diff --git a/Gemfile.lock b/Gemfile.lock
index 513c283..991b400 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,47 +1,47 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.8.6)
-      public_suffix (>= 2.0.2, < 6.0)
-    bigdecimal (3.1.6)
-    connection_pool (2.4.1)
+    addressable (2.8.7)
+      public_suffix (>= 2.0.2, < 7.0)
+    bigdecimal (3.2.2)
+    connection_pool (2.5.3)
     crack (1.0.0)
       bigdecimal
       rexml
-    diff-lcs (1.5.1)
-    faraday (2.12.0)
-      faraday-net_http (>= 2.0, < 3.4)
+    diff-lcs (1.6.2)
+    faraday (2.13.1)
+      faraday-net_http (>= 2.0, < 3.5)
       json
       logger
-    faraday-net_http (3.3.0)
-      net-http
+    faraday-net_http (3.4.0)
+      net-http (>= 0.5.0)
     faraday-net_http_persistent (2.3.0)
       faraday (~> 2.5)
       net-http-persistent (>= 4.0.4, < 5)
-    hashdiff (1.1.0)
-    json (2.7.2)
-    logger (1.6.1)
-    net-http (0.4.1)
+    hashdiff (1.2.0)
+    json (2.12.2)
+    logger (1.7.0)
+    net-http (0.6.0)
       uri
-    net-http-persistent (4.0.4)
-      connection_pool (~> 2.2)
-    public_suffix (5.0.4)
-    rexml (3.2.6)
-    rspec (3.13.0)
+    net-http-persistent (4.0.6)
+      connection_pool (~> 2.2, >= 2.2.4)
+    public_suffix (6.0.2)
+    rexml (3.4.1)
+    rspec (3.13.1)
       rspec-core (~> 3.13.0)
       rspec-expectations (~> 3.13.0)
       rspec-mocks (~> 3.13.0)
-    rspec-core (3.13.0)
+    rspec-core (3.13.4)
       rspec-support (~> 3.13.0)
-    rspec-expectations (3.13.0)
+    rspec-expectations (3.13.5)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
-    rspec-mocks (3.13.0)
+    rspec-mocks (3.13.5)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
-    rspec-support (3.13.0)
-    uri (0.13.1)
-    webmock (3.22.0)
+    rspec-support (3.13.4)
+    uri (1.0.3)
+    webmock (3.25.1)
       addressable (>= 2.8.0)
       crack (>= 0.3.2)
       hashdiff (>= 0.4.0, < 2.0.0)
diff --git a/lib/rubyai.rb b/lib/rubyai.rb
index 211a3bc..5a9d381 100644
--- a/lib/rubyai.rb
+++ b/lib/rubyai.rb
@@ -2,11 +2,31 @@
 require 'faraday/net_http_persistent'
 require 'json'
 
+require_relative "rubyai/providers/openai"
+require_relative "rubyai/providers/anthropic"
+require_relative "rubyai/provider"
 require_relative "rubyai/client"
 require_relative "rubyai/configuration"
 require_relative "rubyai/http"
+require_relative "rubyai/chat"
 require_relative "rubyai/version"
 
 module RubyAI
   class Error < StandardError; end
+
+  def self.models 
+    Configuration::MODELS
+  end
+
+  def self.chat(config = {})
+    Client.new(config).call
+  end
+
+  def self.configure
+    yield config
+  end
+
+  def self.config(config = {})
+    @config ||= Configuration.new(config)
+  end
 end
diff --git a/lib/rubyai/chat.rb b/lib/rubyai/chat.rb
new file mode 100644
index 0000000..e86688f
--- /dev/null
+++ b/lib/rubyai/chat.rb
@@ -0,0 +1,41 @@
+module RubyAI
+  class Chat
+    attr_accessor :provider, :model, :temperature
+    
+    def initialize(provider, model: nil, temperature: 0.7)
+      @provider = provider
+      @model = model || RubyAI::Configuration::DEFAULT_MODEL
+      @temperature = temperature
+    end
+
+    def call(messages)
+      raise ArgumentError, "Messages cannot be empty" if messages.nil? || messages.empty?
+
+      body = HTTP.build_body(messages, @provider, @model, @temperature)
+      headers = HTTP.build_headers(provider, RubyAI.config)
+
+      response = connection.post do |req|
+        req.url Configuration::PROVIDERS[@provider] || Configuration::BASE_URL
+        req.headers.merge!(headers)
+        req.body = body.to_json
+      end
+
+      JSON.parse(response.body)
+    end
+
+    private
+
+    def connection
+      @connection ||= Faraday.new do |faraday|
+        faraday.adapter Faraday.default_adapter
+        faraday.headers['Content-Type'] = 'application/json'
+      end
+    rescue Faraday::Error => e
+      raise "Connection error: #{e.message}"
+    rescue JSON::ParserError => e
+      raise "Response parsing error: #{e.message}"
+    rescue StandardError => e
+      raise "An unexpected error occurred: #{e.message}"  
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/rubyai/client.rb b/lib/rubyai/client.rb
index 6cbc096..7380792 100644
--- a/lib/rubyai/client.rb
+++ b/lib/rubyai/client.rb
@@ -2,15 +2,15 @@ module RubyAI
   class Client
     attr_reader :configuration
 
