
--- a/lib/docurest.rb
+++ b/lib/docurest.rb
@@ -1,5 +1,31 @@
 require "docurest/version"
 
+require "docurest/field"
+
+require "docurest/client"
+require "docurest/client/oauth"
+require "docurest/client/password"
+
+require "docurest/base"
+
+require "docurest/envelope"
+require "docurest/envelope/document"
+require "docurest/envelope/recipient"
+require "docurest/envelope/recipient/tab"
+
+require "docurest/login"
+
 module Docurest
-  # Your code goes here...
+  class << self
+    attr_accessor :client
+
+    def with_client(other_client)
+      old_client = @client
+      @client = other_client
+
+      yield if block_given?
+    ensure
+      @client = old_client
+    end
+  end
 end
diff --git a/lib/docurest/client.rb b/lib/docurest/client.rb
new file mode 100644
index 0000000..d335942
--- /dev/null
+++ b/lib/docurest/client.rb
@@ -0,0 +1,86 @@
+require "json"
+require "net/http"
+
+module Docurest
+  class Client
+    def initialize(account_id: nil, base_url: nil, env: :test)
+      @account_id = account_id
+      @base_url = base_url
+      @env = env
+    end
+
+    def delete(url, body, use_base_url: true, parse_json: true)
+      request = Net::HTTP::Delete.new build_uri(url, use_base_url),
+        {'Content-Type' => 'application/json'}
+      request.body = JSON.generate(body)
+      query request, parse_json: parse_json
+    end
+
+    def get(url, request_query = {}, use_base_url: true, parse_json: true)
+      uri = build_uri(url, use_base_url)
+      uri.query = URI.encode_www_form(request_query)
+
+      request = Net::HTTP::Get.new uri
+      query request, parse_json: parse_json
+    end
+
+    def post(url, body, use_base_url: true, parse_json: true)
+      request = Net::HTTP::Post.new build_uri(url, use_base_url),
+        {'Content-Type' => 'application/json'}
+      request.body = JSON.generate(body)
+      query request, parse_json: parse_json
+    end
+
+    def put(url, body, use_base_url: true, parse_json: true)
+      request = Net::HTTP::Put.new build_uri(url, use_base_url),
+        {'Content-Type' => 'application/json'}
+      request.body = JSON.generate(body)
+      query request, parse_json: parse_json
+    end
+
+    def query(request, parse_json:)
+      add_authentication_header request
+
+      res = Net::HTTP.start(request.uri.hostname, request.uri.port, use_ssl: request.uri.scheme == 'https') do |http|
+        http.request request
+      end
+
+      if parse_json
+        JSON.parse res.body
+      else
+        res.body
+      end
+    end
+
+    private
+
+    def add_authentication_header(request)
+    end
+
+    def base_url
+      @base_url ||= begin
+        account = Docurest::Login.information[:accounts].detect do |acc|
+          (@account_id && (acc.id == @account_id || acc.guid == @account_id)) || acc.default
+        end
+        if account
+          @account_id = account.id
+          "#{account.url}"
+        else
+          api_url
+        end
+      end
+    end
+
+    def api_url
+      if @env == :production
+        "https://www.docusign.net/restapi/#{API_VERSION}"
+      else
+        "https://demo.docusign.net/restapi/#{API_VERSION}"
+      end
+    end
+
+    def build_uri(url, use_base_url = true)
+      URI("#{use_base_url ? base_url : api_url}#{url}")
+    end
+  end
+end
diff --git a/lib/docurest/client/oauth.rb b/lib/docurest/client/oauth.rb
new file mode 100644
index 0000000..877081f
--- /dev/null
+++ b/lib/docurest/client/oauth.rb
@@ -0,0 +1,16 @@
+module Docurest
+  class Client::Oauth < Docurest::Client
+    AUTHENTICATION_HEADER = 'Authorization'
+
+    def initialize(access_token, **options)
+      super options
+      @access_token = access_token
+    end
+
+    private
+
+    def add_authentication_header(request)
+      request[AUTHENTICATION_HEADER] = "bearer#{@access_token}" if @access_token
+    end
+  end
+end
diff --git a/lib/docurest/client/password.rb b/lib/docurest/client/password.rb
new file mode 100644
index 0000000..a006fad
--- /dev/null
+++ b/lib/docurest/client/password.rb
@@ -0,0 +1,22 @@
+module Docurest
+  class Client::Password < Docurest::Client
+    AUTHENTICATION_HEADER = 'X-DocuSign-Authentication'
+
+    def initialize(username, password, integrator_key, **options)
+      super options
+      @username = username
+      @password = password
+      @integrator_key = integrator_key
+    end
+
+    private
+
+    def add_authentication_header(request)
+      request[AUTHENTICATION_HEADER] = JSON.generate({
+        "Username" => @username,
+        "Password" => @password,
+        "IntegratorKey" => @integrator_key,
+      })
+    end
+  end
+end
diff --git a/lib/docurest/version.rb b/lib/docurest/version.rb
index 05f268b..d9551af 100644
--- a/lib/docurest/version.rb
+++ b/lib/docurest/version.rb
@@ -1,3 +1,4 @@
 module Docurest
   VERSION = "0.1.0"
+  API_VERSION = "v2"
 end