-    def initialize(config_hash = {})
-      @configuration = Configuration.new(config_hash)
+    def initialize(config = {})
+      @configuration ||= RubyAI.config(config)
     end
 
     def call
       response = connection.post do |req|
-        req.url Configuration::BASE_URL
-        req.headers.merge!(HTTP.build_headers(configuration.api_key))
-        req.body = HTTP.build_body(configuration.messages, configuration.model, configuration.temperature).to_json
+        req.url Configuration::PROVIDERS[configuration.provider] || Configuration::BASE_URL
+        req.headers.merge!(HTTP.build_headers(configuration.provider || RubyAI::Configuration::DEFAULT_PROVIDER, RubyAI.config ))
+        req.body = HTTP.build_body(configuration.messages, configuration.provider, configuration.model, configuration.temperature).to_json
       end
 
       JSON.parse(response.body)
diff --git a/lib/rubyai/configuration.rb b/lib/rubyai/configuration.rb
index ed0bc1b..3e0b9fa 100644
--- a/lib/rubyai/configuration.rb
+++ b/lib/rubyai/configuration.rb
@@ -1,31 +1,42 @@
 module RubyAI
   class Configuration
-    BASE_URL = "https://api.openai.com/v1/chat/completions"
+    PROVIDERS = { 
+      'openai' => "https://api.openai.com/v1/chat/completions",
+      'anthropic' => "https://api.anthropic.com/v1/chat/completions"
+      }.freeze
+
+    MODELS = PROVIDERS.to_h do |provider, _url|
+        [provider, Provider[provider].models]
+      end.freeze
 
-    MODELS = {
-      "gpt-4" => "gpt-4",
-      "gpt-4-32k" => "gpt-4-32k",
-      "gpt-4-turbo" => "gpt-4-turbo",
-      "gpt-4o-mini" => "gpt-4o-mini",
-      "o1-mini" => "o1-mini",
-      "o1-preview" => "o1-preview",
-      "text-davinci-003" => "text-davinci-003"
-    }
+
+    BASE_URL = "https://api.openai.com/v1/chat/completions"
 
     DEFAULT_MODEL = "gpt-3.5-turbo"
 
-    attr_accessor :api_key, :model, :messages, :temperature
+    DEFAULT_PROVIDER = 'openai'
+
+    # default values for configuration
+    attr_accessor :api_key,
+                  :model, 
+                  :messages, 
+                  :temperature, 
+                  :provider,
+                  # :providers
+                  :anthropic_api_key
 
     def initialize(config = {})
-      @api_key = config[:api_key]
+      @api_key = config.fetch(:api_key, openai_api_key) 
+      @openai_api_key = config.fetch(:openai_api_key, api_key) 
       @model = config.fetch(:model, DEFAULT_MODEL)
       @messages = config.fetch(:messages, nil)
       @temperature = config.fetch(:temperature, 0.7)
+      @provider = config.fetch(:provider, "openai")
     end
   end
 
   def self.configuration
-    @configuration ||= Configuration.new
+    @configuration ||= RubyAI.config(config = {})
   end
 
   def self.configure
diff --git a/lib/rubyai/http.rb b/lib/rubyai/http.rb
index cd73806..aaf38e5 100644
--- a/lib/rubyai/http.rb
+++ b/lib/rubyai/http.rb
@@ -2,19 +2,49 @@ module RubyAI
   module HTTP
     extend self
 
-    def build_body(messages, model, temperature)
-      {
-        'model': Configuration::MODELS[model],
+    def build_body(messages, provider, model, temperature)
+      case provider 
+      when 'openai'
+        {
+        'model': Configuration::MODELS[provider][model],
         'messages': [{ "role": "user", "content": messages }],
         'temperature': temperature
-      }
+        }
+      when 'anthropic'
+        {
+          'model' => Configuration::MODELS[provider][model],
+          'max_tokens' => 1024, # Required parameter for Anthropic API
+          'messages' => format_messages_for_antropic(messages),
+          'temperature' => temperature
+        }
+      end
     end
 
-    def build_headers(api_key)
-      {
+    def build_headers(provider, config)
+      case provider 
+      when 'openai'
+        {
         'Content-Type': 'application/json',
-        'Authorization': "Bearer #{api_key}"
-      }
+        'Authorization': "Bearer #{config.openai_api_key}"
+        }
+      when 'anthropic'
+        {
+          'x-api-key' => config.anthropic_api_key,
+          'anthropic-version' => '2023-06-01'
+        }
+      end
+    end
+
+    private 
+
+    def format_messages_for_antropic(messages)
+      # Messages should be an array of message objects
+      # Each message needs 'role' (either 'user' or 'assistant') and 'content'
+      if messages.is_a?(String)
+        [{ 'role' => 'user', 'content' => messages }]
+      else
+        messages
+      end
     end
   end
 end
diff --git a/lib/rubyai/provider.rb b/lib/rubyai/provider.rb
new file mode 100644
index 0000000..8d52466
--- /dev/null
+++ b/lib/rubyai/provider.rb
@@ -0,0 +1,15 @@
+module RubyAI
+  module Provider  
+    PROVIDERS = {
+      'openai' => RubyAI::Providers::OpenAI,
+      # doesn't tested yet because i don't have an anthropic api key
+      'anthropic' => RubyAI::Providers::Anthropic
+    }
+
+    module_function 
+
+    def [](provider)
+      PROVIDERS.fetch(provider)
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/rubyai/providers/anthropic.rb b/lib/rubyai/providers/anthropic.rb
new file mode 100644
index 0000000..530c841
--- /dev/null
+++ b/lib/rubyai/providers/anthropic.rb
@@ -0,0 +1,17 @@
+module RubyAI
+  module Providers 
+    # doesn't tested yet because i don't have an anthropic api key
+    class Anthropic
+      def self.models = {
+        "claude-2" => "claude-2",
+        "claude-instant-100k" => "claude-instant-100k",
+        "claude-1" => "claude-1",
+        "claude-1.3" => "claude-1.3",
+        "claude-1.3-sonnet" => "claude-1.3-sonnet",
+        "claude-1.3-sonnet-100k" => "claude-1.3-sonnet-100k"
+      }.freeze
+    end
+
+    # todo: configuration of separate models
+  end
+end
\ No newline at end of file
diff --git a/lib/rubyai/providers/openai.rb b/lib/rubyai/providers/openai.rb
new file mode 100644
index 0000000..14f81e8
--- /dev/null
+++ b/lib/rubyai/providers/openai.rb
@@ -0,0 +1,20 @@
+module RubyAI
+  module Providers
+    class OpenAI 
+      DEFAULT_MODEL = "gpt-3.5-turbo".freeze
+
+      def self.models
+        {"gpt-3.5-turbo" => "gpt-3.5-turbo",
+        "gpt-4" => "gpt-4",
+        "gpt-4-32k" => "gpt-4-32k",
+        "gpt-4-turbo" => "gpt-4-turbo",
+        "gpt-4o-mini" => "gpt-4o-mini",
+        "o1-mini" => "o1-mini",
+        "o1-preview" => "o1-preview",
+        "text-davinci-003" => "text-davinci-003" }
+      end
+
+      # todo: configuration of separate models
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/configuration_spec.rb b/spec/configuration_spec.rb
deleted file mode 100644
index e9298f1..0000000
--- a/spec/configuration_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require 'webmock/rspec'
-require_relative '../lib/rubyai/client.rb'
-
-RSpec.describe RubyAI::Client do
-  let(:api_key) { 'your_api_key' }
-  let(:messages) { 'Hello, how are you?' }
-  let(:temperature) { 0.7 }
-  let(:model) { 'gpt-3.5-turbo' }
-
-  before do
-    RubyAI.configure do |config|
-      config.api_key = api_key
-      config.messages = messages
-    end
-  end
-
-  describe '#call' do
-    let(:response_body) { { 'choices' => [{ 'message' => { 'content' => 'This is a response from the model.' } }] } }
-    let(:status) { 200 }
-
-    before do
-      stub_request(:post, RubyAI::Configuration::BASE_URL)
-        .to_return(status: status, body: response_body.to_json, headers: { 'Content-Type' => 'application/json' })
-    end
-
-    it 'returns parsed JSON response when passing through client via configuration' do
-      configuration = { api_key: RubyAI.configuration.api_key, messages: RubyAI.configuration.messages }
-      client = described_class.new(configuration)
-      result = client.call
-      expect(result.dig('choices', 0, 'message', 'content')).to eq('This is a response from the model.')
-    end
-  end
-end
diff --git a/spec/rubyai/chat_spec.rb b/spec/rubyai/chat_spec.rb
new file mode 100644
index 0000000..fc13386
--- /dev/null
+++ b/spec/rubyai/chat_spec.rb
@@ -0,0 +1,2 @@
+require_relative '../../lib/rubyai/chat'
+require 'webmock/rspec'
diff --git a/spec/client_spec.rb b/spec/rubyai/client_spec.rb
similarity index 83%
rename from spec/client_spec.rb
rename to spec/rubyai/client_spec.rb
index f74c472..dfe3f03 100644
--- a/spec/client_spec.rb
+++ b/spec/rubyai/client_spec.rb
@@ -1,12 +1,13 @@
 require 'webmock/rspec'
-require_relative '../lib/rubyai/client.rb'
+require_relative '../../lib/rubyai/client.rb'
 
 RSpec.describe RubyAI::Client do
   let(:api_key) { 'your_api_key' }
   let(:messages) { 'Hello, how are you?' }
   let(:temperature) { 0.7 }
   let(:model) { 'gpt-3.5-turbo' }
-  let(:client) { described_class.new(api_key: api_key, messages: messages, temperature: temperature, model: model) }
+  let(:provider) { 'openai' }
+  let(:client) { described_class.new(api_key: api_key, messages: messages, temperature: temperature, provider: provider, model: model) }
 
   describe '#call' do
     let(:response_body) { { 'completion' => 'This is a response from the model.' } }
diff --git a/spec/rubyai/configuration_spec.rb b/spec/rubyai/configuration_spec.rb
new file mode 100644
index 0000000..81e8fe1
--- /dev/null
+++ b/spec/rubyai/configuration_spec.rb
@@ -0,0 +1,67 @@
+require 'webmock/rspec'
+require_relative '../../lib/rubyai/client'
+require_relative '../../lib/rubyai/providers/openai'
+require_relative '../../lib/rubyai/providers/anthropic'
+require_relative '../../lib/rubyai/provider'
+require_relative '../../lib/rubyai/configuration'
+
+
+RSpec.describe RubyAI::Client do
+  let(:api_key) { 'your_api_key' }
+  let(:messages) { 'Hello, how are you?' }
+  let(:temperature) { 0.7 }
+  let(:model) { 'gpt-3.5-turbo' }
+  let(:provider) { 'openai' }
+
+  before do
+    RubyAI.configure do |config|
+      config.provider = provider
+      config.model = model
+      config.temperature = temperature
+      config.api_key = api_key
+      config.messages = messages
+    end
+  end
+
+  describe '#call' do
+    let(:response_body) { { 'choices' => [{ 'message' => { 'content' => 'This is a response from the model.' } }] } }
+    let(:status) { 200 }
+
+    before do
+      stub_request(:post, RubyAI::Configuration::BASE_URL)
+        .to_return(status: status, body: response_body.to_json, headers: { 'Content-Type' => 'application/json' })
+    end
+
+    it 'returns parsed JSON response when passing through client via configuration' do
+      configuration = { api_key: RubyAI.configuration.api_key, messages: RubyAI.configuration.messages }
+      client = described_class.new(configuration)
+      result = client.call
+      expect(result.dig('choices', 0, 'message', 'content')).to eq('This is a response from the model.')
+    end
+  end
+
+  describe 'Constants' do 
+    specify "PROVIDERS" do 
+      expect(RubyAI::Configuration::PROVIDERS).to eq(
+                                                    'openai' => "https://api.openai.com/v1/chat/completions",
+                                                    'anthropic' => "https://api.anthropic.com/v1/chat/completions"
+      )
+    end
+
+    specify "MODELS should return Hash" do 
+      expect(RubyAI::Configuration::MODELS).to be_an_instance_of(Hash)
+    end
+
+    specify "BASE_URL" do 
+      expect(RubyAI::Configuration::BASE_URL).to eq("https://api.openai.com/v1/chat/completions")
+    end
+
+    specify "DEFAULT_MODEL" do 
+      expect(RubyAI::Configuration::DEFAULT_MODEL).to eq("gpt-3.5-turbo")
+    end
+
+    specify "DEFAULT_PROVIDER" do 
+      expect(RubyAI::Configuration::DEFAULT_PROVIDER).to eq("openai")
+    end
+  end
+end
diff --git a/spec/rubyai/http_spec.rb b/spec/rubyai/http_spec.rb
new file mode 100644
index 0000000..cc9b045
--- /dev/null
+++ b/spec/rubyai/http_spec.rb
@@ -0,0 +1,235 @@
+require_relative '../../lib/rubyai/http'
+
+RSpec.describe RubyAI::HTTP do
+  let(:config) do
+    double('config', 
+      openai_api_key: 'test-openai-key',
+      anthropic_api_key: 'test-anthropic-key'
+    )
+  end
+
+  let(:messages) { "Hello, how are you?" }
+  let(:temperature) { 0.7 }
+
+  # Mock the Configuration::MODELS constant
+  before do
+    stub_const('RubyAI::Configuration::MODELS', {
+      'openai' => {
+        'gpt-3.5-turbo' => 'gpt-3.5-turbo',
+        'gpt-4' => 'gpt-4'
+      },
+      'anthropic' => {
+        'claude-3-sonnet' => 'claude-3-sonnet-20240229',
+        'claude-3-haiku' => 'claude-3-haiku-20240307'
+      }
+    })
+  end
+
+  describe '.build_body' do
+    context 'when provider is openai' do
+      let(:provider) { 'openai' }
+      let(:model) { 'gpt-3.5-turbo' }
+
+      it 'returns correct body structure for OpenAI' do
+        result = described_class.build_body(messages, provider, model, temperature)
+
+        expect(result).to eq({
+          :'model' => 'gpt-3.5-turbo',
+          :'messages' => [{ :"role" => "user", :"content" => messages }],
+          :'temperature' => temperature
+        })
+      end
+
+      it 'uses the correct model mapping from configuration' do
+        model = 'gpt-4'
+        result = described_class.build_body(messages, provider, model, temperature)
+
+        expect(result[:model]).to eq('gpt-4')
+      end
+
+      it 'includes temperature parameter' do
+        custom_temp = 0.9
+        result = described_class.build_body(messages, provider, model, custom_temp)
+
+        expect(result[:temperature]).to eq(custom_temp)
+      end
+    end
+
+    context 'when provider is anthropic' do
+      let(:provider) { 'anthropic' }
+      let(:model) { 'claude-3-sonnet' }
+
+      it 'returns correct body structure for Anthropic' do
+        result = described_class.build_body(messages, provider, model, temperature)
+
+        expect(result).to eq({
+          'model' => 'claude-3-sonnet-20240229',
+          'max_tokens' => 1024,
+          'messages' => [{ 'role' => 'user', 'content' => messages }],
+          'temperature' => temperature
+        })
+      end
+
+      it 'uses the correct model mapping from configuration' do
+        model = 'claude-3-haiku'
+        result = described_class.build_body(messages, provider, model, temperature)
+
+        expect(result['model']).to eq('claude-3-haiku-20240307')
+      end
+
+      it 'includes required max_tokens parameter' do
+        result = described_class.build_body(messages, provider, model, temperature)
+
+        expect(result['max_tokens']).to eq(1024)
+      end
+
+      it 'formats messages correctly for single string input' do
+        result = described_class.build_body(messages, provider, model, temperature)
+
+        expect(result['messages']).to eq([{ 'role' => 'user', 'content' => messages }])
+      end
+
+      it 'passes through array messages without modification' do
+        array_messages = [
+          { 'role' => 'user', 'content' => 'Hello' },
+          { 'role' => 'assistant', 'content' => 'Hi there!' }
+        ]
+        
+        result = described_class.build_body(array_messages, provider, model, temperature)
+
+        expect(result['messages']).to eq(array_messages)
+      end
+    end
+
+    context 'when provider is unsupported' do
+      it 'returns nil for unsupported provider' do
+        result = described_class.build_body(messages, 'unsupported', 'model', temperature)
+
+        expect(result).to be_nil
+      end
+    end
+  end
+
+  describe '.build_headers' do
+    context 'when provider is openai' do
+      let(:provider) { 'openai' }
+
+      it 'returns correct headers for OpenAI' do
+        result = described_class.build_headers(provider, config)
+
+        expect(result).to eq({
+          'Content-Type': 'application/json',
+          'Authorization': "Bearer #{config.openai_api_key}"
+        })
+      end
+
+      it 'includes the API key in Authorization header' do
+        result = described_class.build_headers(provider, config)
+
+        expect(result[:'Authorization']).to eq("Bearer test-openai-key")
+      end
+    end
+
+    context 'when provider is anthropic' do
+      let(:provider) { 'anthropic' }
+
+      it 'returns correct headers for Anthropic' do
+        result = described_class.build_headers(provider, config)
+
+        expect(result).to eq({
+          'x-api-key' => config.anthropic_api_key,
+          'anthropic-version' => '2023-06-01'
+        })
+      end
+
+      it 'includes the API key in x-api-key header' do
+        result = described_class.build_headers(provider, config)
+
+        expect(result['x-api-key']).to eq('test-anthropic-key')
+      end
+
+      it 'includes the correct anthropic-version' do
+        result = described_class.build_headers(provider, config)
+
+        expect(result['anthropic-version']).to eq('2023-06-01')
+      end
+    end
+
+    context 'when provider is unsupported' do
+      it 'returns nil for unsupported provider' do
+        result = described_class.build_headers('unsupported', config)
+
+        expect(result).to be_nil
+      end
+    end
+  end
+
+  describe '.format_messages_for_antropic' do
+    context 'when messages is a string' do
+      it 'converts string to proper message format' do
+        string_message = "Hello world"
+        result = described_class.send(:format_messages_for_antropic, string_message)
+
+        expect(result).to eq([{ 'role' => 'user', 'content' => string_message }])
+      end
+    end
+
+    context 'when messages is already an array' do
+      it 'returns the array unchanged' do
+        array_messages = [
+          { 'role' => 'user', 'content' => 'Question' },
+          { 'role' => 'assistant', 'content' => 'Answer' }
+        ]
+        
+        result = described_class.send(:format_messages_for_antropic, array_messages)
+
+        expect(result).to eq(array_messages)
+      end
+    end
+
+    context 'when messages is empty string' do
+      it 'handles empty string correctly' do
+        result = described_class.send(:format_messages_for_antropic, "")
+
+        expect(result).to eq([{ 'role' => 'user', 'content' => "" }])
+      end
+    end
+
+    context 'when messages is nil' do
+      it 'returns nil unchanged' do
+        result = described_class.send(:format_messages_for_antropic, nil)
+
+        expect(result).to be_nil
+      end
+    end
+  end
+
+  describe 'integration scenarios' do
+    it 'builds complete OpenAI request components' do
+      provider = 'openai'
+      model = 'gpt-4'
+      
+      body = described_class.build_body(messages, provider, model, temperature)
+      headers = described_class.build_headers(provider, config)
+
+      expect(body[:model]).to eq('gpt-4')
+      expect(body[:messages]).to be_an(Array)
+      expect(headers[:'Content-Type']).to eq('application/json')
+      expect(headers[:'Authorization']).to include('Bearer')
+    end
+
+    it 'builds complete Anthropic request components' do
+      provider = 'anthropic'
+      model = 'claude-3-sonnet'
+      
+      body = described_class.build_body(messages, provider, model, temperature)
+      headers = described_class.build_headers(provider, config)
+
+      expect(body['model']).to eq('claude-3-sonnet-20240229')
+      expect(body['messages']).to be_an(Array)
+      expect(body['max_tokens']).to eq(1024)
+      expect(headers['x-api-key']).to eq('test-anthropic-key')
+      expect(headers['anthropic-version']).to eq('2023-06-01')
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/rubyai/provider_spec.rb b/spec/rubyai/provider_spec.rb
new file mode 100644
index 0000000..69d3321
--- /dev/null
+++ b/spec/rubyai/provider_spec.rb
@@ -0,0 +1,16 @@
+require 'webmock/rspec'
+require_relative '../../lib/rubyai/providers/openai.rb'
+require_relative '../../lib/rubyai/providers/anthropic.rb'
+require_relative '../../lib/rubyai/provider.rb'
+
+RSpec.describe RubyAI::Provider do 
+  describe '[]' do
+    it 'should return the OpenAI provider when "openai" is passed' do
+      expect(RubyAI::Provider['openai']).to eq(RubyAI::Providers::OpenAI)
+    end
+
+    it 'should return the Anthropic provider when "anthropic" is passed' do
+      expect(RubyAI::Provider['anthropic']).to eq(RubyAI::Providers::Anthropic)
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/rubyai/providers/anthropic_spec.rb b/spec/rubyai/providers/anthropic_spec.rb
new file mode 100644
index 0000000..ccc6792
--- /dev/null
+++ b/spec/rubyai/providers/anthropic_spec.rb
@@ -0,0 +1,15 @@
+require_relative '../../../lib/rubyai/providers/anthropic'
+
+RSpec.describe RubyAI::Providers::Anthropic do
+  describe '.models' do 
+    it 'should return a list of models' do 
+      expect(described_class.models).to eq( "claude-2" => "claude-2",
+        "claude-instant-100k" => "claude-instant-100k",
+        "claude-1" => "claude-1",
+        "claude-1.3" => "claude-1.3",
+        "claude-1.3-sonnet" => "claude-1.3-sonnet",
+        "claude-1.3-sonnet-100k" => "claude-1.3-sonnet-100k"
+      )
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/rubyai/providers/openai_spec.rb b/spec/rubyai/providers/openai_spec.rb
new file mode 100644
index 0000000..37b1f7d
--- /dev/null
+++ b/spec/rubyai/providers/openai_spec.rb
@@ -0,0 +1,16 @@
+require_relative '../../../lib/rubyai/providers/openai'
+
+RSpec.describe RubyAI::Providers::OpenAI do
+    describe '.models' do 
+    it 'should return a list of models' do 
+      expect(described_class.models).to eq("gpt-3.5-turbo" => "gpt-3.5-turbo",
+        "gpt-4" => "gpt-4",
+        "gpt-4-32k" => "gpt-4-32k",
+        "gpt-4-turbo" => "gpt-4-turbo",
+        "gpt-4o-mini" => "gpt-4o-mini",
+        "o1-mini" => "o1-mini",
+        "o1-preview" => "o1-preview",
+        "text-davinci-003" => "text-davinci-003")
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/rubyai/rubyai_spec.rb b/spec/rubyai/rubyai_spec.rb
new file mode 100644
index 0000000..bdcd471
--- /dev/null
+++ b/spec/rubyai/rubyai_spec.rb
@@ -0,0 +1,52 @@
+require_relative '../../lib/rubyai'
+
+RSpec.describe RubyAI do 
+
+  describe '.models' do 
+    it 'should return available models' do 
+      expect(RubyAI.models).to eq(RubyAI::Configuration::MODELS)
+    end
+  end
+
+  describe '.chat' do 
+    let(:api_key) { 'your_api_key' }
+    let(:messages) { 'Hello, how are you?' }
+    let(:temperature) { 0.7 }
+    let(:model) { 'gpt-3.5-turbo' }
+    let(:provider) { 'openai' }
+    let(:client) { described_class.chat(api_key: api_key, messages: messages, temperature: temperature, provider: provider, model: model) }
+
+
+    let(:response_body) { { 'completion' => 'This is a response from the model.' } }
+    let(:status) { 200 }
+
+    before do
+      stub_request(:post, RubyAI::Configuration::BASE_URL)
+        .to_return(status: status, body: response_body.to_json, headers: { 'Content-Type' => 'application/json' })
+    end
+
+    it 'returns parsed JSON response when passing through client directly' do
+      expect(described_class.chat).to eq(response_body)
+    end
+  end
+
+  describe '.configure' do
+    let(:configuration) {RubyAI.config}
+
+    it 'allows configuration of the client' do
+      described_class.configure do |config|
+        config.api_key = 'your_api_key'
+        config.messages = 'Hello, how are you?'
+        config.temperature = 0.7
+        config.provider = 'openai'
+        config.model = 'gpt-3.5-turbo'
+      end
+
+      expect(configuration.api_key).to eq('your_api_key')
+      expect(configuration.messages).to eq('Hello, how are you?')  
+      expect(configuration.temperature).to eq(0.7)
+      expect(configuration.provider).to eq('openai')
+      expect(configuration.model).to eq('gpt-3.5-turbo')
+    end
+  end
+end
\ No newline at end of file